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Printed Origami Structures

Bok Yeop Ahn, Daisuke Shoji, Christopher J. Hansen, Eunji Hong, David C. Dunand, Jennifer A. Lewis
2010 Advanced Materials  
Figure 1 . a) Optical image of direct ink writing of a concentrated TiH 2 ink. b) SEM images of printed square lattice and wavy patterns. c) Shear elastic modulus (G 0 ) of TiH 2 inks as a function of solids loading. d) Storage modulus (E 0 ) of printed filaments of varying 2-butoxyethanol:DBP ratio as a function of drying time, where the shaded region denotes optimal E 0 values for origami-based assembly.
doi:10.1002/adma.200904232 pmid:20397151 fatcat:qrtanibgjjbx3p5jz227yvlvj4

Cyber Attack and Defense Emulation Agents

Jeong Do Yoo, Eunji Park, Gyungmin Lee, Myung Kil Ahn, Donghwa Kim, Seongyun Seo, Huy Kang Kim
2020 Applied Sciences  
As the scale of the system and network grows, IT infrastructure becomes more complex and hard to be managed. Many organizations have a serious problem to manage their system and network security. In addition, vulnerabilities of hardware and software are increasing in number rapidly. In such a complex IT environment, security administrators need more practical and automated threat assessment methods to reduce their manual tasks. Adversary emulation based automated assessment is one of the
more » ... ns to solve the aforementioned problems because it helps to discover the attack paths and vulnerabilities to be exploited. However, it is still inefficient to perform the adversary emulation because adversary emulation requires well-designed attack scenarios created by security experts. Besides, a manual-based penetration test cannot be frequently performed. To overcome this limitation, we propose an adversary emulation framework composed of the red team and blue team agent. The red team agent carries out automated attacks based on the automatically generated scenarios by the proposed framework. The blue team agent deploys defense measures to react to the red team agent's attack patterns. To test our framework, we test multiple attack scenarios on remote servers that have various vulnerable software. In the experiment, we show the red team agent can gain an administrator's privilege from the remote side when the blue team agent's intervention is not enabled. The blue team agent can successfully block the red team's incoming attack when enabled. As a result, we show our proposed framework is beneficial to support routine threat assessment from the adversary's perspective. It will be useful for security administrators to make security defense strategy based on the test results.
doi:10.3390/app10062140 fatcat:obfpdkifijfn5etimwr7uw4r6e

Microstructure and Mechanical Properties of Reticulated Titanium Scrolls

Eunji Hong, Bok Y. Ahn, Daisuke Shoji, Jennifer A. Lewis, David C. Dunand
2011 Advanced Engineering Materials  
Titanium and its alloys find widespread use in skeletal implants and biomedical devices (e.g., stents and orthodontic applications) owing to their excellent corrosion resistance, bio-compatibility, static and fatigue strength, and lack of magnetism (an important property for magnetic imaging). [1] Microporous titanium provides two additional advantages for implant applications: first, it reduces the stiffness of the material, thus reducing stress shielding, [2, 3] and, second, it improves
more » ... t anchorage by allowing bone ingrowth. [4] [5] [6] To date, powder metallurgy approaches have been widely used to create porous Ti structures, through partial sintering, [7] [8] [9] inclusion of pore formers, [10] [11] [12] [13] expansion of pores pressurized with argon or hydrogen gas, [14, 15] or replication of cellular polymers. [16, 17] Embrittlement often arises during processing due to the strong chemical affinity of titanium at elevated temperature with atmospheric oxygen, carbon, and nitrogen. Alternate efforts have focused on producing microarchitectured titanium, composed of lattice or truss structures with struts arranged periodically in space. These structures exhibit an outstanding combination of low density, high strength and stiffness, and good damage tolerance. [18] To date, production methods for microarchitectured titanium have focused on replication precision casting, [19, 20] sintering of stacked wire arrays, [21] as well as selective electron beam, [22] [23] [24] or laser [25] sintering of Ti powders. Recently, we introduced a new method for creating 3D microarchitectured Ti structures that combines: [26] (i) direct ink writing (DIW) of planar lattices composed of two layers of orthogonally oriented, patterned TiH 2 filament arrays, followed by (ii) rolling of these pliable lattices into scrolls, or folding into complex three-dimensional shapes, and finally (iii) heat-treating to reduce the hydride to metallic titanium. This new method is characterized by its simplicity, high shape versatility, and ability to control local geometry, as well as scalability to larger structures. [26] Here, we use this novel COMMUNICATION [*] Prof.
doi:10.1002/adem.201100082 fatcat:sggddwrb6bhjnp7grnysqyxkfq

