• 반도체디스플레이기술학회지
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• 제19권3호
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• pp.30-35
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• 2020

A microlens has been fabricated by various methods such as a thermal reflow, hot embossing, diamond milling, etc. However, these methods require a relatively complex process to control the microlens shape. In this work, we report on a simple and cost-effective method to fabricate a cylindrical microlens (CML), which can diffuse light widely. We have employed a slot-die head with the dual plate (a meniscus guide with a protruded μ-tip and a shim with a slit channel) for coating of a narrow stripe using poly(methyl methacrylate) (PMMA). We have shown that the higher the coating gap, the lower the maximum coating speed, which causes an increase in the stripe width and thickness. The coated PMMA stripe has the concave shape. To make it in the shape of a convex microlens, we have applied the thermal reflow method. When the stripe thickness is small, however, its effect is negligible. To increase the stripe thickness, we have increased the number of repeated coating. With this scheme, we have fabricated the CML with the width of 223 ㎛ and the thickness of 7.3 ㎛. Finally, we have demonstrated experimentally that the CML can diffuse light widely, a feature demanded for light extraction efficiency of organic light-emitting diodes (OLEDs) and suppression of moiré patterns in displays.

• 천문학회보
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• 제38권1호
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• pp.49.1-49.1
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• 2013

We have been carrying out near-infrared (NIR) spectroscopy as well as [Fe II] narrow band imaging observations of Cassiopeia A supernova remnant (SNR). In this presentation, we describe the spectral classification of the iron knots around the SNR. From eight long-slit spectroscopic observations for the iron-bright shell, we identified a total of 61 iron knots making use of a clump-finding algorithm, and performed principal component analysis in an attempt to spectrally classify the iron knots. Three major components have emerged from the analysis; (1) Iron-rich, (2) Helium-rich, and (3) Sulfur-rich groups. The Helium-rich knots have low radial velocities (${\mid}v_r{\mid}$ < 100 km/s) and radiate strong He I and [Fe II] lines, that match well with Quasi-Stationary Flocculi (QSFs) of circumstellar medium, while the Sulfur-rich knots show strong lines of oxygen burning materials with large radial velocity up to +2000 km/s, which imply that they are supernova ejecta (i.e. Fast-Moving Knots). The Iron-rich knots have intermediate characteristics; large velocity with QSF-like spectra. We suggest that the Iron-rich knots are missing "pure" iron materials ejected from the inner most region of the progenitor and now encountering the reverse shock.

• Design & Manufacturing
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• 제15권3호
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• pp.26-31
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• 2021

In this study, laser-induced periodic surface structure (LIPSS) was fabricated on Ni, Si, and GaAs samples using a flat-top beam with a uniform energy distribution that was fabricated using a Gaussian femtosecond laser with a mechanical slit and tube lens. Unlike the Gaussian beam, the flat-top beam has a uniform beam profile, therefore the center and the periphery of the fabricated LIPSS have similar line periodicity. In addition, LIPSS was obtained not only in metals but also in metalloids and metals and metalloid compounds by using the narrow pulse width characteristic of a femtosecond laser.

• Earthquakes and Structures
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• 제23권1호
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• pp.59-73
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• 2022

In this study, the seismic behavior of an all-steel buckling-restrained (AB) steel plate shear wall (SPSW) with incline slits under fire and cyclic loading was investigated. ABSPSW was composed of two thin steel infill plates with a narrow distance from each other, which were embedded with incline slits on each plate. These slits were in opposite directions to each other. The finite element (FE) numerical model was validated with three test specimens and after ensuring the modeling strategy, the parametric study was performed by considering variables such as wall plate thickness, slit width, strip width between two slits, and degree of temperature. A total of 256 FE numerical models were subjected to coupled temperature-displacement analysis. The results of the analysis showed that the high temperature reduced the seismic performance of the ABSPSW so that at 917℃, the load-bearing capacity was reduced by 92%. In addition, with the increase in the temperature, the yield point of the infill plate and frame occurred in a small displacement. The average decrease in shear strength at 458℃, 642℃, and 917℃ was 18%, 46%, and 92%, respectively, compared to the shear strength at 20℃. Also, with increasing the temperature to 917℃, ductility increased by an average of 75%

• 멤브레인
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• 제27권2호
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• pp.167-181
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• 2017

