Fe-7%Mn 합금의 오스테나이트 안정성에 미치는 밀링 시간과 공정제어제 첨가 효과

오승진,손인진,이석재,Oh, Seung-Jin,Shon, In-Jin,Lee, Seok-Jae 한국분말야금학회 2018 한국분말재료학회지 (KPMI) Vol.25 No.2

In the present study, we investigate the effects of milling time and the addition of a process control agent (PCA) on the austenite stability of a nanocrystalline Fe-7%Mn alloy by XRD analysis and micrograph observation. Nanocrystalline Fe-7%Mn alloys samples are successfully fabricated by spark plasma sintering. The crystallite size of ball-milled powder and the volume fraction of austenite in the sintered sample are calculated using XRD analysis. Changes in the shape and structure of alloyed powder according to milling conditions are observed through FE-SEM. It is found that the crystallite size is reduced with increasing milling time and amount of PCA addition due to the variation in the balance between the cold-welding and fracturing processes. As a result, the austenite stability increased, resulting in an exceptionally high volume fraction of austenite retained at room temperature.

유기 나노 보강층을 활용한 유연 디스플레이용 절연막의 기계적 물성 평가

오승진,마부수,양찬희,송명,김택수,Oh, Seung Jin,Ma, Boo Soo,Yang, Chanhee,Song, Myoung,Kim, Taek-Soo 한국마이크로전자및패키징학회 2021 마이크로전자 및 패키징학회지 Vol.28 No.3

최근 유연 디스플레이에 관한 대중의 관심이 증대됨에 따라 롤러블(rollable), 폴더블(foldable) 디스플레이와 같은 우수한 폼 팩터(form factor)를 지닌 차세대 유연(flexible) 디스플레이가 주목받고 있다. 유연 디스플레이의 기계적 신뢰성 확보 측면에서, 내부 절연막으로 활용되는 실리콘 질화물(SiN_x) 박막은 구동 중 발생하는 응력에 매우 취약하므로 기계적 물성을 정확히 파악하여 파손을 예측하고 패널의 전기적 단락을 방지하는 것이 중요하다. 본 논문에서는, ~130 nm, ~320 nm 두께의 SiN_x 박막 박막 상부에 ~190 nm 두께의 유기 나노 보강층(PMMA, PS, P3HT)을 코팅하여 이중층 구조로 인장함으로써 매우 취성한 SiN_x 박막의 탄성 계수와 인장 강도 및 연신율을 측정하는 데 성공하였다. 챔버 압력 및 증착 파워를 조절한 공정 조건(A: 1250 mTorr, 450 W/B: 1000 mTorr, 600 W/C: 750 mTorr, 700 W)을 통해 제작된 ~130 nm SiN_x 의 탄성계수는 A: 76.6±3.5, B: 85.8±4.6, C: 117.4±6.5 GPa로, ~320 nm SiN_x는 A: 100.1±12.9, B: 117.9±9.7, C: 159.6 GPa로 측정되었다. 결과적으로, 동일 공정 조건 하에서 SiN_x 박막의 두께가 증가할수록 탄성 계수가 증가하는 경향을 확인하였으며, 유기 나노 보강층을 활용한 인장 시험법은 파손되기 쉬운 취성 박막의 기계적 물성을 높은 정밀도로 측정하는 데 효과적이었다. 본 연구에서 개발된 방법은, 취약한 디스플레이용 박막의 정량적인 기계적 물성 파악을 가능케하여 강건한 롤러블, 폴더블 디스플레이의 설계에 이바지할 수 있을 것으로 기대한다. Recently, rollable and foldable displays are attracting great attention in the flexible display market due to their excellent form factor. To predict and prevent the mechanical failure of the display panels, it is essential to accurately understand the mechanical properties of brittle SiN_x thin films, which have been used as an insulating film in flexible displays. In this study, tensile properties of the ~130 nm- and ~320 nm-thick SiN_x thin films were successfully measured by coating a ~190 nm-thick organic nano-support-layer (PMMA, PS, P3HT) on the fragile SiN_x thin films and stretching the films as a bilayer state. Young's modulus values of the ~130 nm and ~320 nm SiN_x thin films fabricated through the controlled chamber pressure and deposition power (A: 1250 mTorr, 450 W/B: 1000 mTorr, 600 W/C: 750 mTorr, 700 W) were calculated as A: 76.6±3.5, B: 85.8±4.6, C: 117.4±6.5 GPa and A: 100.1±12.9, B: 117.9±9.7, C: 159.6 GPa, respectively. As a result, Young's modulus of ~320 nm SiN_x thin films fabricated through the same deposition condition increased compared to the ~130 nm SiN_x thin films. The tensile testing method using the organic nano-support-layer was effective in the precise measurement of the mechanical properties of the brittle thin films. The method developed in this study can contribute to the robust design of the rollable and foldable displays by enabling quantitative measurement of mechanical properties of fragile thin films for flexible displays.