Simultaneous Laparoscopic-Assisted Colorectal Resection and Nephrectomy

Seunghun Lee, Seung-Hyun Lee, Taeksang Kim, Sunguhn Baek, Byungkwon Ahn, Jooweon Chung, Eunji Kim
2017 Journal of Minimally Invasive Surgery  
Simultaneous laparoscopic surgery for colorectal cancer and coexisting abdominal disease is shown to be feasible. However, simultaneous laparoscopic colorectal resection and nephrectomy is rarely documented, and its feasibility is unknown. We report two cases of simultaneous colorectal resection for colorectal cancer and nephrectomy. In the first case, a 71-year-old female underwent laparoscopic right hemicolectomy for an ascending colon cancer and left nephrectomy for a left non-functioning
more » ... ney. The second patient was a 77-year-old male with descending colon cancer and left renal cell carcinoma who underwent laparoscopic left hemicolectomy and left nephrectomy. The body mass indexes were 21.73 and 26.78 kg/m 2 , respectively, and operation time was 275 and 395 minutes. Blood loss was 300 and 250 cc, and the postoperative hospital stay was 8 and 10 days. In both cases, there was no postoperative morbidity or mortality. Simultaneous laparoscopic resection for colorectal cancer and nephrectomy is a feasible and safe procedure.
doi:10.7602/jmis.2017.20.1.46 fatcat:oqcv6yzrczfo5iuelkctclbnsa

Design and implementation of user-level remote memory extension library

Shinyoung Ahn, Gyuil Cha, Youngho Kim, Eunji Lim
2015 2015 17th International Conference on Advanced Communication Technology (ICACT)  
The increase of memory capacity has not kept up with the continuous increase of large memory applications. Therefore, approaches to utilize remote memory like a local memory has been considered as a cost effective way to run large memory application in the cluster environment where computing nodes are connected via high speed network. For the users of HPC cluster to run large memory application without administrator's support, we suggest a user-level remote memory extension method. We designed
more » ... nd implemented a remote memory library model which extends the virtual address space of the large memory application process to remote memory. It includes userlevel API and page fault handling mechanism, temporal page pool management and remote page prefetching algorithm. We also developed a performance test program to show if the userlevel remote memory extension library works well. From the experimental test, we found that user-level remote memory extension library works well for applications with sequential access pattern.
doi:10.1109/icact.2015.7224893 fatcat:e3dqro4y4nfktor3sujt6cwbii

Association between Metabolic Components and Subclinical Atherosclerosis in Korean Adults

In Cheol Hwang, Sang-Yeon Suh, Ah-Ram Seo, Hong Yup Ahn, Eunji Yim
2012 Korean Journal of Family Medicine  
Many studies have attempted to develop relatively simple and easy noninvasive measurements of atherosclerosis (NIMA), and each NIMA assesses different atherosclerotic properties. We, therefore, investigated the association between metabolic syndrome (MetS) components and different NIMAs. Methods: This study included 1,132 Korean subjects over 20 years of age who had visited a Health Promotion Center in Korea. Carotid injury (increased carotid intima-media thickness or plaques) was evaluated by
more » ... ltrasonography and arterial stiffness by brachial-ankle pulse wave velocity. The MetS components were assessed according to the Asian criteria of the American Heart Association/National Heart, Lung, and Blood Institute. Results: Both arterial stiffness and carotid injury gradually deteriorated with increase in the number of MetS components. Arterial stiffness and carotid injury were associated with different MetS components, each of which had varying impact. After adjustment for all possible confounders such as age, sex, and lifestyle, elevated blood pressure (BP) was found to have the strongest association with arterial stiffness, whereas central obesity, impaired fasting plasma glucose, and elevated BP had comparable connection with carotid atherosclerosis. Conclusion: Individual MetS components were related with subclinical atherosclerosis in different ways. Elevated BP showed the strongest association with arterial stiffness, while central obesity, impaired fasting plasma glucose, and elevated BP showed good correlation with carotid atherosclerosis.
doi:10.4082/kjfm.2012.33.4.229 pmid:22916325 pmcid:PMC3418342 fatcat:othwdah44jfurb2lezesvqqmfe

