• Journal of the Korean Regional Science Association
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• v.36 no.4
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• pp.57-67
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• 2020

This study aims to analyze influential factors of residents' housing instability in Korean large cities. The previous studies deal with low-income households' experiences with housing instability. However, this study empirically analyzed the impact of regional characteristics such as spatial openness and community characteristics on residents' housing instability. For this purpose, I analyzed various experiences as symptoms of residents' housing instability using data from the Ministry of Land, Infrastructure, and Transport's (MOLIT) Korean Housing survey through a multi-level logistic regression model. The study finds that regional factors as well as household characteristics influence their housing instability. This result implies that promoting spatial inclusivity alleviate residents' housing instability in metropolitan environments. In addition, this study calls for policy efforts such as a continuous supply of public rental housing and a greater variety of housing types to mitigate housing instability.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.2
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• pp.117-129
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• 2009

Several researches have been done to estimate the earth pressure on a vertical circular shaft considering three dimensional arching effect and verified them by conducting model tests. However, any equation suggested so far is not applicable in case of multi-layered soils and/or C-${\phi}$ soils. In this study, new equation for estimating the earth pressure acting on the vertical shaft in c-${\phi}$ soils is proposed. A parametric study is performed to investigate the significance of the cohesion when estimating the coefficient of earth pressure in C-${\phi}$ soils and estimating earth pressures in vertical shafts. A method which can estimate the earth pressure on vertical shafts in layered soils is also proposed by assuming a failure surface in layered soils and using the modified equation. This paper is Part I of companion papers focusing on the theoretical aspect of model developments; the experimental verification will be made in Part II.

• Journal of radiological science and technology
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• v.33 no.3
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• pp.179-184
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• 2010

A hard X-ray microscope system for obtaining images of nano-spatial resolution has been widely studied and requires monochromatic X-ray. A multilayer mirror of 84% reflectivity was designed to acquire tungsten characteristic X-ray of 8.4 keV from the white beam generated from an X-ray tube, and the C/W multilayer mirror of $50{\times}50\;mm$ size and 5.65 nm d-spacing was fabricated by the ion-beam sputtering system. The C/W multilayer had a uniformity of 99.5%, and the structure of the multilayer mirror was verified by a TEM image. The obtainable x-ray reflectivity for the C/W multilayer mirror at 8.4 keV was estimated from measuring the X-ray reflectivity using the copper characteristic X-ray of 8.05 keV. Monochromatic X-ray of 8.4 keV was generated by combining a X-ray tube, and the reflectivity and monochromaticity were 77.1% and 0.21 keV, respectively. Monochromatic X-ray generated from the combination of an X-ray tube and an C/W multilayer mirror has enough potential to use X-ray source for hard X-ray microscope system of laboratory size. If the C/W multilayer mirror of d-spacing of a few nanometers can be fabricated, monochromatic X-ray corresponded to 17.5 keV, molybdenum characteristic X-ray, can be obtained and applied to mammography in the medical application.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.883-887
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• 2004

현재 전국적으로 $\blacktriangle$ 전기, 가스, 상수도, 하수도, 열수송관 등을 공동 수용하는 '지하공동구'가 14개 도시 30개소에 160.4km $\blacktriangle$ 보행공간으로 병용되는 '지하도로'가 23개도시 118개소에 63만 $m^2$ $\blacktriangle$ 지하도로내 설치된 지하점포가 1만1천798개소 23만$m^2$이 있다. 이와 같이 현대 도시내에서 지상공간의 과밀도 개발로 인하여 지하공간의 수요가 증대되어 지하공간 구조물이 많이 설치되고 있는 반면, 지하상가, 지하천 등과 같은 지하공간 시설에서 발생할 수 있는 침수피해 대책이 미흡한 실정이다. 본 연구에서는 과거 지하공간의 침수피해 실태를 조사하고 그 사례에서 원인을 분석하여 기술적 해결책을 도출해 내며, 침수방지를 위한 대책으로 국내에서 사용하고 있는 기숙이나 국외(미국, 일본)의 침수방지 기술 및 대책, 침수시 가이드라인 등을 조사하였다. 또한 지하공간이 침수되었을 때 일어날 수 있는 위험성에 대하여 이론적인, 기술적인 조건에 대하여 조사하였다. 이를 토대로 지하공간의 유형 즉, 지하주택, 지하상가, 지하공공시설(지하차도, 지하철, 전철, 지하변전소)에 대한 구체적인 침수방지 기숙에 대한 기준을 제시함으로써 궁극적으로는 지방자치단체, 관련기관, 연구기관에서 지하공간 침수방지대책에 대한 기초자료로 활용할 수 있을 것으로 판단된다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.231-236
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• 2017

The space harmonics generated by a plane-wave incident upon a multi-layered dielectric grating can undergo strong resonance scattering variations known as GMR(guided-mode resonance). To clarify these effects, we examine the field propagation and dispersion curve inside the grating region by using a rigorous equivalent transmission-line theory(RETT). The results show that, at the peak of a scattering resonance, the reflected mode is almost identical to a leaky wave that can be supported by the grating structure. Thus, we confirm and generalize previous research that has occurred GMR effect associated with the free-resonant character of leaky waves at multi-layered dielectric gratings. Quantitative simulation results illustrating the behavior of typical gratings are given, and the special case of normal incidence is discussed for TM mode.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.746-752
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• 2005

