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Wheel fastener 재사용을 위한 토크에 따른 축력 측정 방법 비교
우상원(Sangwon Woo),김진호(Jinho Kim),김정주(Jungjoo Kim) 한국자동차공학회 2016 한국자동차공학회 부문종합 학술대회 Vol.2016 No.5
In this paper focuses on compare three torque tension measuring methods for Wheel fastener. By comparison with these method, find merits and weakness each method. Torque tension tests are performed to compare these methods and find merit and weakness for each section. Preparation, measuring method, application and result(stable or not). Furthermore, find the appropriate method for wheel fastener reuse test.
우상원(Sangwon Woo),김진호(Jinho Kim),박창언(Changeon Park) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
In this paper focuses on introduce ultrasonic testing method to measuring torque-tension test of Wheel fastener. By contrast with some sensors for measuring tension-compression, Ultrasonic testing method is non-destructive test that is not necessary test sample machining. So, the yield strength and prooflaod of bolts doesn’t become weaken. If we use machined sample, we will get lower yieldstrength and proof load than data from not machined sample. And We can measure the clamp load drop as time passes. Also with ultrasonic testing method we can apply test to real car. Get more stable result than other method. Because We can consider the friction, when we use ultrasonic method.
Choi, Seong-Woo,Won, Jong Woo,Lee, Sangwon,Hong, Jea Keun,Choi, Yoon Suk Elsevier 2018 Materials science & engineering. properties, micro Vol.738 No.-
<P><B>Abstract</B></P> <P>We compared deformation twinning activity and twin structure development of pure Ti at cryogenic temperature and room temperature by conducting unidirectional rolling at 77 K and 293 K. Twinning activity was significantly higher in rolling at 77 K than in rolling at 293 K. This was because lowering the deformation temperature increased the necessity for twinning operation to compensate for reduced accommodation of strain along the <I>c</I>-axis of the crystal structure, caused by inhibition of <<I>c</I>+<I>a</I>> slips. Twin structure was also entirely different between the two rolling temperatures. Compared to the case of rolling at 293 K, rolling at 77 K generated thin and numerous individual twins in the twinned grains, thereby giving rise to the development of a totally different twin structure. The differences in twin structure were caused by the combined effect of significant local stress concentration at grain boundaries and a reduction in stacking fault energy by rolling at 77 K. The twin structure strongly contributed to severe twinning-induced grain refinement that occurs at cryogenic temperature.</P>
Stress Corrosion Cracking of Heat Exchanger Tubes in District Heating System
( Sangwon Cho ),( Seon-hong Kim ),( Woo-cheol Kim ),( Jung-gu Kim ) 한국부식방식학회(구 한국부식학회) 2019 Corrosion Science and Technology Vol.18 No.2
The purpose of this paper is to present failure analysis, of the heat exchanger tube in a district heating system. SS304 stainless steel is used, as material for the heat exchanger tube. The heat exchanger operates in a soft water environment containing a small amount of chloride ions, and regularly repeats operation and standstill period. This causes concentration of chloride ions on the outer surface of the tube, as well as repeat of thermal expansion, and shrinkage of the tube. As a result of microscopic examination, cracks showed transgranular as well as branched propagation, and many pits were present, at the initiation point of each crack. Energy disperstive spectroscopy analysis showed Fe and O peak, as well as Cl peak, meaning that cracks were affected by Cl ion. Failure of the tube was caused by chloride-induced stress corrosion cracking by thermal stress, high temperature, and localized enrichment of chloride ions.