SoftMemoryBox II: A Scalable, Shared Memory Buffer Framework for Accelerating Distributed Training of Large-scale Deep Neural Networks

Shinyoung Ahn, Eunji Lim
2020 IEEE Access  
Ahn et al.: SMB2: A Scalable, Shared Memory Buffer Framework for Accelerating Distributed Training of Large-scale DNNsFIGURE 3.  ... 
doi:10.1109/access.2020.3038112 fatcat:mduv22whdjakbjxpc7orcfgzc4

Effects of Repeated Ovarian Stimulation on Ovarian Function and Aging in Mice

Jihye Whang, Cheyoung Ahn, Soohyun Kim, Eunji Seok, Yunjeong Yang, Goeun Han, Haeun Jo, Hyunwon Yang
2021 Development & Reproduction  
| 217 J Whang, C Ahn, S Kim, E Seok, Y Yang, G Han, H Jo, H Yang | https://www.ksdb.org https://doi.org/10.12717/DR.2021.25.4.213 https://www.ksdb.org | 219 J Whang, C Ahn, S Kim, E Seok, Y  ...  Yang, G Han, H Jo, H Yang https://www.ksdb.org | 221 J Whang, C Ahn, S Kim, E Seok, Y Yang, G Han, H Jo, H Yang https://www.ksdb.org | 223 J Whang, C Ahn, S Kim, E Seok, Y Yang, G Han, H Jo,  ... 
doi:10.12717/dr.2021.25.4.213 pmid:35141447 pmcid:PMC8807135 fatcat:z2zff4yaujgmrgj2o5uudpvoqy

An Analysis of Infographics Used in Korean Optical Newspaper
안경 신문에 사용된 인포그래픽 분석

Jisun Jun, Semi Kim, Jihye Ahn, Jin A Park, EunJi Oh, Moonsung Choi
2017 Journal of Korean Ophthalmic Optics Society  
doi:10.14479/jkoos.2017.22.4.341 fatcat:qttp3eamkbezlddprtvcwex6oq

Integrative gene network construction for predicting a set of complementary prostate cancer genes

Jaegyoon Ahn, Youngmi Yoon, Chihyun Park, Eunji Shin, Sanghyun Park
2011 Computer applications in the biosciences : CABIOS  
Beside the subnetworks discussed above, we provide subnetwork files in SIF format for visualization in Cytoscape at http://embio.yonsei.ac.kr/∼Ahn/tc.php.  ...  DISCUSSIONS To analyze the cancer-specific gene network, we firstly clustered it into modules using network clustering algorithm (Ahn et al., 2010) , which hierarchically detect the modules in the network  ... 
doi:10.1093/bioinformatics/btr283 pmid:21551151 fatcat:mxqlnuioa5astmaku2kxrea3ei

Numerical Simulation for Transonic Wing-Body Configuration using CFD
CFD를 이용한 천음속 날개-동체 형상 해석