본 논문에서는 다층 퍼셉트론 신경망 학습을 위한 새로운 두 단계 학습방법을 제안하고 이를 옵션 가격결정 모형에 응용하였다. 제안된 신경망 학습 알고리즘의 첫번째 단계는 Levenberg-Marquardt 알고리즘을 이용하여 빠르게 국소최적해를 찾는 것이고 두 번째 단계는 첫 번째 단계에서 찾은 국소최적해가 원하는 수준에 미치지 못할 경우 선형탐색 터널링을 이용해서 더 나은 해를 찾는 것이다. 이 두 단계를 반복적으로 수행함으로써 연결가중치 공간에서 구하고자 하는 해를 빠르고 안정적으로 찾을 수 있다. 현재 옵션가격결정 모형으로 많이 이용되고 있는 Black-Scholes 모형의 문제점을 극복하기 위해서 제안된 신경망 모형을 옵션가격결정 문제에 사용하였다. 이 모형을 KOSPI200 옵션 데이터로 실험한 결과 Black-Scholes 모형에 비해 검증오차를 60% 가량 줄일 수 있었다.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.155-158
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• 2007

현대사회의 발전으로 인해 생성되는 수많은 정보는 시간과 공간의 제약이 없는 다차원적인 특성을 갖고 있으며, 사회 전반에 걸쳐 보다 나은 결과를 위한 의사결정에 활용되고 있다. 또한 우리생활에서 발생하는 많은 현상을 보다 합리적이고 과학적인 방법으로 분석하여 정확한 예측이 이루어진다면 미래의 불확실성에 대한 불안을 해소하고, 현재의 의사 결정을 하는데 큰 도움이 될 수 있다. 따라서 본 논문에서는 다층 신경망을 이용하여 비선형적 관계를 표현할 수 있는 적응 능력을 갖을 뿐만 아니라 비선형 통계예측에 적용이 가능한 알고리즘을 제안하고 분석하였다.

• Tunnel and Underground Space
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• v.10 no.4
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• pp.506-515
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• 2000

A lot of underground construction projects have been conducted by economical, social and military purposes in Korea for the last three decades. As a result, magnificent amount of data were obtained from geological site investigations, laboratory and field tests, design and field monitoring. But up to now, these valuable informations were neither systematically stored nor utilized efficiently resulting in a great loss of time and money. In this study, a database system named GeoINFO was developed using Microsoft Access 97 for management of informations which can be obtained from underground construction. The developed database system is especially designed to cover three major types of underground facilities-tunnels, underground storages and rock slopes and has multi-layered tree structures for data input. The system also has a unique indexing system for efficient data search using Visual Basic code.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10c
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• pp.354-356
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• 1998

축약 분산 기억 장치는 적응적 문제 해결 능력과 하드웨어화의 용이성으로 인해 현실성이 있는 신경망의 한 모델로 주목받고 있다. 그러나 다층 인식자의 개별 뉴론이 선형의 결정 함수로 해 공간을 이분하고 그들이 다양하게 결합하므로써 일반적인 문제 해결 능력을 갖는데 비해, 축약 분산 기억 장치의 뉴론은 해 공간에서 자신을 중심으로 한 일정 반경 영역을 안과 밖으로 이분하고 이들을 단순하게 합하므로 해 공간이 크기 관계를 갖는 경우 비효율적인 모델로 된다. 본 논문에서는 이러한 축약 분산 기억 장치의 특성과 그 원인을 규명하고 해결 방안으로써 개선된 축약 분산 기억 장치를 제안한다. 아울러 새로운 모델의 적용 예를 ATM 호 수락 제어 과정을 통해 보인다.

• Journal of the Economic Geographical Society of Korea
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• v.24 no.4
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• pp.367-385
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• 2021

This study examined changes in the energy landscape, focusing on the photovoltaic module carbon certification system. As the global photovoltaic market has been reorganized around Chinese companies, the South Korean government has pushed to strengthen the competitiveness of the nation's photovoltaic industry. However, a limitation remains in that the government-led effort was not sufficient to bring about dynamic changes in the energy landscape. Against this backdrop, this study explored the stages leading to the multi-level perspectives of "macro-environment, socio-technical regime, and niche" to track the process of the government and domestic photovoltaic companies as part of a socio-technical regime responding to global market changes. In particular, this study raised an issue with the conceptual discussion of multi-level perspective, which placed a particular emphasis on the rate of change at each level and the niche in which innovative experiments take place, and thus attempted to fill this gap by tracking the energy landscape that varies differently from space. These spatial discussions can track different carbon emissions coefficients and industrial characteristics for each country, and have a higher level of explanatory power for the system thus constructed. In addition, through discussions on the problems and implications of the government-led introduction of renewable energy policies, this study suggests the need to create and implement a field-oriented system.