플렉서블 디스플레이용 박막 소재 물성 평가

오승진,마부수,김형준,양찬희,김택수,Oh, Seung Jin,Ma, Boo Soo,Kim, Hyeong Jun,Yang, Chanhee,Kim, Taek-Soo 한국마이크로전자및패키징학회 2020 마이크로전자 및 패키징학회지 Vol.27 No.3

차세대 디스플레이 시장을 선도하기 위해서는 롤러블(rollable), 폴더블(foldable) 디스플레이와 같은 플렉서블(flexible) OLED 디스플레이의 상용화 및 양산화가 필수적이나, 실제 공정 및 굽힘 과정에서 발생하는 극심한 박막 내부 응력 변화로 인한 기계적 파손 문제가 심각한 상황이다. 따라서, 플렉서블 디스플레이 구조에 사용되는 박막 재료의 기계적 물성을 파악하는 것은 제품의 강건한 설계 및 구조 최적화에 필수적이다. 본 논문에서는 물 표면 플랫폼을 이용한 나노 박막 인장 시험법을 적용하여 플렉서블 디스플레이 패널에 적용되는 금속 및 세라믹 박막 소재들의 인장 물성을 정량적으로 측정하였다. 스퍼터링(Sputtering)으로 증착된 Mo, MoTi 나노 박막과, 플라즈마 강화 화학 기상 증착법(Plasma Enhanced Chemical Vapor Deposition, PECVD)으로 증착된 SiN_x 나노 박막의 탄성 계수와 인장 강도 및 연신율을 측정하는 데 성공하였다. 결과적으로 박막의 증착 조건 및 두께에 따라 기계적 물성이 크게 변화할 수 있음을 확인하였으며, 측정된 인장 물성은 기계적으로 강건한 롤러블, 폴더블 디스플레이의 설계를 위한 응력 해석 모델링 데이터로 활용될 수 있을 것으로 기대한다. Commercialization of flexible OLED displays, such as rollable and foldable displays, has attracted tremendous interest in next-generation display markets. However, during bending deformation, cracking and delamination of thin films in the flexible display panels are the critical bottleneck for the commercialization. Therefore, measuring mechanical properties of the fragile thin films in the flexible display panels is essential to prevent mechanical failures of the devices. In this study, tensile properties of the metal and ceramic nano-thin films were quantitatively measured by using a direct tensile testing method on the water surface. Elastic modulus, tensile strength, and elongation of the sputtered Mo, MoTi thin films, and PECVD deposited SiN_x thin films were successfully measured. As a result, the tensile properties were varied depending on the deposition conditions and the film thickness. The measured tensile property values can be applied to stress analysis modeling for mechanically robust flexible displays.

단측에 발생한 사구체낭성신질환 1례

오승진,육진원,김지홍,정현주,김명준,김병길,Oh Seung-Jin,Yook Jin-Won,Kim Ji-Hong,Chung Hyun-Ju,Kim Myung-Joon,Kim Pyung-Kil 대한소아신장학회 1999 Childhood kidney diseases Vol.3 No.2

Glomerulocystic kidney disease(GCKD) is a rare form of renal cystic disease defined histopathologically by containing dilated Bowman's space with variable atrophy of glomerular tufts, which may occur as sporadically or as familial cases and can be presented as a major component of heritable syndromes. It has not been recognized in Korean children but only one report of adult case has been reported having GCKD. We experienced a case of GCKD in a 10-year-10-month-old boy, who was admitted for hypertension. Abdominal ultrasonography and computed tomography revealed clustered numerous small cysts in left kidney and renal biopsy findings was consistent with the GCKD showing cystic dilatation of Bowman's space with intact glomerular structure.

