• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2002년도 학술대회지
• /
• pp.687-690
• /
• 2002

Multimode boundary-layer transition on a NACA0012 airfoil is experimentally investigated under periodically passing wakes and the moderate level of free-stream turbulence. The periodic wakes are generated by rotating circular cylinders clockwise or counterclockwise around the airfoil. The free-stream turbulence is produced by a grid upstream of the rotating cylinder, and its intensity(Tu) at the leading edge of the airfoil is $0.5\;or\;3.5\;{\%}$. The Reynolds number ($Re_c$) based on chord length (C) of the alrfoil is $2.0{\times}10^5$, and Strouhal number ($St_c$) of the passing wake is about 0.7. Time- and phase-averaged streamwise mean velocities and turbulence fluctuations are measured with a single hot-wire probe, and especially, the corresponding wall skin friction is evaluated using a computational Preston tube method. The wake-passing orientation changes pressure distribution on the airfoil in a different manner irrespective of the free-stream turbulence. Regardless of free-stream turbulence level, turbulent patches for the receding wakes propagate more rapidly than those for the approaching wake because adverse pressure gradient becomes larger. The patch under the high free-stream turbulence ($Tu=3.5{\%}$) grows more greatly in laminar-like regions compared with that under the low background turbulence ($Tu=0.5{\%}$) in laminar regions. The former, however, does not greatly change the original turbulence level in the very near-wall region while the latter does it. At further downstream, the former interacts vigorously with high environmental turbulence inside the pre-existing transitional boundary layer and gradually lose his identification, whereas the latter keep growing in the laminar boundary layer. The calmed region is more clearly observed under the lower free-stream turbulence level and for the receding wakes. The calmed region delays the breakdown further downstream and stabilizes more the boundary layer.

• 복식문화연구
• /
• 제24권1호
• /
• pp.54-66
• /
• 2016

This paper examines the transition of the Hungarian men's costume. Transition of the Hungarian men's costume can be divided into pre-eighteenth century, eighteenth century, and since the nineteenth century. Hungarian costume was derived from the Magyar who settled in Hungary in the ninth century. Hungry had begun to accept Western culture in the tenth century, so when the prototype of Hungarian costume was completed, it consisted of Dolman, Mente, pants, and boots combining traditional Magyar style with Western European style. In particular, Dolman shows the uniqueness of the Hungarian men's costume; it has a high, stand-up collar in the back center, closes on the left, has a right front plate with a diagonal cut at the waist, and a wide front closure. In the eighteenth century, Hungarian men's costumes played an important role in displaying national pride while living under the oppression of the Habsburg Empire. In particular, Dolman was worn as a uniform at the battle of independence (1703~1710). This dress of male courtiers became the distinctive style of the eighteenth century and then became the basic style of men's costumes. Since the nineteenth century, Hungarian men's costumes have acted as an means to promote the national consciousness of Hungary through the Citizen Revolution (1848), the War of Independence (1849), and the formation of the Dual Empire (1867). Looking at evolution of the Hungarian men's dress style, it reveals that resistance and struggles against other nations, a history of aggression, and living under oppressed are factors that impact on important clothing transitions.

• 대한기계학회논문집B
• /
• 제30권9호
• /
• pp.921-928
• /
• 2006

Wake-induced boundary-layer transition on a NACA0012 airfoil with zero angle of attack is experimentally investigated in periodically passing wakes under the moderate level of free-stream turbulence. The periodic wakes are generated by rotating circular cylinders clockwise or counterclockwise around the airfoil. The free-stream turbulence is produced by a grid upstream of the rotating cylinder, and its intensities $(Tu_{\infty})$ at the leading edge of the airfoil are 0.5 and 3.5%, respectively. The Reynolds number (Rec) based on chord length (C) of the airfoil is $2.0{\times}10^5$, and Strouhal number (Stc) of the passing wake is about 1.4. Time- and phase-averaged streamwise mean velocities and turbulence fluctuations are measured with a single hot-wire probe, and especially, the corresponding wall skin friction is evaluated using a computational Preston tube method. The patch under the high free-stream turbulence $(Tu_{\infty}=3.5%)$ grows more greatly in laminar-like regions compared with that under the low turbulence $(Tu_{\infty}=0.5%)$ in laminar regions. The former, however, does not greatly change the turbulence level in very near-wall region while the latter does it. At further downstream, the former interacts vigorously with high environmental turbulence inside the pre-existing transitional boundary layer and gradually loses its identification, whereas the latter keeps growing in the laminar boundary layer. The calmed region is more clearly observed under the lower free-stream turbulence level and with the receding wakes.

