• Tunnel and Underground Space
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• v.25 no.2
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• pp.115-124
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• 2015

Thermal energy storage (TES) is a technology that stores surplus thermal energy at high or low temperatures for later use when the customer needs it, not just when it is available. TES systems can help balance energy demand and supply and thus improve the overall efficiency of energy systems. Furthermore, the conversion and storage of intermittent renewable resources in the form of thermal energy can help increase the share of renewable resources in the energy mix which refers to the distribution of energy consumption from different sources, and to achieve this, it is essential to combine renewable resources with TES systems. Underground TES using rock caverns, known as cavern thermal energy storage (CTES), is a viable option for large-scale, long-term TES utilization although its applications are limited because of the high construction costs. Furthermore, the heat loss in CTES can significantly be reduced due to the heating of the surrounding rock occurred during long-term TES, which is a distinctive advantage over aboveground TES, in which the heat loss to the surroundings is significantly influenced by climate conditions. In this paper, we introduced important factors that should be considered in the shape and multiple layout design of TES caverns, and proposed guidelines for storage space design.

• Journal of Korea Spatial Information System Society
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• v.12 no.1
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• pp.10-17
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• 2010

Sensor nodes used in Geosensor network are resource limited and power constrained. So it is necessary to research on routing protocols to gather data by using energy efficiently. Wireless sensor networks collect data gathered from sensor nodes by transfering it to the sink using multihop. However, it has two problems. First, the existing works require unnecessary data transmission for choosing a proper parent node to transfer data. Secondly, they have a large number of data transmission because each sensor node has a different path. To solves the problems, we, in this paper, propose a designated path based data aggregation scheme for efficient energy management in WSNs. The proposed scheme can reduce unnecessary data transmission by pre-determining a set of paths and can enable all the sensor nodes to participate in gathering data by running them in round-robin fashion. We show from performance analysis that the proposed scheme is more energy efficient than the existing directed diffusion(DD) and the hierarchical data aggregation(HDA).

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.104.2-104.2
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• 2012

미국, 중국, 일본, 인도 등과 같은 세계 여러 국가들이 달 및 화성 탐사를 수행하고 있는 현시점에서 우리나라도 2025년에 달 탐사를 계획하고 있다. 인간에게 있어서 우주공간은 고에너지 환경의 영향을 많이 받는 곳이다. 향후 달, 화성과 같은 다른 행성으로의 이주를 생각하고 있는 현 시점에서 우리는 고에너지우주방사선 환경의 영향을 고려해야 한다. 지구에서의 인간은 지구 자기장과 대기에 의해 고에너지 우주선 환경으로부터의 영향을 덜 받는다. 그러나 달과 화성의 경우는 다르다. 달의 대기는 거의 없고 자기장도 무시할 정도로 매우 작으며, 화성 또한 자기장이 거의 없으며 대기 또한 얇아서 Galactic Cosmic Ray (GCR)나 Solar Energetic Proton (SEP) 등으로부터 인간은 많은 영향을 받을 수 있다. 이러한 위험으로부터 인간이 보호받을 수 있는 곳은 달과 화성의 지표 아래나 동굴이라고 볼 수 있다. 그래서 달 및 화성의 표면과 지하 영역에 대한 고에너지 우주선 환경의 깊이에 따른 영향을 분석하여 어느 정도로 두터운 천장을 가진 동굴이어야 우주인들이 상주하는 지하공간을 지구표면에서의 방사선 환경과 같은 수준으로 유지할 수 있는지를 추정해 보려고 한다. 달 표면 토양의 화학적 구성성분은 Maria와 Highlands로 구분되어 약간의 차이가 있다. 달의 Maria 토양은 $SiO_2$ - 45.4%, $Al_2O_3$ - 14.9%, CaO - 11.8%, FeO - 14.1%, MgO - 9.2%, $TiO_2$ - 3.9%, $Na_2O$ - 0.6%이고 Highlands의 토양은 $SiO_2$ - 45.5%, $Al_2O_3$ - 24.0%, CaO - 15.9%, FeO - 5.9%, MgO - 7.5%, $TiO_2$ - 0.6%, $Na_2O$ - 0.6%의 화학적인 구성비를 가진다. 또한 화성표면은 $SiO_2$ - 43.9%, $Al_2O_3$ - 8.1%, CaO - 6.0%, FeO - 18.1%, MgO - 7.1%, $Na_2O$ - 1.4%의 토양의 화학적인 구성비를 가지고 있다. 본 연구에서는 이러한 구성비를 가지고 있는 달과 화성 표면에 대한 우주방사선의 영향을 분석하기 위해서 GEANT4를 사용하여 수행한 전산 모사의 결과를 발표할 것이다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.3
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• pp.179-188
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• 2015