그래핀 기반 소재는 높은 가공성과 초박성으로 인하여 분리막 소재로서 각광받고 있다. 본 연구에서는, 스핀 코팅법을 이용하여 제조된 산화그래핀 분리막의 기체 투과 거동을 평가하였다. 산화그래핀 분리막의 구조는 산화그래핀의 크기와 산화그래핀 용액의 pH 조절을 통하여 조절될 수 있다. 산화그래핀의 크기가 작을수록 굴곡률이 작아짐에 따라 분리막의 기체 투과도 및 선택도가 증가하는 경향을 보인다. 또한 산화그래핀에서의 기체 투과 거동은 적층된 산화그래핀 사이의 채널크기에 따라 영향을 받는다. 특히 산화그래핀 분리막의 좁은 기공과 이산화탄소 선택적인 산화그래핀 자체의 특성으로 인하여 산화그래핀 분리막은 이산화탄소에 대한 높은 투과도 및 선택성을 가지며, 이는 이산화탄소 포집에 적합한 특성을 가진다. 이러한 산화그래핀 분리막의 특이한 기체 투과 거동은 흡착-촉진 확산 거동(표면 확산 기작)으로 설명될 수 있다. 본 연구를 통하여 이산화탄소 선택성 분리막 소재 설계와 슬릿 형태의 기공과 적층 구조를 가진 분리막을 통한 기체 투과 거동 연구가 활발히 이루어질 것으로 기대한다.

• 패션비즈니스
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• 제21권1호
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• pp.58-73
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• 2017

The purpose of this study was to examine the need of the eyelash design area and the changes of an eye image according to eyelash design. Methodology included both a theoretical research and an empirical research. The theoretical research reviewed previous researches and technical books. The empirical research divided eye shapes, complemented the defect of eye shapes, and examined resulting image changes. A mechanical way was performed for treatment because it was more efficient than a manual way. A J-curl type was used. Eye length was divided into five and the point was determined. The length and density of curl were changed in each point to maximize a treatment effect. As a result, eye images were changed as follows. First, round eyes became stable. Slit eyes became vivid and soft. Wide-set eyes became intelligent and narrow-set eyes became smooth. Large eyes were naturally gradated and small eyes became larger. Double-eyelid eyes became stable and elegant and single-eyelid eyes became gentle and soft. Bulging eyes became easy and soft and sunken eyes became smooth. Peaked eyes became gentle and soft and sleepy eyes became strong and vivid. Based on the findings, eyelash design can play a role in changing an image according to eye shapes. In particular, a speed eyelash extension device to extend eyelash can reduce working hours and gradate only by angle control. It can complement the defect of eyes according to the design of each shape and change into a better image.

• 한국화재소방학회논문지
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• 제31권4호
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• pp.52-58
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• 2017

본 연구에서는 급기가압에 따른 건축물 내부의 공기유동에 대한 수치해석을 수행하고 거실, 부속실 및 계단실 간의 차압분포 및 유동 특성을 분석하였다. 유동 해석은 유효누설면적을 측정하기 위해 제작된 누기율 시험설비에 대하여 수행하였으며, 급기가압에 따른 각 실의 압력 및 유속분포 등을 분석하였다. 본 해석에서 공기의 누설은 유효누설면적을 갖는 얇은 틈새를 방화문과 창문에 위치시키는 방법으로 모사하였다. 이러한 방법을 이용한 해석은 계단실과 부속실 간의 차압에 대한 기존 실험의 결과를 적절히 예측하였다. 해석 결과를 통해 국부적인 누설이 급기가압 제연 설비의 전체적인 유동 패턴 및 압력 분포에 큰 영향을 미치지 않음을 확인하였다. 거실-부속실 문 단면에서의 평균속도가 방연풍속에 대한 국가화재안전기준을 만족하였으나 문의 상부와 같은 국부적인 위치에서 부속실로의 유출이 발생할 수 있음을 확인하였다.

• 대한기계학회논문집B
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• 제27권8호
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• pp.1023-1032
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• 2003

The effect of local forcing on the separated flow over a backward-facing step is investigated through hot-wire measurements and flow visualization with multi-smoke wires. The boundary layer upstream of the separation point is laminar and the Reynolds number based on the free stream velocity and the step height is 13800. The local forcing is given from a slit located at the step edge and the forcing signal is always defined when the wind tunnel is in operation. In case of single frequency forcing, the streamwise velocity and the reattachment length are measured under forcing with various forcing frequencies. For the range of 0.010〈S $t_{\theta}$〈0.013, the forcing frequency component of the streamwise velocity fluctuation grows exponentially and is saturated at x/h = 0.75 , while its subharmonic component grows following the fundamental and is saturated at x/h = 2.0. However, the saturated value of the subharmonic is much lower than that of the fundamental. It is observed that the vortex formation is inhibited by the forcing at S $t_{\theta}$ = 0.019 . For double frequency forcing, natural instability frequency is adopted as a fundamental frequency and its subharmonic is superposed on it. The fundamental frequency component of the streamwise velocity grows exponentially and is saturated at 0.5 < x/ｈ < 0.75, while its subharmonic component grows following the fundamental and is saturated at x/ｈ= 1.5 . Furthermore, the saturated value of the subharmonic component is much higher than that for the single frequency forcing and is nearly the same or higher than that of the fundamental. It is observed that the subharmonic component does not grow for the narrow range of the initial phase difference. This means that there is a range of the initial phase difference where the vortex parring cannot be enhanced or amplified by double frequency forcing. In addition, this effect of the initial phase difference on the development of the shear layer and the distribution of the reattachment length shows a similar trend. From these observations, it can be inferred that the development of the shear layer and the reattachment length are closely related to the vortex paring.