직사각형 해양구조물의 자유낙하 슬래밍 충격압력 및 유동특성에 관한 실험적 연구

오승진,김옥석,이경우,조대환,Oh, Seung-Jin,Gim, Ok-Sok,Lee, Gyoung-Woo,Cho, Dae-Wan 해양환경안전학회 2012 해양환경안전학회지 Vol.18 No.4

본 연구에서는 자유낙하하는 직사각형 해양구조물($800{\times}250{\times}50mm^3$)의 슬래밍 충격압력 및 유동특성을 알아보고자 실험을 수행하였다. 유동장의 계측은 2-프레임 그레이레벨 상호상관 PIV기법을 이용하였으며, 자유낙하하는 모델의 충격압력은 압력계측장비(Dewatron)를 이용하였다. 모델과 자유수면간 이루는 각은 $10^{\circ}$와 $20^{\circ}$를 적용하였다. 속도장은 접수보다 이수에서 빠른 유동특성을 나타냈다. 모델 하부에서 충격압력이 가장 높은 지점인 P2 지점에서 $10^{\circ}$보다 경사각이 큰 $20^{\circ}$에서 약 6 % 상승하였다. This paper presents an experimental investigation to figure out slamming impact pressure and flow characteristics of a rectangular Marine structure($800{\times}250{\times}50mm^3$) in free fall. The flow field has been obtained by 2-frame grey level cross correlation PIV(Particle Image Velocimetry) method, the impact pressure of the free fall model by a pressure acquisition system(Dewatron). The angles between a model and the free surface are adapted $10^{\circ}$ and $20^{\circ}$ respectively. Velocity field of water exit has higher better than water entry. The highest point, P2 of impact pressure under the bottom of the model has been appeared about 6 % higher values at 20 degrees than 10 degrees.

나노결정 FeMnNiC합금의 오스테나이트 안정성

오승진,전준협,손인진,이석재,Oh, Seung-Jin,Jeon, Junhyub,Shon, In-Jin,Lee, Seok-Jae 한국분말야금학회 2019 한국분말재료학회지 (KPMI) Vol.26 No.5

In the present study, we have investigated the effect of sintering process conditions on the stability of the austenite phase in the nanocrystalline Fe-5wt.%Mn-0.2wt.%C alloy. The stability and volume fraction of the austenite phase are the key factors that determine the mechanical properties of FeMnC alloys, because strain-induced austenite-martensite transformation occurs under the application of an external stress at room temperature. Nanocrystalline Fe-5wt.%Mn-0.2wt.%C samples are fabricated using the spark plasma sintering method. The stability of the austenite phase in the sintered samples is evaluated by X-ray diffraction analysis and hardness test. The volume fraction of austenite at room temperature increases as the sample is held for 10 min at the sintering temperature, because of carbon diffusion in austenite. Moreover, water quenching effectively prevents the formation of cementite during cooling, resulting in a higher volume fraction of austenite. Furthermore, it is found that the hardness is influenced by both the austenite carbon content and volume fraction.

