• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.772-776
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• 2001

The flow structures of turbulent shear layer behind oil fences with different tip configurations were investigated experimentally using flow visualization and PIV velocity field measurement. An oil fence was installed in a circulating water channel and the flow structure around the fence tip was mainly analyzed in this experiment. The four tip configurations tested in this experiment are knife edge; semi-circle edge, circular edge and rectangular edge. The 300 instantaneous velocity fields were measured using the single-frame PIV system and they were ensemble averaged to give the mean velocity field and spatial distribution of turbulent statistics. Free stream velocity was fixed at 10ms/sec and the corresponding Reynolds number based on the fence height was Re=4000. As a result, for the oil fence with rectangular edge, the streamwise velocity component was decreased. On the other hand it was increased for the oil fence with circular edge. For all four fences tested in this study, general flow pattern of the lower shear layer is analogous but the upper layer shows difference depending on the tip configurations. The oil fence with circular edge has more diffusive upper shear layer than that of the others. The shear layer of the oil fence with rectangular edge has relatively thin thickness. The oil fence with circular edge was found to be proper shape for tandem fence.

• 마이크로전자및패키징학회지
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• 제11권3호
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• pp.47-53
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• 2004

공정 Au-20Sn 솔더합금을 솔더링 시간과 온도를 달리하여 Ni위에서 솔더링하였다. 주사전자현미경 (SEM)을 사용하여 계면에 생성된 IMC의 조성, 상, 모양에 대해 조사하였다. 계면에는 $(Au,Ni)_3Sn_2$와 $(Au,Ni)_3Sn_2$의 두 가지 IMC가 생성되었다. 그 중 첫 번째 생성된 IMC인 $(Au,Ni)_3Sn_2$상은 솔더링 온도에 따라 모양의 변화가 관찰되었다. 이러한 모양의 변화로 인한 확산통로수의 변화는 모든 솔더링 온도에서 거의 비슷한 IMC 두께를 가지도록 한다. IMC, $(Au,Ni)_3Sn_2$상의 모양변화는 온도 증가에 의한 생성엔탈피의 감소 때문인데, 이는 Jackson's parameter로써 잘 설명될 수 있다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.74-78
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• 2003

본 논문에서는 금속의 표면 플라즈몬 공명으로 인한 금속-유전체 경계면에서의 국소적 전자기장의 강화 효과를 이용하여 표면 플라즈몬을 유발하는 금 박막을 유리 기판위에 증착하고, 프리즘 커플러를 이용한 소산장의 공명 흡수현상을 이차원 영상 으로 얻었다. 특히 DNA/단백질 칩 등 향후 가능한 다채널 시스템에의 응용을 고려하여11-MUA, 11-MUOH 등 자기조립 단분자막(SAM)을 크롬 마스크와 리토그래피, 그리고 Shadow mask와 광 산화반응을 이용하여 금 표면 위에 패터닝 하였다. 텅스텐-할로겐 램프와 중심파장이 ${\lambda}_0=633$ nm의 대역통과 필터를 사용하여 이 평행광을 프리즘 커플러에 입사시켜 반사되어 나오는 반사광의 이차원 영상을 얻었다. 이와는 별도로 ${\lambda}_0=633$ nm의 레이저를 이용하여 단분자막이 코팅되어 있을 때와 없을 때의 공명각의 변화를 관찰하였다. 얻어진 이차원 영상의 위치에 따른 화소 값의 변화를 단분자 막의 두께의 변화에 따라 보정하고, 알려진 매질의 SPR 특성을 Fresnel 방정식에 따라 이론적으로 계산하면 다채널 표면 영상으로부터 항원-항체 등 단백질의 결합 정도를 정량적으로 측정할 수 있다.

• 대한기계학회논문집B
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• 제34권1호
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• pp.61-66
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• 2010

최근 본 연구그룹은 국소적인 종횡비 증가를 기반으로 수평 분리벽 없이 검체의 3 차원 집속을 구현하는 3 차원 유체역학 집속 미세유체 장치(3D-HFMD)를 제안한 바 있다. 본 논문에서는, 다양한 형상 및 유동 조건에 따른 3D-HFMD 의 3 차원 유체역학 집속 거동 영향에 대한 연구를 수행하였다. 이에 3 차원 전산유체역학(CFD) 시뮬레이션을 통해, 형상 및 유동 조건 변화에 대한 기존의 미세유체 장치와 본 연구 그룹이 제안한 3D-HFMD의 3 차원 유체역학 집속의 매개변수 연구를 수행하였다. 수행된 CFD 시뮬레이션 결과를 바탕으로 3 차원 집속을 위한 채널 형상 디자인 및 유동 조건을 제안하였다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1996년도 춘계학술대회
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• pp.175-175
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• 1996

