• Journal of the Korean Society for Railway
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• v.15 no.1
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• pp.88-95
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• 2012

Presently, because making process of train service plan consist of various constraint condition, for example structure of track, structure of track in station, train maintenance time and others for considering to be necessary of train management, it has been had extremely complex structure problems. For these reasons, it has big problems to compare analysis for various train service time-table. A study suggest methodology to choice service the most effective schedule and plan of train put before comparative analysis on making train diamond picture's expected effect of established possible various train time-table in making process of train service schedule for improving effectiveness and organization of train service schedule establishment. A study uses Line-Blocking theory for analyzing train service time-table and analyze example for regional train Sadang to Ansan section in 4line.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.161-161
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• 2000

Ferromagnetic 3d 전이금속과 paramagnetic 5d 금속으로 이루어지진 Pt-Co 계는 자기이방적 (magnetic anisotropy) 성질로 인하여 많은 관심을 모으고 있는 계로서는 다층박막 및 합금박막에 대한 지기적 성질에 대한 많은 연구가 있어 왔다. 최근 sputtering method 에 의해 제작된 Pt-Co 합금박막에 대해 Ar 기체분압에 따라 보자력 (coercivity)이 변화되고 PMA (perpendicular magnetic anisotropy)를 갖는 것을 관측하였다. PMA의 근원은 주로 계면에서의 anisotropy 에너지와 관련이 있는 것으로 이해되기 때문에 합금박막의 경우는 PMA가 불가능한 것으로 여겨져 왔다. 그럼으로서 PMA에 대한 근원에 대한 명확한 해석이 필요하게 되었다. 또한 보자력(coercivity)은 불순물의 함량이 감소할수록, 그리고 내부적 변형이 제거될수록 감소하기 때문에, 계면 및 결정구조와 관련이 있는 것으로 알려져 있다. 이러한 자기적 특성을 관찰하고자 [Pt(51 )/Co(112 )]4, [Pt(90 )/Co(66 )]4, 그리고 [Pt(121 )/Co(30 )]4, 다층박막과 이들 박막을 80kV Ar+ 이온선 혼합후 박막의 결정성 변화를 관찰하기 위하여 GXRD (glancing x-ray diffraction) 스펙트럼을 얻어보았다. 그 결과 세 system 모두 disordered fcc 합금박막임을 확인하였다. fcc(111) 방향에 대한 평균 격자공간(lattice spacing)의 크기변화는 한층 당의 Co 두께가 두꺼울수록 거의 선형적으로 감소함을 볼수 있었다. MOKE 실험에 의하면, 이들 다층박막이나 합금박막의 경우 모두, in-plane 방향에 대해 자화 용이축(easy magnetization axis)을 가지고 있었다. 그리고 보자력의 크기에 있어서, 다층 박막의 경우에 있어서 Co 층에 두께 두꺼울수록 보자력의 크기가 감소하였지만 그림1에서와 같이 합금박막의 경우는 정반대로 Co층의 두께가 얇을수록 보자력의 크기가 감소함을 관찰하였다.

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.69-69
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• 2017

Flame arrestor as end of line flame arrester for endurance burning prevents a light-back at deflagration and stabilized burning (during and after endurance burning) of potentially explosive vapor-air and gas-air mixtures at the end of vent pipes. In a flame arrestor, spring is an important part. The spring load as well as the spring's elasticity determine when the hood is opened. In addition, the spring have to work in high temperature condition due to gas burning. Therefore, it is necessary to analyze mechanical load and elasticity of spring when gas is burned. Based on the dynamic calculation on working process of a specific flame arrestor, analysis of spring is taken. A three dimensional model for spring burned in flame arrestor by using CFD simulation. Results of the CFD analysis are input in FEM simulation to analyze structure of the spring. The simulation results can predict and estimate the spring's load and elasticity at variation of the spring's deflection. Moreover, the obtained result can provide makers with references to optimize design of spring as well as flame arrestor.

• Journal of the Korea Society of Computer and Information
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• v.25 no.9
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• pp.63-69
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• 2020

Image-image translation is a technology that creates a target image through input images, and has recently shown high performance in creating a more realistic image by utilizing GAN, which is a non-map learning structure. Therefore, there are various studies on image-to-image translation using GAN. At this point, most image-to-image translations basically target one attribute translation. But the data used and obtainable in real life consist of a variety of features that are hard to explain with one feature. Therefore, if you aim to change multiple attributes that can divide the image creation process by attributes to take advantage of the various attributes, you will be able to play a better role in image-to-image translation. In this paper, we propose Multi CycleGAN, a dual attribute transformation structure, by utilizing CycleGAN, which showed high performance among image-image translation structures using GAN. This structure implements a dual transformation structure in which three domains conduct two-way learning to learn about the two properties of an input domain. Experiments have shown that images through the new structure maintain the properties of the input area and show high performance with the target properties applied. Using this structure, it is possible to create more diverse images in the future, so we can expect to utilize image generation in more diverse areas.