슬래밍에 의한 쐐기형 구조물 주위의 유동특성에 관한 실험적 연구

오승진,조대환,Oh, Seung-Jin,Cho, Dae-Hwan 해양환경안전학회 2013 海洋環境安全學會誌 Vol.19 No.2

This paper presents are experimental investigation to figure out slamming impact pressure and flow characteristics of a wedge type structure in free fall. The flow field has been obtained by 2-frame grey level cross correlation PIV(Particle Image Velocimetry) method, the impact presure of free fall structure by a pressure acquisition system apply to Dewetron system. The angles between a model and the free surface are adapted $15^{\circ}$, $25^{\circ}$, $35^{\circ}$ and $45^{\circ}$ respectively. Velocity field of water exit has higher better than water entry. The impact pressure under the bottom of the model ha been appeared higher values at 15 degrees than 45 degrees, and also at P1. 본 연구에서는 자유낙하 하는 쐐기형 구조물의 슬래밍 충격압력 및 유동특성을 알아보고자 실험을 수행하였다. 유동장의 계측은 2-프레임 그레이레벨 상호상관 PIV 기법을 이용하였으며, 자유낙하 하는 구조물의 충격압력은 압력 계측장비인 Dewetron System을 이용하였다. 모델과 자유수면간 이루는 각도는 $15^{\circ}$, $25^{\circ}$, $35^{\circ}$ 및 $45^{\circ}$를 적용하였으며 중량과 자유낙하의 높이에 대해서 다양성을 주어 실험하였다. 속도장은 접수보다 이수에서 빠른 유동특성을 나타냈으며, 접수에서 보다 이수에서 시간이 더 소요됨을 보였으며, 모델 하부에서의 충격압력은 모델의 45도에서 보다, 입수각이 작은 15도와 P1 지점에서 높게 나타났다.

외교문제에 대한 최근 판례의 분석

오승진(Seung Jin Oh) 서울국제법연구원 2013 서울국제법연구 Vol.20 No.2

Numerical study on a multi-stage counter-flow indirect evaporative cooler

Seung Jin Oh(오승진),Yong Woo Yang(양용우),Yoon Jung Ko(고윤정) 대한설비공학회 2021 대한설비공학회 학술발표대회논문집 Vol.2021 No.6

This study presents the numerical modeling and the simulation of a counter-flow indirect evaporative cooler (IEC) that is thermodynamically multi-staged in order to maximize its performance. The proposed indirect evaporative cooler is basically a stack of identical IEC modules. The working principle is such that a certain portion of the dry air at the outlet of the first module is purged into the wet channel of the next module that is located underneath and the remaining is transferred to the dry channel. A series of simulation was conducted to investigate the performance of the multi-stage IEC The developed model was validated against experimental data within 2% discrepancy. Key results revealed that the proposed multi-stage counter-flow IEC produced higher cooling capacity (around 20% higher), as well as higher dew-point effectiveness under the same operating conditions. A parametric study was also made in order to find optimal operating conditions as well as optimal dimension. The results revealed that lower product air temperature and higher dew-point effectiveness were achieved with longer channel length and larger purge ratio. However, the maximum cooling capacity approached its maximum with longer channel length and 35% purge ratio.

국제법상 국가면제 -국제인권법의 관점에서-

오승진 ( Seung Jin Oh ) 안암법학회 2009 안암 법학 Vol.0 No.28

It is widely accepted that a foreign state enjoys some jurisdictional immunity in the domestic courts of another state. The doctrine is based on the equality of sovereignty, and practical reasons to avoid unnecessary conflicts among countries. State immunity developed from absolute immunity to restrictive immunity. The theory of restrictive immunity divides state acts into sovereign, public acts and private, commercial acts, and the privilege of immunity is denied to the latter. Domestic legislation such as the U.S. and the United Kingdom, and the U.N. Convention on Jurisdictional Immunities of States and Their Property follow restrictive immunity but still grant state immunity to human rights violations by states. The development of international human rights after World War II, however, has weakened the theory of absolute sovereignty, and promotion and protection of human rights became international concern. Accordingly, gross human rights violations cannot be justified by sovereignty. Universal jurisdiction, which allows any state to prosecute individuals responsible for violating international crimes, has been increasingly accepted. Allowing torts claims against a state responsible for gross human rights violations such as torture contributes to preventing similar human rights violations in the future and enforcing international norms in domestic courts. Considering that diplomatic protection and other mechanism to protect individuals are not sufficiently efficient, remedy by domestic courts could be one of the alternatives. Morever, prohibition of torture is considered as jus cogens. Therefore, denying civil jurisdiction based on state immunity, which is lower in status than jus cogens, cannot be justified. State immunity, which has been a serious obstacle to civil remedy in case of human rights violations, should be reconsidered.