Younghwa Kim, Eunji Kang, Hyokeun Ahn
2017 Journal of the Korean Society for Aeronautical & Space Sciences  
The flowfield around transonic wing-body configuration was simulated using in-house CFD code and compared with the experimental data to understand the influence of several features of CFD(Computational Fluid Dynamics) ; grid dependency, turbulence models, spatial discretization, and viscosity. The wing-body configuration consists of a simple planform RAE Wing 'A' with an RAE 101 airfoil section and an axisymmetric body. The in-house CFD code is a compressible Euler/Navier-Stokes solver based on
more » ... unstructured grid. For the turbulence model, the k-ω model, the Spalart-Allmaras model, and the k-ω SST model were applied. For the spatial discretization method, the central differencing scheme with Jameson's artificial viscosity and Roe's upwind differencing scheme were applied. The results calculated were generally in good agreement with experimental data. However, it was shown that the pressure distribution and shock-wave position were slightly affected by the turbulence models and the spatial discretization methods. It was known that the turbulent viscous effect should be considered in order to predict the accurate shock wave position. 초 록 본 연구에서는 전산유체역학의 특징에 대한 이해를 위해 천음속 날개-동체 주위의 유동장을 In-house 전산유체 코드로 해석하여 시험 결과와 비교하였다. 날개는 RAE 101 익형 단면을 가 진 RAE Wing 'A'이며 동체는 축대칭 형상이다. In-house 코드는 비정렬 격자 기반의 압축성 Euler/Navier-Stokes 해석 코드이다. 격자에 대한 의존도, 난류 모형, 공간차분 기법, 점성/비점 성의 영향을 시험 결과와 비교하여 살펴보았다. 난류 모형은 k-ω 모형, Spalart-Allmaras 모형, k--ω SST을 적용하였고, 공간차분 기법은 Jameson의 인공 점성를 도입한 중앙 차분 기법과 Roe의 풍상 차분 기법을 적용하였다. 대체적으로 시험 결과를 잘 예측하였으나, 압력분포 및 충격파의 위치가 난류 모형 및 공간 차분 기법에 따라 조금씩 다르게 예측되었으며, 정확한 충 격파 위치를 예측하기 위해서는 난류 점성 효과가 고려되어야 함을 알 수 있다.
doi:10.5139/jksas.2017.45.3.233 fatcat:f77kq3cjwrbbzczhhbl27ndzoa

Body donation trends in Yonsei University: a statistical analysis of donor records

Hyun Jin Park, Haeryun Ahn, Eunji Ki, Je Seong Lee, Yiseul Choi, Kyung-Seok Hu, Yong-Min Chun, Hee-Jin Kim
2021 Anatomy & Cell Biology  
Body donation trends in Korea have changed significantly over the last 3 decades. Establishing a body donation system will promote donations to universities for academic purposes. Yonsei University College of Medicine started its own body donation system in 1992, including documenting donors' records. However, there has been no reported attempt to analyze the trend of these records, which could provide noteworthy information that can be interpreted for medical advances. This study performed a
more » ... atistical analysis of the donors' records between 1992 and 2019 to analyze the sociological and anthropological changes. Donor personal information such as sex, age, religion, and place and cause of death were extracted from the Yonsei University College of Medicine database. Our statistical analysis revealed significant correlations between donors' records and the changes in the number of geriatric hospitals, religious beliefs, number of donations, and donor age.
doi:10.5115/acb.20.261 pmid:33424016 pmcid:PMC8017449 fatcat:6cp3d4pmbnfenfa73d5fslckhe

Postoperative Clinical Outcomes of Thoracoscopic Surgery under Local Anesthesia in Patients with Primary Spontaneous Pneumothorax

Eunji Kim, Chi-Seung Lee, Jeong Su Cho, Hoseok I, Yeong Dae Kim, Eunsoo Kim, Hyo Yeong Ahn
2021 Applied Sciences  
(1) Background: since the technologies of anesthesia and surgery were advanced, video-assisted thoracic surgery (VATS) under local anesthesia (LA) has been widely carried out and is considered a robust surgical technique to prevent the recurrence of pneumothorax in patients with recurrent primary spontaneous pneumothorax (PSP). In this study, postoperative clinical outcomes were compared to evaluate the feasibility and efficacy of VATS under LA compared with general anesthesia (GA) in patients
more » ... ith PSP. (2) Methods: 255 patients underwent wedge resection underwent VATS for PSP in our hospital from January 2014 to June 2019. Of them, 30 patients underwent the operation under LA and the others underwent the operation under GA. Except for the anesthesia method, the same surgical technique was adopted for all patients. All medical records were retrospectively reviewed. (3) Results: the total operation time and total hospital days were relatively shorter, post-chest tube drainage was significantly shorter (0.04), and visual analog scale (VAS) scores in the outpatient clinic were significantly lower in the LA group than in the GA group (p = 0.01). The incidence of postoperative recurrence after discharge in the LA group (3.3%) was also lower than in the GA group (18.67%) (p = 0.001). In the LA group, there were no cases of conversion to intubation. (4) Conclusions: our results showed relatively better clinical outcomes in VATS under LA with sedation than under GA in the treatment of PSP. Hence, LA with sedation can be considered as a robust anesthetic technique for VATS and as applicable in the surgical treatment of PSP.
doi:10.3390/app11041468 fatcat:xn4s7aqolraf5nkzo7m4dg7c5e

