• 대한기계학회논문집B
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• 제25권6호
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• pp.758-765
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• 2001

Purpose of the present is to investigate the food configuration at a tunnel entrance for reducing the micro pressure wave that is generated according to train speed. Two configurations were examined for tunnel of 0.5 km length. The experimental results show that a slit cover hood installed at the entrance of the tunnel reduces the maximum micro pressure wave by 41.2%, and a configuration with a slit cover hood installed at the entrance and a 45$^{\circ}$slanted portal at the exit of the tunnel suppresses it by 47.7%.

• 한국터널지하공간학회 논문집
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• 제2권3호
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• pp.3-11
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• 2000

본 연구의 목적은 고속철도 터널 입구에 슬릿 커버 후드를 적용하여, 고속열차 터널 진입시 터널 출구 쪽에서 방사되는 미기압파를 저감시키는데 있다. 경부고속철도 $107m^2$의 단면적을 갖는 슬라브 궤도 0.5 km 터널에 대하여 슬릿 커버 후드라는 구조물 대책을 마련하였다. 개발시험 결과는 터널 입구에만 후드를 설치했을 경우 미기압파가 최대 41.2 %가 저감되었으며, 터널 입구에 후드를 설치하고 출구에 $45^{\circ}$ 경사갱구를 설치했을 경우는 47.7 %가 저감되었다.

• 설비공학논문집
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• 제8권1호
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• pp.166-175
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• 1996

In recent years, air-conditioning units designed with higher efficiency and more compactness are required due to emphasis on energy efficiency in home electrical appliances. This trend in the air-conditioning industries has accelerated the development of improved heat exchanger with a better performance in heat transfer aspects. In this study, experiments were performed to investigate the shape and configuration of fins affecting on the performance of the conventional fin-and-tube type heat exchanger equipped in a commercial air conditioners. The geometry similtude method was employed to measure the heat transfer coefficient and pressure drop. Experimental results show that this method is very useful to analyze the heat transfer characteristics of the fin-and-tube type heat exchanger. It is also found that the slit fin has better performance than the conventional fin type in the air conditioners. The present results indicate that heat transfer from the fin si influenced by the parameters such as the forming area of the slit fin, the type of interrupted surfaces like a louver or slit, slit patterns and slit raised direction, and it also affects the overall heat exchanger performance.

• 국제초고층학회논문집
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• 제8권3호
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• pp.221-227
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• 2019

In this paper passive seismic retrofit devices for building structures developed by the author in recent years are introduced. The proposed damping devices were developed by slightly modifying the configuration of conventional devices and enhancing their effectiveness. First a seismic retrofit system consisting of a pin-jointed steel frame and rotational friction dampers installed at each corner of the steel frame was developed. Then two types of steel slit dampers were developed; box-type slit damper and multi-slit damper. In addition, hybrid dampers were developed by combining a slit damper and a friction damper connected in parallel. Finally a self-centering system was developed by using preloaded tendons and viscous dampers connected in series. For each retrofit system developed, an appropriate analytical model was developed, and the seismic performance was verified by loading test and earthquake analysis of case study structures. The experimental and analysis results show that the proposed systems can be used efficiently to enhance the seismic performance of building structures.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.619-624
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• 2000

The purpose of present study is to investigate for reducing micro pressure waves generated according to train speeds $(240km/h{\sim}380km/h)$ through tunnels with countermeasures as followings; the hood configuration in tunnel entrance. We developed hoods for tunnel of 0.5 km length in the condition of tunnel cross-section area of $107m^2$ on the slab track. According to the results the maximum micro-pressure wave is reduced by 41.2% for the slit hood installed at the entrance of the tunnel and reduced by 47.7% for the slit hood installed at the entrance of the tunnel and the $45^{\circ}$ slanted portal at the exit of the tunnel

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.576-580
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• 2005

New real-time confocal microscopy using spectral encoding technique and slit confocal aperture is proposed and designed. Spectral encoding technique, which encodes one-dimensional spatial information of a specimen in wavelength, and slit aperture make it possible to obtain two-dimensional lateral image of the specimen simultaneously at standard video rates without expensive scanning units such as polygon mirrors and galvano mirrors. The working principle and the configuration of the system are explained. The variation in axial responses for the simplified model of the system with normalized slit width is numerically analyzed based on the wave optics theory. Slit width that directly affects the depth discrimination of the system is determined by a compromise between axial resolution and signal intensity from the simulation result. On the assumption of the lateral sampling resolution of 50 nm, design variables and governing equations of the system are derived. The system is designed to have the mapping error less than the half pixel size, to be diffraction-limited and to have the maximum illumination efficiency. The designed system has the FOV of $12.8um{\times}9.6um$, the theoretical axial FWHM of 1.1 um and the lateral magnification of-367.8.