The spinal dorsal horn is the area where primary afferent fibers terminate and cutaneous sensory information is Processed. A number of putative neurotransmitter substances, including excitatory and inhibitory amino acids and peptides, are present in this region and sites and cellular mechanisms of their actions have been a target of numerous studies. In this study, single neurons were acutely isolated and the properties of whole cell current and responses to excitatory and inhibitory neurotransmitters were studied by the patch clamp method. Young rats (7-14 days) were anesthetized with diethyl-ether, and the lumbar spinal cord was excised and cut transversely at a thickness of 30$\mu\textrm{m}$ by Vibroslicer. The treatment of spinal slices with low concentration of proteases (pronase and thermolysin 0.75 mg/$m\ell$) and mechanical dissociation yielded isolated neurons with near intact morphology. Multipolar, ellipsoidal and bipolar, and pyramidal cells were shown. By applying step voltage pulses to neurons held at -70 mV, two types of inward currents and one outward currents observed. The fast activating and inactivating inward current was the Na$\^$+/ current because of its fast kinetics and blocking by 0.5${\mu}$M TTX, a specific blocker of Na$\^$+/ channel. The second type of inward currents were sustained. Based on their kinetics and current-voltage relations, it was likely that the second type of inward current was the voltage-dependent Ca$\^$2+/ current. In the presence of TTX, the steady-state currents mainly represented outward K$\^$+/ current which looked like the delayed rectifier K$\^$+/ current. In addition, the membrane currents produced by agonist of excitatory amino acid (EAA) receptor and the endogenous transmitter candidate L-glutamate were recorded in isolated whole-cell voltage clamped neurons as well as responses to inhibitory amino acids (${\gamma}$-amino butyric acid, glycine). Drugs were applied by a method that allows complete exchange of the solution within 1 sec; an infinite number of solutions can be applied to a single cell.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.379-379
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• 2013

본 논문에서는 Normal ink jetting 공법으로 OTFT를 제작할 때 coffee stain effect에 의해서 반도체 소자의 특성이 저하되는 것을 극복하기 위해서 동일한 위치에 동일한 부피로 Droplet을 형성하는 Multiple ink jetting 공법을 통해 TIPS pentacene 결정의 Morphology와 전기적 특성이 어떻게 변화하는지 알아 보았다. Multiple ink jetting의 drop 횟수가 증가할수록 coffee stain effect에 의해서 형성된 가운데 영역의 Dendrite grain이 점점 작아지다가 7 Drops 이후로는 Big grain 만 남게 되었다. Active layer의 표면 Roughness는 drop 횟수가 증가할수록 낮아지다가 일정 count 이후로는 다시 높아지는 것을 확인할 수 있었다. 전계 이동도(mobility)는 drop 횟수가 증가할수록 커지다가 일정 count 이후로는 saturation되는 것을 확인할 수 있었다. Multiple ink jetting에 의해서 만들어진 OTFT 소자의 전계 이동도(mobility)는 1 drop과 10 drops에서 각각 0.0059, 0.036 cm2/Vs 로 6배 정도 차이가 있었다. 이것은 첫 drop에 의해 만들어진 가운데 Dendrite grain 영역이 Multiple ink jetting을 반복하면서 점점 작아지게 되어 사라지고 두꺼운 Grain 영역만 남게 된 것으로 판단된다. Vth 와 On/Off ratio는 1 drop과 10 drops에서 각각 -3 V, -2 V 그리고 $3.3{\times}10^3$, $1.0{\times}10^4$를 보였다. OTFT의 substrate로 Flexible한 polyethersulfone (PES) 기판을 사용하였고, 절연체로 Spin coating된 Poly-4-vinylphenol (PVP)가 사용되었으며, Gate 및 Source/Drain 전극은 Au를 50 nm 두께로 증착하였다. Channel의 width와 length는 각각 100 um, 40 um 였고, Gate 전극 위에 Active layer를 형성한 Bottom gate 구조로 제작되었다. Ink jet으로 제작된 TIPS pentacene의 결정성은 x-ray diffraction (XRD)와 광학 현미경으로 분석하였고 Thickness profile은 알파스텝 측정기를 이용하였으며, OTFT의 전기적 특성은 Keithley-4,200을 사용하여 측정하였다.

