• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.1084-1087
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• 1997

In this paper, we developed the micro NCT system for punching the thin plates, which is driven is driven by the standalone type microprocessor. In order to adjust the alignment between the punch and die in-situ punching procedures, the non-contact type laser sensor for measuring the burr and micro-driving system for punching die with using the differential screw are developed. The height of burr in four directions in the punched hole of test specimen are measured, and the measured data are transferred to the personal computer by RS232C serial communication technology. In the personal computer, by using the graphic user interface type monitoring program and data handling procedures which includes the filtering algorithms, the direction and length of movement of the die position is decided and these data are transferred back to the microprocessor. The microprocessor drives the micro positioning stage based on these data. Even if this method is not a perfect solution for the in-situ alignment in micro punching, but this alignment methodology is accomplished in the same stage just after the punching that we hope to solve the alignment problem in the punching system based on this technology.

• 농촌의학ㆍ지역보건
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• 제21권1호
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• pp.13-20
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• 1996

Paederus dermatitis caused by the contact of staphylinid beetles(Paederus fuscipes) body fluid(pederin) is characterized by linear erythematous vesicopustular lesions. An outbreak of dermatitis occurred at apartments located at the river side after rainy season in summer 1994. Authors surveyed 189 cases(94 males and 95 females) from 103 households reported at the apartment office in Kimcheon on September 1994. The results are as follows; 1. The causative agent of skin diseases was identified as Paederus fuscipes. 2. The attack rate of paederus dermatitis was 52.6% by households, and the residents in the middle floors of the apartments were attacked more frequently than those in other floors. All ages were affected. 3. The skin lesions developed by paederus were distributed on face(38.2%), neck(18.5%), shoulder and trunk(11.0%), arm and leg(10.3%), and back(6.6%). In 21 cases(15.4%), skin lesions were developed in multiple sites. 4. The apartments attacked by paederus was located near the sand and damp soil along the bank of the river. The fodder cultivating farm was located near the upper reaches of river, and a rice field and grape garden in the backyard of the apartment.

• 한국결정학회지
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• 제12권3호
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• pp.177-181
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• 2001

TiO₂박막의 초친수성 특성을 열처리에 따른 박막의 결정구조 변화와 연관지어 연구하였다. 박막은 Sol-Gel법을 이용하여 실리콘 (100)웨이퍼 위에 제조하였다. 1차 소결후, 500℃에서 후열처리한 시편은 anatase 상을, 1000℃에서 열처리한 시편은 rutile 상을 가지며 그 중판 온도인 750℃에서 열처리한 경우는 anatase와 rutile상이 혼재 되어 있다. 이 후열 처리한 시편들은 UV를조사하지 않아도 친수성을 보였고, 특히 750℃에서 열처리한 시편은 5°이하의 초친수성을나타내었다. 친수성을 가지는 시편들은 암실처리 중 서서히 퇴화되어 소수성을 띄게되지만, UV를 조사하면 1시간 이내에 급격히 초진수성을 회복하는 우수한 특성을 보였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1694-1700
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• 2007

In the electrified section, both of return current and signal current are flowing in the same rail in common. But signal current shall be allowed to flow in the specific track circuit and not in the other circuit while the traction return current shall come back to power sub-station. This paper presents measuring system that use both sensor and antenna. The aim of the system is to achieve the difference in current between the two rails and the presence of trimming capacitors. In order to improve the transmission level, trimming capacitors are connected between the two rails at constant spacing. To maintain the balance of traction return current, rails of both sides may be jointed by the so-called SVPMM. The traction return current is sometimes unbalanced owing to the ill-contact of SVPMM. In this paper, we propose a diagnosis method based on a short-circuited current(Icc), trimming capacitors and traction return current measured by Korail inspection vehicles. Whether Icc is good or bad depends not only on the presence of trimming capacitors but also on the unbalance of the traction return current.

• 한국전기전자재료학회논문지
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• 제22권3호
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• pp.269-276
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• 2009

Antimony doped tin oxide ($SnO_2:Sb$) films, which are used as the front contact and back reflector of thin film solar cells, have been deposited by d,c, magnetron sputtering. The dependence of electrical and optical properties of the films on the preparation conditions, such as $O_2$ gas ratio, substrate temperature, annealing temperature was investigated. The sputter gas composition was found to affect the properties of the films. With incorporating $O_2$ gas, the electrical and optical properties of films significantly were improved. The minimum resistivity and optical transmittance over 80 % in visible region were obtained at the oxygen concentration of 30 %, When the substrate temperature was higher, the resistivity of $SnO_2:Sb$ films was decreased, while the absorption edge shifted to shorter wavelength, indicating higher optical band gap. Heat treatment over $600^{\circ}C$ resulted in poorer electrical and optical properties due to SnO phase (102) plane.

