• 한국위성정보통신학회논문지
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• 제11권1호
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• pp.1-5
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• 2016

본 논문에서는 L-Band 대역의 항행안전시설(DME, TACAN)에 적용 가능한 광대역 High power pulsed amplifier를 구현하였다. L-Band 대역의 항행안전시설의 특성상 구현된 SSPA는 매우 높은 출력과 선형성, 효율 특성을 요구한다. 이에 본 논문에서는 변형된 class F 기법을 이용하여 효율 특성을 개선하였다. 또한 hybrid coupler를 이용한 Balance 구조와 구동부 증폭단의 비선형 특성을 이용한 anti-phase 기법, 출력부 harmonic trap 등을 이용하여 선형 특성을 개선하였다. 구현된 SSPA는 약 300MHz의 대역폭을 가지며, 1.5KW 출력과 55%의 효율 특성을 보였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1223-1228
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• 2007

Since KHSL 2nd phase was adapted as a main track design, the interests of concrete slab track system have been gradually increased in the division of rail track engineering and many engineering companies have been trying to adapt a concrete slab track system at this moment. Advantages of this system proved in advanced country, japan and Germany etc. are excellent maintenance, track stability and increasing of buckling resistance This developed turnout is same with the KHSR 1st phase's design and applications rules, components and signaling system since it observes KTX specification. Comparing it with the former turnout, High-elasticity pad, lubrication-free roller slide plate and Rheda2000 PC sleeper are only different. The purpose of this study is the development of high speed turnout on concrete slab track and its application on site. Now these studies are going to show the verification and confidence about the interface between ballast-track and concrete slab track by finding and solving the possible problems when it is installed on site and to make these turnouts applied perfectly and completely on concrete slab track. Its first trial construction in korea had been successfully completed at Sangju-station on July 20th ,2007 thanks to KORAIL and KR. Hereunder Sampyo E&C trys to introduce all of turnout technologies on concrete slab track system with Rheda 2000 sleeper

• 복식문화연구
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• 제15권4호
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• pp.713-725
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• 2007

This treatise is designed to discover the principle of timeless continuity of Korean design from the perspective of modem accomodation of formative beauty of tractional dress style with the focus on measurement analysis of dress from visual perspective. For this purpose in this research the following subjects are studied with concentration: the 1st phase debate on the dress style appearing in the Kokuryo murals and genre painting during the later period of Chosun Dynasty regarding the formative beauty of dress style. 2nd phase debate on the points of changes and transformations during given age and given principle of Korean designs being maintained across the span of time in the context of madern accomodation of such traditional dress. From historical perspective characteristics of each given age and principles of visual formative principles appear in various ways variety attributable to mutually interactive principles according to historical background and culture. For this reason it can be said that they are determined by different paradigm or forms from characteristics of Korean style design in the present and future and those for traditional forms of dress in the past.

• KSBB Journal
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• 제8권5호
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• pp.438-445
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• 1993

유기칠 폐기물을 보다 효율적으로 처리하고자, 상 분리 혐기발효와 Chiorella 배양에 의한 생우분의 4 단계-복합처리를 시도하였다. 3배 희석 생우분을 6 일간 산발효시킨 발효액을 4 일의 수리학적 체류시 간으로 1차 에탄발효조에 공급했을 때, 평균 977ml/l C비ture/day의 바이오가스가 생산되었고, 1차 발효 폐액을 역시 4일의 체류시간으로 2차 메탄발효조에 공급했을 때 평균 428ml/l culture/day의 바이오 가스가 생산되었다. 1차 메탄발효의 바이오가스 생 산성은 재래의 단일조식과 비교했을 때 31.4% 증가 되었다. 또한 산발효과정, 1차 및 2차 에탄발효과정 의 유기물 제거율은 각기 71.8%, 42.6% 그리고 2 24.0%였다. 한편, 2차 메탄발효폐액은 Chiarella s sp. PSH3에 의해 10일의 체류시간으로 반연속배양 처리한 결과, 평균 1.8g/l culture/day(2.8$\times$106 cells/ml)의 조체가 생산되었고, 이 과정의 유기물 제거율은 73%였다. 이상의 4단계 처리과정을 통하 여 초발원료인 3배 희석 생우분의 COD가 51, 300ppm에서 최종단계인 Chiarella의 처리에 의해 평균 85ppm으로 감소되어 총유기물 제거율이 99.8 %에 달하였다. 이들의 결과는 유기질 폐기물의 효 율적 처리와 더불어 바이오가스와 균체단백질을 생산하는 복합처리계의 구성이 가능함을 나타낸다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제3권2호
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• pp.89-95
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• 2003