• Journal of the Optical Society of Korea
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• 제13권3호
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• pp.330-334
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• 2009

A simple and compact frequency swept laser is demonstrated at $1.3{\mu}m$ using a wavelength scanning filter based on a rotating slit disk. The laser is comprised of a pigtailed semiconductor optical amplifier, a circulator, and a wavelength scanning filter in an extended cavity configuration. The wavelength scanning filter is composed of a collimator, a diffraction grating, a rotating slit disk, and a mirror. The instantaneous laser output power is more than 5 mW. The scanning range of the laser is extended to 80 nm at the maximum level, and 55 nm in the full width at half maximum at a scanning rate of 2 kHz.

• 한국가시화정보학회지
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• 제7권2호
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• pp.28-34
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• 2010

Two turbulent jet with different sinusoidal nozzle exit configurations of in-phase and $180^{\circ}$ out-of-phase were investigated experimentally using a smoke-wire method and a hot-wire anemometry. Mean velocity and turbulence intensity were measured at several downstream locations under $Re_D\;=\;5000$. For the case of in-phase nozzle configuration, the length of potential core exhibits negligible difference with respect to the transverse locations (0, $\lambda/4$ and $\lambda/2$), similar to that of a plane jet. On the other hand, a maximum difference of 30% in the potential-core length occurs for the $180^{\circ}$ out-of-phase configuration. The spatial distributions of turbulence intensities also show significant difference for the nozzle of $180^{\circ}$ out-of-phase, whereas non-symmetric distribution is observed in the near-exit region(x/D = 1) for the in-phase sinusoidal nozzle jet. Compared to a slit planc jet, the sinusoidal nozzle jets seem to suppress the velocity deficit as the flow goes downstream. The sinusoidal nozzle jet was found to decrease turbulent intensity dramatically. The flow visualization results show that the flow characteristics of the sinusoidal nozzle jet are quite different from those of the slit plane jet.

• 한국전자파학회논문지
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• 제17권3호
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• pp.280-286
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• 2006

본 논문에서는 휴대 단말기의 PIFA 내장형 안테나를 설계하기 위한 최적의 급전 위치를 결정하는 방법을 나타내었다. 안테나 방사체와 접지간의 전계 크기가 클수록 방사 전력이 크게 되어 결국 이득이 증가하는 원리를 이용하였다. PIFA 내장형 안테나의 급전 위치는 슬릿 형상 및 캐리어의 물질과 구조 등과 함께 안테나 이득을 결정하는 중요한 요인이다. 본 연구에서는 급전 위치에 따라 전계 강도가 최적 급전 위치 때보다 $2{\sim}10dB$ 감소함을 보였다. Ansoft사의 HFSS 시뮬레이션을 사용하여 삼성 휴대폰에 적용된 2 모델에 대해 시뮬레이션 하였고, 모델별 최적의 급전 위치를 구하였다.

• 한국진공학회지
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• 제16권1호
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• pp.46-51
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• 2007

포항가속기연구소의 HFMX(High Flux Macromolecular X-ray crystallography) 빔라인은 다극 위글러의 방사광을 이용한다. 따라서 고 열량부하에 적합한 두 개의 수평 및 수직 슬릿이 빔라인의 프론트엔드 영역에 설치되었다. 빔 산란을 피하면서 고 열량부하를 처리하기 위하여, 빔을 차단하는 수평 슬릿의 두 글리드콥 블록은 수직면 상에서 기울어진, $10^{\circ}$의 스침각 경사면 구조를 이루고 있다. 글리드콥 블록들은 두 개의 구동막대에 의해서 궤도대를 따라 각각 병진함으로써 슬릿의 간격을 조정한다. 구동막대 내부에 가공된 유로를 통하여 흐르는 냉각수가 두 블록의 열량부하를 냉각시킨다. 수직 슬릿은 진공용기에 대한 설치 방향과 스침각 경사면 구조의 경사각만 다를 뿐 수평 슬릿과 동일한 구조를 가지고 있다. 블록들이 궤도대 상에서 정밀하게 조정되므로 두 블록 간의 정렬이 필요치 않은 장점이 있으며 설치된 슬릿들은 안정적인 작동 성능을 보이고 있다. 또한, 두 슬릿의 냉각 성능도 만족할 만한 것으로 나타났다. 본 논문에서는 두 슬릿의 설계에 대한 상세한 설명이 제시되고 그 작동 성능을 검토한다.