• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.381-384
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• 2005

암반의 단열은 현재까지의 대상암석에 기록된 변형이력의 하나로서, 이는 지하수유동이나 암반의 안정성 해석에 중요한 정보가 된다. 본 연구에서는 대전 유성지역의 암반의 단열 파악을 목적으로, 초음파 텔레뷰어(BHTV) 검층 자료를 선정하여 D/B를 구축하였다. 구축한 D/B를 토대로 시추공의 속성 자료를 3차원 가시화하여 단열분포에 대한 이해를 증진시키고자 하였으며, 3차원 가시화는 GIS의 소프트웨어인 ArcGIS의 AML (ArcMacro Language)을 이용하여 표현하였다. 이러한 연구방법을 통하여 사용자는 암반의 단열 분포를 정확하고, 효과적으로 파악할 수 있을 것이다.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.43.4-44
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• 2009

electron, ion, heavy ion으로 구성 된 plasma에서 hump type과 kink type(double layer)의 electrostatic solitary waves이 존재할 수 있다는 것을 pseudopotential method를 이용한 결과와 1d PIC(Particle-In-Cell) simulation method의 결과에서 각각 확인하였다. 1d PIC simulation에서 초기에 각각의 입자 종(species; electron, ion, heavy ion)의 밀도섭동(density perturbation)은 Gaussian 형태로 주었으며, 각각의 입자들의 drift velocity는 각각의 plasma 입자 종들의 thermal velocity로 나란한 방향으로 주었다.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.137-139
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• 2005

본 논문에서는 30W급 스위칭형 직류전원장치 (Switching Mode Power Supply : SMPS)에 준공진형 프라이 백 스위칭 레귤레이터(quasi-resonant flyback switching regulator)를 적용하여 방사노이즈(radiation-noise)를 억제한 사례에 대하여 설명하고 있다. 기존의 PI사(社)의 TOP IC 시리즈$^{[1]}$와 같이 보편적으로 사용되고 있는 일명, 하드 스위칭(hard-switching)형 레귤레이터를 사용할 경우, 고속 스위칭시에 스위칭 손실(switching loss)과 스위칭 노이즈(switching noise)가 발생한다. 이로 인하여 SMPS의 발열에 따른 효율저화와 방사 노이즈에 의한 전파방해 등이 문제점이 된다. 본 논문에서는 일본의 Sanken사(社)에서 개발/시판중인 준공진형 스위칭 레귤레이터인 STR-F6000 IC 시리즈$^{[2]}$를 이용하여 프라이백 SMPS를 구성하여 방사노이즈를 저감하였다.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.596-600
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• 2008

An experimental study has been conducted on the free convection heat transfer for the 7 kinds of circular finned tube heat exchangers. Empirical correlation was suggested at the range of 3,500$D_o$/$D_i$<3.0, 0.19<$P_f$/$D_i$<0.34. The 92% of experimental data agreed with the correlation within 10%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.207-208
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• 2007

Recently, high performance microelectronic devices are designed in multi-layer structure in order to make dense wiring of metal conductors in compact size. Imprint lithography have received significant attention due to an alternative technology for photolithography on such devices. In this work, we synthesized dielectric composite materials based on epoxy resin, and investigated their thermal stabilities and dynamic mechanical properties for thermal imprint lithography. In order to enhance the mechanical properties and toughness of dielectric material, various modified polyetherimide(PEI) was applied in the resin system. Curing behaviours, thermal stabilities, and dynamic mechanical properties of the dielectric materials cured with various conditions were studied using dynamic differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), and Universal Test Method (INSTRON).

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.11a
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• pp.191-192
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• 2022

본 논문에서는 딥러닝의 주요 기법 중 하나인 GAN 을 활용하여 압축된 영상의 품질을 개선하는 방법을 제안한다. 제안하는 GAN 의 생성자는 U-Net 과 ResNet 을 기반으로 구성되었으며, 판별자는 합성곱층과 전연결층으로 구성하였다. 네트워크의 학습은 HEVC (High Efficiency Video Coding)의 테스트 모델인 HM16.25 를 사용하여 RA (Random Access) 구성하에 양자화 계수 37 로 압축된 영상을 입력으로 하여 수행되었다. 제안하는 네트워크의 성능 확인을 위해 학습 시와 동일한 조건으로 압축된 다른 영상을 입력으로 하여 실험하였다. 실험 결과 영상의 평균 PSNR 은 34.20dB 에서 34.24dB 로 0.04dB 의 품질 향상이 이루어진 것을 확인할 수 있었다.

• Journal of IKEEE
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• v.24 no.1
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• pp.238-242
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• 2020

This paper presents a technique using a multilayered dielectric coating to reduce the radar cross section (RCS) value of an integrated mast mounted in a destroyer. The proposed multilayer structure has the advantage of being easy to fabricate because the dielectric constant is defined so that a general dielectric that does not contain a magnetic component that requires high dielectric constant or is frequently used for blocking electromagnetic wave absorption can be used. After applying the proposed multi-layer dielectric structure to the integrated mast shape, the simulation results show that the RCS reduction performance is 10.9dB at 6GHz, 11.95dB at 12GHz, and 11.63dB at 18GHz compared to the structure without the multilayer structure.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.4
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• pp.112-120
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• 2012

In this paper, we manufactured the wireless video stream system after we scanned EMI(Electro Magnetic Interference)noise in the system. and then, we analysed the noise frequency in the interface, circuit and PCB(Printed Circuit Board). we suggested EMI noise reduction technique. The applied reduction method is low pass filtering, the internal layer placement for high speed video data line and optimization of the system ground condition. the manufactured system improved about 2 ~ 20[dB] margin for EMI limit 40[dBuV/m] at 30 ~ 230[MHz] and 47[dBuV/m] at 230 ~ 1000[MHz].

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.4
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• pp.417-424
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• 2011

Natural convection heat transfer experiments from two parallel horizontal cylinders were performed varying the Pitch-to-Diameter ratio (P/D) of 1.02-9 at Sc of 2,014 to 8,334 and $Ra_D$ of $1.5{\times}10^8$ to $4.5{\times}10^{10}$. Mass transfer experiments that are analogous to the heat transfer experiments were performed using copper electroplating system. In all cases, the measured heat transfer rates for the lower cylinder agreed well with the existing heat transfer correlations developed from a single cylinder. For laminar flows, the measured heat transfer rates of the upper cylinder were less than those of the lower cylinder at P/D less than about 1.5. However, as the P/D increased, the heat transfer rates of the upper cylinder increased. For turbulent flows, the heat transfer rates of the upper cylinder were considerably similar to those of the lower cylinder when the P/D is approximately unity. In contrast, as the P/D increased, the heat transfer rates of the upper cylinder were always higher than those of the lower cylinder.

• Proceedings of the KIEE Conference
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• 1979.08a
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• pp.155-157
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• 1979

The Fourier convolution algorithms are used to reconstruct a 3-D density function from the projection data sets. The convolved data are then back projected to obtain a density function. There are several choices of the weighting function for the design of the reconstruction(deblurring) filter. Present paper reviews the design of reconstruction filter considering the problems such as the effects of sampling rate, aliasing, and noise.