In this paper, we have designed and fabricated high conversion gain Q-band active sub-harmonic mixers for a receiver of millimeter wave wireless communication systems. The fabricated active sub-harmonic mixer uses 2nd harmonic signals of a low local oscillator (LO) frequency. The fabricated mixer was successfully integrated by using $0.1{\;}\mu\textrm{m}$GaAs pseudomorphic high electron mobility transistors (PHEMTs) and coplanar waveguide (CPW) structures. From the measurement, it shows that maximum conversion gain of 4.8 dB has obtained at a RF frequency of 40 GHz for 10 dBm LO power of 17.5 GHz. Conversion gain from the fabricated sub-harmonic mixer is one of the best reported thus far. And a phase noise of the 2nd harmonic was obtained -90.23 dBc/Hz at 100 kHz offset. The active sub-harmonic mixer also ensure a high degree of isolations, which are -35.8 dB from LO-to-IF and -40.5 dB from LO-to-RF, respectively, at a LO frequency of 17.5 GHz.

• 한국실내디자인학회논문집
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• 제18권6호
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• pp.184-193
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• 2009

In recent years, the architectural interest in the apartment design has been getting focused on qualitative improvement and design differentiation. Especially the facade design differentiation is one of the most important elements in this matter. The purpose of this study is to provide the basic informations that can be referenced when architects are dealing with exterior design by analyzed design types and characteristics of apartment entrances. Target apartment of this study was whasung dongtan the 2nd phase new city districts which was planned to solve a housing shortage in the capital region. Having examined eleven pilot districts, four 1st construction areas, and eight 2nd construction areas, - total 23 complexes - 282 apartment entrances in 212 apartment buildings were carefully researched. Apartment entrance design can be divided into 15 different design elements: design types and combination types, direction, shape, height, approach types, exterior wall finishes of entrance, exterior wall finishes of lower parts of apartment, handrail types of slope, floor finishes of slope, distribution ratio of piloti, ceiling height of piloti, floor finishes of piloti, space use of piloti, window establishment between piloti and elevator hall, landscape elements of piloti. Design characteristics of building entrances were also analyzed in 4 groups (I, II, III, IV) divided by construction contractors ranking. In conclusion, first, design types and combination types can be classified into 15 different kinds, and the group I and II tend to show wider variety of entrance combinations. Secondly, the height and volume of extrude entrance type tend to increase in the group I and II. Third, the spatial configuration of pilotis appears to show more of 'pass + store + break' rather than 'access', as we get closer to the group I.

• Wind and Structures
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• 제26권5호
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• pp.267-277
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• 2018

Numerical simulations are performed of a long flexible cylinder undergoing vortex-induced vibration at a Reynolds number of 500. The cylinder is pinned at both ends, having an aspect ratio of 100 (cylinder length to cylinder diameter) and a mass ratio of 4.2 (structural mass to displaced fluid mass). Temporal and spatial information on the cross-flow (CF) and in-line (IL) vibrations is extracted. High modal vibrations up to the $6^{th}$ in the CF direction and the $11^{th}$ in the IL direction are observed. Both the CF and IL vibrations feature a multi-mode mixed pattern. Mode competition is observed. The $2^{nd}$ mode with a low frequency dominates the IL vibration and its existence is attributed to a wave group propagating back and forth along the span. Distributions of fluid force coefficients are correlated to those of the CF and IL vibrations along the span. Histograms of the x'-y motion phase difference are evaluated from the total simulation time and a complete vibration cycle representing the standing or travelling wave pattern. Correlations between the phase difference and the vibrations are discussed. Vortex structures behind the cylinder show an interwoven near-wake pattern when the standing wave pattern dominates, but an oblique near-wake pattern when the travelling wave pattern prevails.