• Journal of Mechanical Science and Technology
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• 제20권5호
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• pp.602-611
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• 2006

This paper proposes a locomotion pattern and a control method for biped robots with curved soles. First, since the contact point of a supporting leg may arbitrarily move back and forth on the ground, we derived the desired trajectory from a model called the Moving. Inverted Pendulum Model (MIPM) where the Zero Moment Point (ZMP) exists at the supporting point and can be moved intentionally. Secondly, a biped robot with curved soles is an under-actuated system since the supporting point contacting with a point on the ground has no actuator during the single supporting phase. Therefore, this paper proposes a computed-torque control for this under-actuated system using decoupled dynamic equations. A series of computer simulations with a 7-DOF biped robot with curved soles shows that the proposed walking pattern and control method are effective and allow the biped robot to walk fast and stably, and move more like human beings. Also, it is shown that the curved sole shape has superior energy consumption compared to flat soles, and greater efficiency in ascending and descending the stairs.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.383-388
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• 2001

Effects of particle property variation of cone crack shape according to impact velocity in silicon carbide materials were investigated. The damage induced by spherical impact having different material and size was different according to materials. The size of ring cracks induced on the surface of specimen increased with increase of impact velocity within elastic contact conditions. The impact of steel particle produced larger ring cracks than that of SiC particle. In case of high impact velocity, the impact of SiC particle produced radial cracks by the elastic-plastic deformation at impact regions. Also percussion cone was formed from the back surface of specimen when particle size become large and its impact velocity exceeded a critical value. Increasing impact velocity, zenithal angle of cone cracks in SiC material was linearly decreasing not effect of impact particle size. An empirical equation, $\theta=\theta_{st}-\upsilon_p(180-\theta_{st})(\rho_p/\rho_s)^{1/2}/415$, was obtained from the test data as a function of quasi-static zenithal angle of cone crack($\theta_{st}$), the density of impact particle(${\rho}_p$) and specimen(${\rho}_s$). Applying this equation to the another materials, the variation of zenithal angle of cone crack could be predicted from the particle impact velocity.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.319-319
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• 2010

칼코젠계 태양전지의 광흡수층으로 사용되는 CuInSe2은 직접천이형 반도체로 광흡수계수가 $1{\times}105cm-1$로 매우 높고, 전기광학적 안정성이 우수하여 실리콘 결정질 태양전지를 대체할 고효율 태양전지로 각광받고 있다. 광흡수층의 밴드갭 에너지가 증가하면 태양전지의 개방전압(Voc)이 증가하여 광변환 효율을 향상시킬 수 있으므로, CuInSe2에서 In의 일부를 Ga으로 치환하여 에너지 밴드갭의 변화를 주는 연구가 많이 진행되고 있다. 그러나 화합물내의 Ga 조성비가 증가하면 단락전류(Jsc), 충진률(fill factor)이 낮아져 태양전지 효율을 저하시키게 되므로 CIGS 박막의 적절한 화합물 조성비를 갖도록 최적조건을 확립하는 것이 매우 중요하다. 본 실험에서는 광흡수층 형성을 위해 Sputtering법으로 금속 전구체를 증착하고, 고온에서 셀렌화 열처리를 수행하는 Sequential process(2단계 증착법)를 이용하였다. soda-lime glass 기판에 Back contact으로 Mo를 증착하고, 1단계로 CuIn0.7Ga0.3 조성비의 타겟을 이용하여 Sputtering법으로 $0.5{\sim}2{\mu}m$ 두께의 CIG 전구체를 증착하였다. 2단계로 CIG 전구체의 셀렌화열처리를 통하여 CIGS 화합물 구조의 박막을 형성시켰다. 이때 형성된 CIGS 화합물 박막의 두께는 동일하게 함으로써, 열처리온도에 의한 박막의 구조변화를 비교하였다. 증착된 CIGS 박막은 고온 엑스선회절분석을 통해 증착 두께와 온도 변화에 따른 CIGS 층의 구조 변화를 확인하고, 동일한 증착조건으로 Buffer layer, Window layer, Grid 전극을 형성하여 태양전지셀 특성을 평가함으로써 CIGS 태양전지 광흡수층의 결정구조에 따른 광변환 효율을 비교하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 춘계학술대회
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• pp.786-788
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• 2013

몰리브덴(Molybdenum) 박막은 높은 전기전도성을 가진 금속으로 CIGS계 태양전지의 후면전극으로 많이 사용되고 있다. 스퍼터링법을 통해 증착되는 몰리브덴 박막의 경우, 전기 전도성 및 기판과의 밀착성은 스퍼터 전력 및 압력과 같은 공정 조건에 따라 변화된다. 본 연구에서는 DC 마그네트론 스퍼터링법을 이용하여 몰리브덴 박막을 Ar 가스 분위기에서 압력별로 증착하였다. SEM(scanning electron microscope), XRD(X-ray Diffraction), 4-point probe, 광반사율, Hall measurement를 이용하여 박막의 전기적, 구조적 특성을 분석하였다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.109-112
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• 1997

The Hydrodynamic performance of the trileaflet polymer prosthetic valves depends on the design of the leaflet and the physical properties of the leaflet membrane. In order to study the effect of leaflet membrane elasticity on the hemodynamic performance of trileaflet prosthetic valve, leaflet membranes are manufactured using two different polymers - Biospan and Tecoflex SG-93A. The hemodynamic performance parameters are measured under steady and physiological pulsatile flow, and compared with monoleaflet polymer valve(floating valve) and bileaflet mechanical valve(St. Jude Medical valve). Well designed trileaflet valve shows the lowest mean pressure drop among the tested valves. The trileaflet valves with Biospan membrane show lower pressure drop and back low comparing to those with Tecoflex membrane. More elastic membrane may provide wide opening area during systole and close membrane ree edge contact during diastole. Durability of trileaflet valves are also tested in vitro. Trileaflet valves with non-uniform membrane thickness ail within 17 days because of stress concentration. Trileaflet polymer valves with uniform membrane thickness perform well over 55 days without failure.