• 복식
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• 제56권4호
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• pp.65-81
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• 2006

This is the study on the costumes of Parthian Period in Persia which had powerful influences on the Occidental and Western cultures in B.C 3 to A.D 3. With different types of Parthian costumes in each period, this study shows what types of costumes people used to wear and how they were co-related with its surrounding cultures. The ancient costumes of Korea had something to do with the elements of the Northern part at that time. To make an intensive study of Korean ancient costumes, these Parthian costumes which are known to those of northern nomadic tribes are studied to provide basis elements for study between the Korean styles and the exotic styles. The basic forms of the Parthian styles were jackets and trousers. They consisted of three kinds of jackets such as those to be adjusted In the front, tunics and coats. As for trousers, they were divided into three types such as those with horizontal pleats, round-side pleats and vertical pleats. 1) The jacket to be adjusted in the front was long enough to reach the hip and fit the body reasonably tight, and its neckline was shaped into V-type. It was a very popular style among the people of high and low classes. 2) The tunics had narrow sleeves. It was a one-piece pattern which reached the knees. It was settled with a belt on the waist. Its neckline was shaped into the round but its slit was not cleat. Its styles were into tight-fit and drapery ones. 3) The coats were almost similar to the jacket to be adjusted in the front with short length, but they were entirely long and open. They appeared later than the short jackets and the people of high class seemed to wear these styles. 4) 1'rousers with horizontal pleats - They had almost horizontal pleats on them, and they were a little tight. They seemed to be the early style in the Parthian period. 5) Trousers with round side-pleats - With saggy side pleats on them, these trousers had round pleats like a drapery style. This pattern was also considered Hellenistic elements shown in the Parthian costumes. The trousers consisted of the underdrawers and the leggings (called salwar or shalwar), which is thought to emphasize its functionality for its wearer to mount a horse with more ease. 6) Trousers with vertical pleats - With straight vertical pleats on them, these trousers had some volumes and bias decorations in the middle of them. These styles were thought to be worn by the ruling class of the Parthia from early to late period.

• Journal of Astronomy and Space Sciences
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• 제19권4호
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• pp.305-318
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• 2002

한반도 상공의 중간 자외선 대기광을 측정하기 위해 3단형 과학로켓(KSR-III)에 탑재될 대기광도계(Airglow Photometer, AGP)가 제작되었다. 대기광도계 비행 모형(FM)은 4-channel로 이루어져 100km~300km 구간의 중간 자외선 영역의 OI 2972${\AA}$, $N_2$ VK(0,6) 2780${\AA}$, $N_2$ 2PG 3150${\AA}$ 대기광과 배경으로 3070${\AA}$을 지평선 방향으로 측정하게 된다. 대기광도계는 광도계 본체, 차폐경(Baffle), 전자제어부, 전원공급기로 구성되어 있다. 광도계 본체는 협대역 간섭 필터를 통해 선택된 파장의 대기광을 직경 2.5cm 렌즈로 초점면에 설치된 실틈(slit)을 통해 자외선 감지용 광전증배관으로 진입시키는 구조로 되어있다. 비행중 영점 측정을 위해 초점면 실틈 뒤편의 회전판에 영점광원을 설치하였다. 차폐경은 저충대기로부터 산란되는 태양광이 광도계로 진입하지 못하도록 성능을 최적화하여 설계 제작되었다. 대기광도계 비행모형의 지상 테스트로서 각광도계의 성능 테스트 및 감응도, 영점 측정 등을 실시하였다. 대기광도개가 미약한 빛을 감응하도록 제작되었기 때문에 국내에서 신뢰도를 갖고 절대 감응도를 결정할 수 없었다. 그러나 대기광도계 각 channel 간 상대 감응도 측정값은 안정되게 측정되었기 때문에, 추후 로켓 비행시 측정한 자료를 신뢰성있게 분석할 수 있을 것으로 기대된다.