• Journal of Welding and Joining
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• 제28권4호
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• pp.18-25
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• 2010

Super-duplex stainless steels (SDSS) have a good balance of mechanical property and corrosion resistance when they consist of approximately equal amount of austenite and ferrite. The SDSS needs to avoid the detrimental phases such as sigma(${\sigma}$), chi(${\chi}$), secondary austenite(${\gamma}2$), chromium carbide & nitride and to maintain the ratio of ferrite & austenite phase as well known. However, the effects of the subsequent weld thermal cycle were seldom experimentally studied on the micro-structural variation of weldment & pitting corrosion property. Therefore, the present study investigated the effect of the subsequent thermal cycle on the change of weld microstructure and pitting corrosion property at $40^{\circ}C$. The thermal history of root side was measured experimentally and the change of microstructure of weld root & the weight loss by pitting corrosion test were observed as a function of the thermal cycle of each weld layer. The ferrite contents of root weld were reduced with the subsequent weld thermal cycles. The pitting corrosion was occurred in the weld root region in case of the all pitted specimen & in the middle weld layer in some cases. And the weight loss by pitting corrosion was increased in proportional to the time exposed at high temperature of the root weld and also by the decrease of ferrite content. The subsequent weld thermal cycles destroy the phase balance of ferrite & austenite at the root weld. Conclusively, It is thought that as the more subsequent welds were added, the more the phase balance of ferrite & austenite was deviated from equality, therefore the pitting corrosion property was deteriorated by galvanic effect of the two phases and the increase of 2nd phases & grain boundary energy.

• 한국화재소방학회논문지
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• 제33권4호
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• pp.97-104
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• 2019

한국 경제의 초석인 화학산업의 성장 이면에는 매년 수십여 건의 위험·유해화학물질 화학사고로 막대한 인명 및 환경피해가 발생하고 있다. 화학사고 주요 원인으로 염산, 불산 등과 같은 위험·유해화학물질 취급시설에서 작업자의 부주의, 취급시설의 노후화 등으로 방유벽 내 유·누출 후 대기 확산에 의한 인명 및 환경피해가 발생된 사례를 쉽지 않게 접할 수 있다. 이와 같은 화학사고를 예방하기 위해서 방유벽 내 유입된 위험·유해화학물질의 대기 확산 방지를 위한 방재시스템의 필요성이 제기되어 동일 주제에 대해서 연구하였다. 대기 확산 방지를 위한 방재시스템은 유·누출 감지단계, 경보·측정단계, 억제·차단단계 등 총 4단계로 구성된다. 본 연구에서 제안한 위험·유해화학물질방재시스템을 통해서 대기 확산과 같은 2차 화학사고 예방 체계의 필요성을 제기할 수 있다.

• 대한한방부인과학회지
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• 제18권4호
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• pp.219-229
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• 2005

Objective : This clinical study investigated the effect of Yeosindan on dystocia caused by abnormal expulsive forces. Methods : Yeosindan was applied on the umbilicus of a primipara who had gone through latent phase for 15hrs and was almost expected to undergo C-sec by dystocia. It was sealed with an plaster. Yeosindan was removed immediately after the delivery. Results : 1. 90 minutes after Yeosindan had been applied on the umbilicus of the primipara, the active phase dilatation of uterus was started normally. 2. After 190 minutes from the Yeosindan application, the 2nd stage of labor was finished. 3. In this case, the delivery time, of which average is 344 minutes from the active phase to the second stage of labor, was reduced by 244 minutes. 4. So far, no abnormal condition has been detected in both the neonates and the primiparas.