Umbilicaria esculenta Extract Exhibits Antiwrinkle Activity by Suppressing ErbB2 Phosphorylation
Woo-Jin Sim,Yongeun Kim,Dong-Uk Jo,Ji Won Seo,Sangwon Chung,Hyo-Kyoung Choi,Kyung-Tack Kim,Tae-Gyu Lim 한국식품영양과학회 2022 Journal of medicinal food Vol.25 No.7
Umbilicaria esculenta (UE), an edible lichen, is widespread in northeast Asian countries, including China, Japan, and Korea. In the present study, we examined the antiwrinkle activity of UE. We observed that the UE extract (UEE) suppressed ultraviolet (UV)-induced matrix metalloprotein-1 (MMP-1) expression and reactive oxygen species (ROS) generation in a human keratinocyte cell line (HaCaT) and human skin tissue. In addition, UEE reversed the UV-induced decrease in collagen in the human skin tissue. Excessive and chronic UV exposure is a key factor underlying skin wrinkle formation via MMP-1 expression. As treatment with UEE disrupted the UV-activated mitogen-activated protein kinase (MAPK) signaling pathway, we applied an antibody array to unveil the underlying mechanism of UEE. Interestingly, UEE treatment inhibited ErbB2 phosphorylation, but not epidermal growth factor receptor phosphorylation, a heterodimerization partner with ErbB2. Furthermore, UEE treatment enhanced UV-suppressed phosphatase activity via ROS suppression. Collectively, our findings indicate that UEE enhances ErbB2 dephosphorylation to suppress UV-induced MMP-1 expression.
Subgap Density-of-States-Based Amorphous Oxide Thin Film Transistor Simulator (DeAOTS)
Yong Woo Jeon,Sungchul Kim,Sangwon Lee,Dong Myong Kim,Dae Hwan Kim,Jaechul Park,Chang Jung Kim,Ihun Song,Youngsoo Park,U-In Chung,Je-Hun Lee,Byung Du Ahn,Sei Yong Park,Jun-Hyun Park,Joo Han Kim IEEE 2010 IEEE transactions on electron devices Vol.57 No.11
<P>The amorphous oxide thin-film transistor (TFT)-oriented simulator [subgap Density of states (DOS)-based Amorphous Oxide TFT Simulator (DeAOTS)] is proposed, implemented, and demonstrated for amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs. It only consists of parameters having their physical meanings and is supplied with concrete techniques for parameter extraction. Among the physical parameters, the acceptor-like DOS <I>gA</I>(<I>E</I>) was experimentally extracted using the multifrequency <I>C</I>-<I>V</I> technique, whereas the donor-like DOS <I>gD</I>(<I>E</I>) and the doping concentration <I>ND</I> were extracted using numerical iterations. The simulation result reproduces the DOS and thin-film-thickness-dependence of dc <I>I</I>-<I>V</I> characteristics very well. Compared with the previously reported a-Si TFT models, the proposed DeAOTS model not only reflects the strong <I>V</I><SUB>GS</SUB> dependence of the effective mobility (μ<SUB>eff</SUB>) but also clarifies the relations between process-controlled DOS parameters and dc <I>I</I>- <I>V</I> characteristics based on experimentally extracted DOS parameters. Also, it sufficiently takes into account the peculiar situation of amorphous oxide TFTs where the free-carrier charge can be larger than the localized one out of the total induced charge. Moreover, it reproduces the measured electrical characteristics within the wide range of <I>V</I><SUB>GS</SUB>/<I>V</I><SUB>DS</SUB> with a single equation, not distinguishing the operation regions such as the subthreshold, linear, and saturation regimes.</P>
Absolute length measurement with the frequency comb of a femtosecond laser
Hyun, Sangwon,Kim, Young-Jin,Kim, Yunseok,Jin, Jonghan,Kim, Seung-Woo IOP Pub 2009 Measurement Science and Technology Vol.20 No.9
<P>We report exploiting the frequency comb of a femtosecond laser as a means of realizing the time-based SI definition of the meter for length metrology. Specifically, an external-cavity diode laser is continuously tuned to a stabilized frequency comb, and its output frequency is modulated over an extensive range to measure the absolute value of a given length by means of multi-wavelength optical interferometry. This approach could find applications in establishing practical length standards with a small amount of uncertainty directly traceable to time standards.</P>
상용 하이브리드 차량의 자동화 수동 변속기 변속 로직 개발
이상원(Sangwon Lee),우재진(Jaejin Woo),김영광(Youngkwang Kim),남광수(Kwangsoo Nam) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
This paper describes development of AMT(Automated Manual Transmission) shift control logic applied to the commercial HEV(Hybrid Electric Vehicle). Shift control algorithm is composed of shift sequence according to hybrid mode and collaborative control with HCU(Hybrid Control Unit), ECU(Engine Control Unit) and MG(Motor & Generator), position control of clutch & shift actuator. The proposed algorithm is proven to be successful by experiments performed vehicle.