P.C. Box Girder 橋梁의 溫度影響分析

손기훈,이성우 국민대학교 1999 北岳論叢 Vol.16 No.-

수소 도핑효과에 의한 ZnO 맴트랜지스터 소자특성

손기훈,강경문,박형호,이홍섭,Son, Ki-Hoon,Kang, Kyung-Mun,Park, Hyung-Ho,Lee, Hong-Sub 한국마이크로전자및패키징학회 2020 마이크로전자 및 패키징학회지 Vol.27 No.1

원자층 증착법(ALD: atomic layer deposition)으로 성장된 ZnO n-type 산화물반도체를 이용하여 three terminal memristor (memtransistor) 소자를 제작하여 습도에 따른 그 특성을 관찰하였다. 40 nm 두께의 ZnO 박막을 이용하여 channel width 70 ㎛, length 5 ㎛, back gate 구조의 memtransistor 소자를 제작하여 습도에 (40%, 50%, 60%, 70%) 따른 gate tunable memristive 특성변화를 관찰하였다. 습도가 높아질수록 electron mobility와 gate controllability가 감소하여 수소도핑효과에 의한 carrier 농도가 증가하는 거동의 output curve가 관찰되었다. 60%, 70%의 습도에서 memristive 거동이 관찰되었으며 습도가 높아질수록 on/off ratio는 증가하는 반면 gate controllability가 감소하였다. 60% 습도에서 가장 우수한 특성의 gate tunable memristive 특성을 얻을 수 있었다. This study demonstrates metal-oxide based memtransistor device and the gate tunable memristive characteristic using atomic layer deposition (ALD) and ZnO n-type oxide semiconductor. We fabricated a memtransistor device having channel width 70 ㎛, channel length 5 ㎛, back gate, using 40 nm thick ZnO thin film, and measured gate-tunable memristive characteristics at each gate voltage (50V, 30V, 10V, 0V, -10V, -30V, -50V) under humidity of 40%, 50%, 60%, and 70% respectively, in order to investigate the relation between a memristive characteristic and hydrogen doping effect on the ZnO memtransistor device. The electron mobility and gate controllability of memtransistor device decreased with an increase of humidity due to increased electron carrier concentration by hydrogen doping effect. The gate-tunable memristive characteristic was observed under humidity of 60% 70%. Resistive switching ratio increased with an increase of humidity while it loses gate controllability. Consequently, we could obtain both gate controllability and the large resistive switching ratio under humidity of 60%.

PTFE 분말 첨가에 따른 우레아 그리스의 윤활 및 유변학 특성 연구

손기훈,이동규,이영석,우재구,하기룡 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.2

In this study, the rheological and tribological properties of urea grease were studied according to the type and amount of polytetrafluoroethylene (PTFE) powders added to the urea grease, which is the most widely used among solid lubricants, to develop an optimal lubrication system. Urea grease was synthesized using 4,4'-methylenebis(phenyl isocyanate)(MDI), oleylamine, and cyclohexylamine, and PTFE powders prepared by dispersion or suspension polymerization process were then added. The basic rheological and tribological properties of the prepared greases were compared. The worked penetration numbers of urea grease decreased with increasing amount of PTFE powders, but both PTFE powders caused no significant changes in heat resistance and copper corrosion resistance. The shear viscosity increased with increasing PTFE powder content, and the dispersion-type PTFE powder was more effective in increasing the viscosity. In the value of the loss coefficient = 1, the shear stress was higher for the grease containing PTFE powders than the non-PTFE added grease, and the dispersion-type PTFE-added grease showed higher viscosity than the suspension-type PTFE-added grease. Finally, urea grease was found to have a low-performance improvement in terms of wear reduction effects by adding PTFE powders, but the load-bearing performance was up to 2.5 times higher for the dispersion-type PTFE and five times higher for the suspension-type PTFE 본 연구에서는 고체윤활제 중 가장 널리 사용되는 폴리테트라플루오로에틸렌(PTFE) 분말의 종류와 투입량에 따른 우레아 그리스의 윤활 및 유변학 특성 변화를 연구하여 최적의 윤활시스템을 구축하고자 하였다. 4,4’-메틸렌 다이페닐 다이아이소사이아네이트(MDI), 올레일아민과 시클로헥실아민을 사용하여 우레아 그리스를 합성하고, 분산법 혹은 현탁법으로 중합된 PTFE 분말을 함량별로 투입하여 그리스를 제조하였다. 제조된 그리스의 기본물성, 유변학적 및 트라이볼로지 특성을 비교하였다. 그 결과, PTFE의 첨가량에 따라 우레아 그리스의 주도값은 감소하지만 변화폭은 분산형 PTFE가 상대적으로 더 큰 것으로 확인되었다. 내열성과 동판부식 영향성에서는 두 가지 PTFE 분말 모두 큰 변화가 없는 것을 확인하였다. PTFE 분말의 함량 증가에 따라 전단점도는 상승하였으며, 분산형 PTFE가 점도 상승에 더 효과가 있음을 확인하였다. 손실계수의 값이 1인 점에서 전단응력은 PTFE 분말이 첨가되지 않은 그리스 보다 첨가된 그리스가 더 높았고, 분산형 PTFE가 현탁형 PTFE보다 더 큰 것을 확인하였다. 두 가지 PTFE 분말 모두 우레아 그리스의 마모 감소 효과에 대한 성능 향상은 낮았지만, 내 하중 성능은 분산형 PTFE는 최대 2.5배, 현탁형 PTFE는 최대 5배의 증대 효과가 있는 것을 확인하였다.