• Ocean and Polar Research
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• 제26권4호
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• pp.595-606
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• 2004

Hydrographic survey in the Korea Strait has long history that has begun in August 1917 at the Busan - Tsushima cross section, still continues to date. However, chemical properties of bottom cold water found exclusively in the western channel of the Korea Strait during summer did not receive much scientific attention. The aim of the study is to decipher the enigmatic origin of the Korea Strait Bottom Cold Water (KSBCW) in terms of chemical properties. The physicochemical properties of the KSBCW are extracted from the CREAHS II hydrographic data. OMP method was applied to analyze origin of the KSBCW quantitatively. The KSBCW is well defined by low temperature below $10^{\circ}C$. The cold waters exhibited the local presence near the coast at about 120m depth with a thickness of 20m to 30m. The cold water was characterized by relatively cold, saline and higher chemical concentrations than adjacent waters. The KSBCW seems to have different origin kom that of the coastal upwelled waters at the Ulgi-Gampo because it is saline, denser and contains considerably less dissolved oxygen than upwelled waters. The physicochemical properties are reported to have noticeable annual variations which suggest the complex origin of the KSBCW. OMP analysis show that the KSBCW is a mixture of three water types; TMW (24%), ESIW (36%) and ESPW (40%). Relationship between the KSBCW and the east Sea circulation is traced by mapping the water masses that have similar T, S and DO of KSBCW. The result showed that the KSBCW is most possibly an extension of southward flowing coastal intermediate waters. Front these results, we expect that the monitoring KSBCW will provide us valuable information about the East Sea circulation.

• Steel and Composite Structures
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• 제27권5호
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• pp.537-543
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• 2018

Mechanical shear connectors are commonly used to transfer longitudinal shear forces across the steel-concrete interface in composite beams. Steel pipe as a new shear connector is proposed in this research and its performance to achieve composite strength is investigated. Experimental monotonic push-out tests were carried out for this connector. Then, a nonlinear finite element model of the push-out specimens is developed and verified against test results. Further, the finite element model is used to investigate the effects of pipe thickness, length and diameter on the shear strength of the connectors. The ultimate strengths of these connectors are reported and their respective failure modes are discussed. This paper comprises of the push-out tests of ten specimens on this shear connector in both the vertical and horizontal positions in different reinforced concretes. The results of experimental tests are given as load-deformation plots. It is concluded that the use of these connectors is very effective and economical in the medium shear demand range of 150-350 KN. The dominant failure modes observed were either failure of concrete block (crushing and splitting) or shear failure of pipe connector. It is shown that the horizontal pipe is not as effective as vertical pipe shear connector and is not recommended for practical use. It is shown that pipe connectors are more effective in transferring shear forces than channel and stud connectors. Moreover, based on the parametric study, a formula is presented to predict the pipe shear connectors' capacity.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 추계학술발표대회 논문집
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• pp.226-231
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• 2008

The heat transfer characteristics of a solar high-temperature receiver with heat pipes was investigated by numerical simulation. The concentration ratio of the solar receiver ranges 1000 and the concentrated heat is required to be transported to a certain distance for specific applications. This study deals with internal geometry variation of a solar receiver incorporating high-temperature heat pipe. The isothermal characteristics in the receiver section is of major concern. The diameter of the solar thermal receiver was 120 mm and the length was 400 mm. The angle of receiver end wall was varied between $0^{\circ}$ and $45^{\circ}$. The wall thickness of the heat pipe channel was 4mm and 48 axial channels of the same dimensions were attached to the outer wall of the receiver with even spacing in the circumferential direction. The channels are changed to high-temperature sodium heat pipes. Commercial softwares were employed to deal with the radiative heat transfer inside the receiver cavity and the conduction heat transfer along the channels. The numerical results are compared and analyzed from the view Point of high-temperature solar receiver.

• 대한전자공학회논문지
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• 제25권11호
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• pp.1367-1372
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• 1988

본 논문은 최적의 고출력용 (GaAl) As/GaAs CSP-LOC 레이저 다이오드 구조를 설계하기 위하여 컴퓨터 시뮬레이션 하였다. 실험 데이터를 근거로한 레이저다이오드의 설계변수로 각 층의 두께, 흡수계수, 스트라이프 폭등이 사용되었고 활성층(d2)와 광 도파로층(d3)의 두께가 각각 0.08um, 0.5um일때와 0.1um, 0.4um일때 최적의 안정된 고출력용 CSP-LOC 구조를 얻었다. 따라서 본 노문에서는 실용적인 반도체레이저의 컴퓨터 시뮬레이션 프로그램을 개발하였고 임의의 재료를 갖는 CSP-LOC 구조에 이 프로그램의 적용이 가능하다.