• Fire Science and Engineering
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• v.31 no.1
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• pp.50-57
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• 2017

The present article discusses the response characteristics of smoke detector chamber due to dust and wind velocity. Although situations have improved in terms of early sensing of fires as the smoke detectors are applied indoors, studies tend to place insufficient focus on the side effects and malfunction that can be caused by diversified life dust produced indoors and environmental requirements, etc. Therefore, in the present study, 4 types of photoelectric smoke detectors with different forms and structures of smoke chamber were selected as the experimental objects, and dust test was conducted with fly ash, talcum powder and fiber dust as experiment samples to study indoor applicability of the smoke detectors in terms of their response to diversified dust and wind velocity. Also, to observe response characteristics due to pollution level inside the smoke chamber, wind velocity for dust test were set additionally at 0.25 m/s, 0.5 m/s, and 1.0 m/s. Based to the experimental results, fly ash, talcum powder, and fiber dust (black hair powder) were found to be suitable at the dust test reference wind velocity conditions of 0.25 m/s for both operation test and non-operation test after dust application. On the other hand, under the harsh wind velocity conditions of 0.5 m/s and 1.0 m/s, malfunction of unwanted alarm was observed in non-operation tests in the case of fly ash and talcum powder, and non-operation was confirmed to occur in the case of fiber dust as the alarm failed to operate normally in operation tests.

• Journal of Astronomy and Space Sciences
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• v.13 no.2
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• pp.173-180
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• 1996

This paper briefly describes the KITSAT-1 and KITSAT-2 spacecrafts and presents the functions, calibration procedures and in-orbit results of the KITSAT-2 analog sun sensors have been flown as an experimental payload for the future mission. We have two constraints in their design: small size and very low power consumption due to the tight mass and power budget of the spacecraft. Two one-dimensional analog sun sensors are mounted on the top facet of the KITSAT-2 spaceraft. Each has $\pm$60 degrees of view angle and they cover 210 degree field of view in total as the 30 degree view angles are overlapped. Only the relative sun angle around the Z-axis (yaw-axis) and the spin rate of the spacecraft can be achieved as the one dimensional sun sensors are used and they are aligned with the Z-axis. The calibration formulae are obtained using the fifth order line fitting algorithm for each sun sensor on the ground and they are applied to the obtained in-orbit data. ASS-1 with silicon solar cells has maximum error of 1.5 degree and ASS-2 with silicon photocells manufactured at KAIST has maximum error of 0.5 degree except near 0 degree of sun ray incident anagle where random reflection of incident sun ray is maximum in orbit. The results are presented in chapter 4. The performance of each sun sensor and the possible mounting errors are stated in chapter 5.

• International Area Studies Review
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• v.12 no.3
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• pp.69-88
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• 2008

Firms or internal exchanges exist to eliminate or at least reduce transaction costs from the separating process in many firms by dealing more efficiently with bounded rationality, complexity, and tendency towards opportunism faced by the markets so that vertical integration is supposed to have a positive relationship with performance. The organizational structure of Korean economy in the latter part of the $20^{th}$ century is much related with this transaction costs' view. I propose to estimate the effect of vertical integration on the firm's performance using the data of the Korean listed corporations from 1991 to 1995, therefore. The estimated results show that vertical integration at firm level is negatively and significantly related with the firm's performance: the higher level of vertical integration the worse performance. However, the group level integration is not related with performance at all.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.212-216
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• 1999

SiC(3C) photodiodes (PDs) were fabricated on p-type Si(111) substrates using chemical vapor deposition (CVD) technique by pyrolyzing tetramethylsilane (TMS) with $H_{2}$ carrier gas. Electrical properties of SiC(3C) were investigated by Hall measurement and current-voltage (I-V) characteristics. SiC(3C) layers exhibited n-type conductivity. Ohmic contact was formed by thermal evaporation Al metal through a shadow-mask. The optical gain $(G_{op})$ of the SiC(3C)/Si PD was measured as a function of the incident wavelength. For the analysis of the photovoltaic detection of the Sic(3C) n/p PD, the spectral response (SR) has calculated by using the electrical parameters of the SiC(3C) layer and the geometric structure of the PD. The peak response calculated for properly chosen parameters was about 0.75 near 550 nm. We expect a good photoresponse in the SiC(3C) heterostructure for the wavelength range of 400~600 nm. The SiC(3C) photodiode can detect blue and near ultraviolet (UV) radiation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.10
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• pp.996-1003
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• 2003

There are critical drawbacks in fabricating MMIC transversal filters because the length of the conventional transversal filter structure is much longer than the width. In order to solve this structural problem, a transversal filter using multiple-coupled-line directional couplers which can achieve tight coupling is proposed. The length of the proposed transversal filter can be made short using multiple-coupled-line couplers so that the structure of the proposed filter is applicable to MMIC technology. Because of the dielectric and conductor losses, the excited signal at the input port becomes smaller when it progresses through each directional coupler. Therefore, the strength of the coupled signals at the latter directional couplers becomes smaller than the designed one and this, in turn, gives rise to performance aggravation. A modified coupling coefficient formula to prevent frequency characteristic degradation is introduced. The proposed filter structure and the design method are verified by the calculated result and 3D full-wave analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.988-996
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• 1998

BN ceramics with 0.07wt% $V_{2}O_{5}$ and 0.03wt% CuO(BNC3V7) sintered at $900^{\circ}C$ where it is possible for these to be co-fired with Ag electrode. Dielectricconstant of 44.3, TCF of 22 ppm$/^{\circ}C$ and $Qxf_{o}$ value of 22,000 GHz can be obtained from BNC3V7, multilayer type band pass filters using tapped method and conventional method were designed for PCS (Personal Communication System) applications. Tapped method by adopting input/output-tapping scheme the chip filter stucture becomes simpler and needs fewer layers than that using the conventional input/output-coupling scheme. A multilayer type band pass filter fabricated by screen-printing with silver electrode after tape casting. The simulated characteristics of the fabricated filters sintered at $900^{\circ}C$ were compared with the designed ones. Even though the centered frequencies of tapped and conventional band pass chaip filters were measured to shift about 90MHz downward, the band pass characteristics of both filters were similar that of designed ones. The spuriousresonance characteristic of tapped pass chip filter was better than that of conventional chip filer.