생체리듬과 신경내분비 시스템

손기훈,정수영,김경진 대한내분비학회 2010 Endocrinology and metabolism Vol.25 No.4

Postmortem mRNA Expression Patterns in Left Ventricular Myocardial Tissues and Their Implications for Forensic Diagnosis of Sudden Cardiac Death

손기훈,박성환,김윤미,Ji Yeon Kim,Jin Wook Kim,정수영,김유훈,김현,황적준,서중석 한국분자세포생물학회 2014 Molecules and cells Vol.37 No.3

Sudden cardiac death (SCD), which is primarily caused by lethal heart disorders resulting in structural and arrhythmogenic abnormalities, is one of the prevalent modes of death in most developed countries. Myocardial ischemia, mainly due to coronary artery disease, is the most common type of heart disease leading to SCD. However, postmortem diagnosis of SCD is frequently complicated by obscure histological evidence. Here, we show that certain mRNA species, namely those encoding hemoglobin A1/2 and B (Hba1/2 and Hbb, respectively) as well as pyruvate dehydrogenase kinase 4 (Pdk4), exhibit distinct postmortem expression patterns in the left ventricular free wall of SCD subjects when compared with their expression patterns in the corresponding tissues from control subjects with non-cardiac causes of death. Hba1/2 and Hbb mRNA expression levels were higher in ischemic SCD cases with acute myocardial infarction or ischemic heart disease without recent infarction, and even in cardiac death subjects without apparent pathological signs of heart injuries, than control subjects. By contrast, Pdk4 mRNA was expressed at lower levels in SCD subjects. In conclusion, we found that altered myocardial Hba1/2, Hbb, and Pdk4 mRNA expression patterns can be employed as molecular signatures of fatal cardiac dysfunction to forensically implicate SCD as the primary cause of death.

림프부종에서 연조직염과 관련된 가역적인 뇌량팽대 병변

손기훈,이소영,이원구,이진형,김명국,유봉구 대한신경집중치료학회 2017 대한신경집중치료학회지 Vol.10 No.2

열분해유 기반 윤활기유를 활용한 윤활그리스 제조 및 특성평가

손기훈 한국환경에너지공학회 2023 한국열환경공학회 학술대회지 Vol.2023 No.2

P.C. 상자형 교량의 온도영향분석

손기훈,이성우 대한토목학회 1998 대한토목학회 학술발표회 논문집 Vol.1998 No.1

Circadian molecular clockworks in the skin

손기훈 ( Gi Hoon Son ) 한국피부장벽학회 2023 한국피부장벽학회지 Vol.25 No.2

Circadian rhythms underlie a wide range of biological processes controlling physiology, metabolism and behavior. The circadian timing system in mammals is hierarchically organized with a master pacemaker in the hypothalamus, and orchestrates the overt biological rhythms. Such periodicity is crucial for homeostasis because disruption or misalignment of the intrinsic rhythms is associated with the onset and progression of various human diseases and often directly leads to pathological states. Since mammalian circadian clock genes were identified in the 1990’s, numerous studies have uncovered the molecular basis of the cell-autonomous and self-sustainable rhythms. These rhythms are primarily generated by two interlocking transcription/ translation feedback loops of clock proteins at a cellular level, which then induce circadian expression of sets of genes in a given cell by cooperating with cell type-specific transcriptional machinery. As our understanding of the regulatory mechanisms and their functional outputs has expanded, pharmacological strategies have been developed to modulate the circadian molecular clockworks. Small molecules that directly target the molecular clock or improve the efficacy of the existing therapeutic strategies via the intrinsic clock-dependent mechanisms, may provide novel therapeutic strategies to treat chronic circadian rhythm-related diseases. Notably, it has been well established that structural and/or functional features of skin barrier follow robust diurnal oscillations; these include skin thickness, cell proliferation, DNA repair, barrier permeability and itching. In good agreement with the notion, recent transcriptomic studies clearly demonstrated that skin cells harbor cell-autonomous circadian clockworks and exhibit cyclic expressions of key genes responsible for the skin barrier functions. These findings collectively suggest that circadian molecular clocks in the skin tissues play a pivotal role in maintaining integrity and functional homeostasis of skin barrier. Therefore, it is plausible that pharmacological reinforcement of molecular clockworks could be applicable for certain pathological conditions of skin, which is linked with circadian dysfunctions.

ESO (epoxidized soybean oil)을 활용한 바이오 폴리올 에스터 제조와 친환경 윤활기유 및 그리스 제조

손기훈(Ki-hoon Son),우재구(JaeGu Woo),최원준(Won-Jun Choi),황기섭(Ki-Seob Hwang) 한국트라이볼로지학회 2022 한국트라이볼로지학회 학술대회 Vol.2022 No.4