• 한국재료학회지
• /
• 제11권6호
• /
• pp.508-511
• /
• 2001

사파이어 단결정의 취성-연성전이에 대한 실험을 행하였다. 사파이어 단결정의 취성-연성전이온도는 변형율 3.3$\times$ $10^{-5}$/sec에서 $1000\pm$$25^{\circ}C$ 그리고 변형률 3.3$\times$$10^{-5}$/sec에서는 1100$\pm$26$^{\circ}C$이었다. 취성-연성전이모델을 이용하여 Prism Plane slip {1120} <1100> 전위속도의 활성화에너지를 계산하였으며, 그 결과 활성화에너지는 4.6$\pm$2.3eV의 범위를 가졌다. 이 활성화에너지는 에치-퍼트법을 이용하여 전위속도측정으로부터 구한 결과치 3.8eV와 유사하였다.

• 대한본초학회지
• /
• 제31권1호
• /
• pp.33-40
• /
• 2016

Objectives : Liver is one of the largest organs in the human, and has a function of detoxification and energy sensing to prevent severe disease. Paeoniae radix has been used to treat a variety of liver diseases such as hepatitis and chronic hepatic failure. Although P. radix has been used as an medicinal herb for a long time, the effects of P. radix on severe oxidative stress and its action mechanism on the liver was not clearly verified.Methods : This study investigated the protective effects of P. radix extract (PRE), and the underlying mechanism of its action in the liver. tert-butyl hydroperoxide (t-BHP) and carbon tetrachlroride (CCl₄) were used to induce oxidative stress in the HepG2 hepatocyte cell line and Sprague-Dawley rats, respectively.Results : t-BHP significantly induced cell death and ROS production in HepG2 cell, as indicated by MTT and FACS analysis. However, pretreatment of PRE inhibited a decrease in cell viability and H₂O₂ production in the HepG2 cells. PRE also blocked the ability of t-BHP to damage in mitochondrial membrane transition. More importantly, PRE induced Nrf2 activation and antioxidant Phase II enzyme, which may have a role in the effects of PRE. In mice, PRE inhibited the liver damage induced by CCl₄.Conclusions : PRE inhibited oxidative stress and hepatic damages as mediated with Nrf2 activation. This study unveil, in part, the effect and mechanism of old medicinal herb, P. radix.

• 실천공학교육논문지
• /
• 제5권2호
• /
• pp.109-115
• /
• 2013

본 논문에서는 컴퓨터 비전을 이용한 강의 도우미 시스템을 제안한다. 강의자가 강의를 진행하며 사용하는 강의 노트 및 관련 동영상 등 다양한 강의 컨텐츠를 사용할 때, 컨텐츠 전환 등 컴퓨터 조작으로 인해 강의의 끊김이 유발된다. 제안하는 시스템에서는 강의 도중 강의 컴퓨터에 대한 조작이 필요할 때, 보드에 미리 정해진 기호를 그려 넣고 시스템이 이를 인식하여 해당 조작을 수행함으로써 강의 끊김 없이 손쉽게 강의를 이끌어 가도록 도와준다. 제안된 강의 도우미 시스템에서는 임의의 기호를 인식하기 위해 모양 문맥이라는 특징 표현자를 사용한다.

• Computers and Concrete
• /
• 제1권3호
• /
• pp.261-284
• /
• 2004

Two enhancements to a recently developed plastic-damage-contact model for concrete are presented. The model itself, which uses planes of degradation that can undergo damage and separation but that can regain contact according to a contact law, is described. The first enhancement is a new damage evolution function which provides a completely smooth transition from the undamaged to the damaged state and from pre-peak to post-peak regions. The second is an improved contact function that governs the potential degree of contact with increasing opening on a crack plane. The use of a damage evolution function with a pre-peak has implications for the consistent tangent matrix/stress recovery algorithm developed for the model implementation, and amendments to this algorithm to accommodate the new function are described. A series of unpublished experimental tests on notched specimens undertaken in Cardiff in the mid 1990s are then described. These include notched beam tests as well as prismatic and cylindrical torsion tests. The tests are then considered in three dimensional finite element analyses using the modified Craft model implemented in the finite element program LUSAS. Comparisons between experimental and numerical data show reasonable agreement except that the numerical simulations do not fully describe the latter stages of the softening responses for the torsion examples. Finally, it is concluded that the torsion tests described provide useful benchmark examples for the validation of three-dimensional numerical models for concrete.