In vivo longitudinal depth-wise visualization of tumorigenesis by needle-shaped side-view confocal endomicroscopy

Jinhyo Ahn, Eunji Kong, Kibaek Choe, Eunjoo Song, Yoonha Hwang, Howon Seo, Inwon Park, Pilhan Kim
2019 Biomedical Optics Express  
In vivo, longitudinal observation of tumorigenesis in a live mouse model over an extended time period has been actively pursued to obtain a better understanding of the cellular and molecular mechanism in a highly complex tumor microenvironment. However, common intravital imaging approaches based on a conventional laser scanning confocal or a two-photon microscope have been mostly limited to the observation of superficial parts of the solid tumor tissue. In this work, we implemented a small
more » ... ter needle-shaped side-view confocal endomicroscope that can be directly inserted into a solid tumor in a minimally-invasive manner in vivo. By inserting the side-view endomicroscope into the breast tumor from the surface, we achieved in vivo depth-wise cellular-level visualization of microvasculature and fluorescently labeled tumor cells located deeply inside the tumor. In addition, we successfully performed longitudinal depth-wise visualization of a growing breast tumor over three weeks in a live mouse model, which revealed dynamic changes in microvasculature such as a decreasing amount of intratumoral blood vessels over time.
doi:10.1364/boe.10.002719 pmid:31259046 pmcid:PMC6583337 fatcat:7v7fqkgpcbahvnsletw6wwfrre

Current status of quality of care for public hospitals in Korea : Comprehensive comparison with private hospitals

Hey Jin Ko, Eunji Yun, Boryung Ahn, Won Mo Jang, Jin Yong Lee
2021 Public Health Affairs  
Objective: This ecological study aims to perform a comprehensive comparison and evaluation of the quality of care in public and private hospitals according to hospital type.Methods: Thisstudy compared and analyzed the results of the National Quality Assessment Program (NQAP) of Health Insurance Review and Assessment Service (HIRA) and Incentive Scheme for Quality Evaluation of Hospital Services. The NQAP results published on the HIRA website, as of the end of May 2021, and the internal data of
more » ... IRA for the 2020 Incentive Scheme for Quality Evaluation of Hospital Services were used as data collection sources.Results: The NQAP analysisrevealed that the overall average scores were higher for public rather than private hospitals, while the Incentive Scheme for Quality Evaluation of Hospital Services analysis reported that the proportion of higher grades (i.e., grades 1 and 2) was higher in public hospitals. Therefore, it was revealed that public hospital quality levels were notlowerthan that of private hospitals.However, itis necessary to improve the quality levelsin terms ofthe quality distribution.Conclusions: The quality levels of public hospitals are notlowerthan that of private hospitals. However,the high average quality level, we identified certain areas that required improvement in their quality level throughout the distribution. Currently, public hospitals that are particularly located in the lower ranks should strive to achieve the average quality level demonstrated by same level private hospitals, thereby, achieving progressive quality levels and minimizing the between institutions. Thus, furtherresearch should focus on identifying the trends of differencesin quality levels, and they should determine the causes by controlling for the characteristics of medical institutions.
doi:10.29339/pha.21.10 fatcat:dkxzjhmkwzakpa66c64frv5lge
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