• 대한한의학원전학회지
• /
• 제28권1호
• /
• pp.195-206
• /
• 2015

Objectives : Before Liver, Heart, Spleen, Lung, Kidney was widely accepted as Five Viscera, there had been several former types of Viscera system in pre-Western Han era. Above them, the Five Viscera system consisted of Liver, Heart, Stomach, Lung, Kidney was not yet hardly studied. So we tried to prove it's existence and tried to find it's historical context. Material and Methods : Via preceding research analysis, 6 books were selected as research material, and some other pre-Eastern Han dynasty classics were also analyzed. Results : We found direct evidence of above Five Viscera system in Zhuixingxun (墜形訓) in Huainanzi (淮南子), Wusemaizhen (五色脈診), and Western Han dynasty lacquer figure with meridian-points (excavated in Laoguanshan, Chengdu, China). Other clues showing existence of above Five Viscera system was also found in Yinyangshiyimaijiujing (陰陽十一脈灸經), Pianquecanggongliechuan (扁鵲倉公列傳). The rising of above Five Viscera system was related to physiological viewpoint transition of viscera in Western Han dynasty. Conclusions : In Western Han dynasty there was another Viscera System consisted of Liver, Heart, Stomach, Lung, Kidney.

• 천문학회보
• /
• 제46권2호
• /
• pp.51.1-51.1
• /
• 2021

Merger shocks with M_s < ~ 3 - 4 have been detected in galaxy clusters through radio observations of synchrotron radiations emitted from cosmic-ray (CR) electrons. The CR electrons are believed to be produced by the so-called diffusive shock acceleration (DSA) at the merger shocks. To describe the acceleration of electrons, the injection into DSA has to be understood. Recent studies have showed that electrons could be energized through stochastic shock drift acceleration (SSDA), a mechanism mediated by multi-scale plasma waves at shock transition zone. However, such preacceleration process seems to be effective only at the supercritical shocks with M_s > ~ 2.3, implying that further studies should be done to explain radio relics with weaker shocks. In this talk, we present the results obtained by fully kinetic 2D particle-in-cell (PIC) simulations, which include pre-existing suprathermal electrons possibly ejected from active galactic nuclei (AGNs) or produced by previous episodes of turbulence/shocks. The simulations indicate that the pre-existing electrons enhance the upstream plasma waves in shocks with M_s < ~ 2.3. However, the wavelength of such waves is not long enough to scatter off suprathermal electrons and energize them to the injection momentum for DSA. Hence, we conclude that preexciting suprathermal electrons alone would not solve the problem of electron acceleration at radio relic shocks.

• 한국사회복지학
• /
• 제69권3호
• /
• pp.193-212
• /
• 2017

본 연구의 목적은 산업재해를 경험한 근로자의 경제활동형태 변동과 그 특성을 기술하고, 산재근로자의 노동시장이행과 관련하여 산재보상서비스를 비롯한 영향 요인이 무엇인지 탐색하는 것이다. 이를 위해 산재보험패널 1~3차(2013년-2015년)자료를 활용하여, 요양을 종료한 1,668명의 산재근로자를 대상으로 분석하였다. 연구결과는 첫째, 한번이라도 원직장 복귀를 경험한 사람은 36.9%, 재취업 경험자는 51.5%, 미취업 경험자는 36.9%였다. 경제활동형태 전이확률은 현재 원직장 복귀자가 다음 기에도 원직장을 유지할 확률은 88.1%, 재취업자의 재취업 유지 확률 88.9%, 미취업자가 다음 기에도 미취업자가 될 확률은 60.0%로 나타났다. 둘째, 경제활동형태 변화에서 재취업 대비 원직장 복귀에 유의미한 영향을 미치는 요인은 성별, 연령, 학력, 요양기간, 현재 업무수행능력, 산재전 직장규모, 근무기간, 종사상 지위 중 임시직, 일용직 그리고 직업훈련 총 횟수였다. 재취업 대비 미취업을 선택할 확률에 유의미한 영향을 주는 요인은 성별, 연령, 장해등급, 요양기간, 현재 업무수행능력, 산재 전 근로기간, 직업재활서비스 이용 경험이었다. 분석결과를 토대로 산재근로자의 직업복귀와 노동시장이행을 지원하기 위한 논의점을 제시하였다.