This study reviewed the type of the project and developmental plan related to ocean energy development in the coastal land boundaries and the ocean, and suggested the efficient scoping method through the diagnosis of the key items of environmental impact assessment (EIA) in the coastal area. The major projects are the construction of tidal power plant, tidal current power plant, and offshore wind power plant in the public water, and also those are the construction of solar power plants in the coastal land boundaries. While the project plans on a large scale such as the construction of tidal power plant, it is important to consider both property of usefulness of the designated areas and harmony analysis with marine space availability based on the adequacy of the site selection and relevance of plan with the master plan for reclamation and strategic environmental assessment (SEA). And also it needs to be considered the careful checkup on the EIA checklist referring to the type of project, effective post-monitoring, and suggestion of mitigating methods to minimize the environmental impacts during the stage of actual environmental impact assessment. Introduction of a system of integrated marine environmental impact assessment should be considered for reasonable and effective manage to developmental projects on the marine spatial area.

• The Journal of the Korea Contents Association
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• v.4 no.1
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• pp.18-23
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• 2004

In this paper, we propose a new visual feature extraction method for content-based image retrieval(CBIR) based on wavelet transform which has both spatial-frequency characteristic and multi-resolution characteristic. We extract visual features for each frequency band in wavelet transformation and use them to CBIR. The lowest frequency band involves spacial information of original image. We extract L feature vectors using fuzzy homogeneity in the wavelet domain, which consider both the wavelet coefficients and the spacial information of each coefficient. Also, we extract 3 feature vectors wing the energy values of high frequency bands, and store those to image database. As a query, we retrieve the most similar image from image database according to the 10 largest homograms(normalized fuzzy homogeneity vectors) and 3 energy values. Simulation results show that the proposed method has good accuracy in image retrieval using 90 texture images.

• The Journal of the Acoustical Society of Korea
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• v.10 no.4
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• pp.27-37
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• 1991

This paper proposes the ESFVQ(energy subspace fuzzy vector quantization) that employs energy subspaces to reduce the quantizing distortion which is less than that of a fuzzy vector quatization. The ESFVQ is applied to a speaker adaptation method by which Korean words spoken by unknown speakers are recognized. By generating mapped codebooks with fuzzy histogram according to each energy subspace in the training procedure and by decoding a spoken word through the ESFVQ in the recognition proecedure, we attempt to improve the recognition rate. The performance of the ESFVQ is evaluated by measuring the quantizing distortion and the speaker adaptive recognition rate for DDD telephone area names uttered by 2 males and 1 female. The quatizing distortion of the ESFVQ is reduced by 22% than that of a vector quantization and by 5% than that of a fuzzy vector quantization, and the speaker adaptive recognition rate of the ESFVQ is increased by 26% than that without a speaker adaptation and by 11% than that of a vector quantization.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.648-652
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• 2011

Passive autocatalytic recombiner (PAR) is considered as an explosive gas control system in operating NPP plants. This work investigates and evaluates hydrogen recombination performance over manufactured $Pt/TiO_2$ catalysts. When the space velocity increases, the hydrogen conversion decreased, while hydrogen depletion rate (g/sec) increases highly in $35000{\sim}100000hr^{-1}$ Gas Hourly Space Velocity (GHSV). Hydrogen conversion and depletion rate with Pt loading is investigated. As a result, there were no differences in the hydrogen conversion, but exothermic heating rate (K/sec) is increases as Pt loading increases. The catalyst showes a high hydrogen conversion efficiency of 80% under atmospheric conditions.

• Journal of Korean Society on Water Environment
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• v.38 no.2
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• pp.72-81
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• 2022

Numerous studies have investigated the occurrence and fate of microplastics in the environment; however, only limited effort has been devoted to exploring the characteristics of dissolved organic matter (DOM) leached from microplastics. In microplastic (MP)-contaminated environment, MPs are typically mixed with naturally-occurring particles, which interferes with their detection in the environment. Thus, it is necessary to distinguish between the DOM leached from MPs and those leached from natural particles and also to characterize their properties. This study investigated DOM leaching behavior from MPs (polystyrene: PS, polyvinylchloride: PVC) and natural particulates (forest soil: FS, litter leaves: LL) under light, which is considered one of the main weathering processes that affect MPs in the environment. The leached DOM concentrations and fluorescence characteristics were compared under dark versus light conditions. Regardless of the origins, UV light promoted DOM release from all the particulates. More DOM was released from natural particles than from MPs under both conditions. However, the effect of promoting DOM release by UV was more pronounced for MPs than for natural particles. It was observed from fluorescence spectra that the intensity of the humic-like region was substantially reduced when MP-derived DOM was exposed to UV light, whereas the change of intensity was very little for natural particles. Under light conditions, the ratio of protein-like to humic-like fluorescence of MP-derived DOM was higher than that of DOM from natural particles. This study implies that a substantial amount of DOM could be leached from MPs even in MP-polluted environment under UV irradiation. Protein/humic fluorescence ratio could be utilized as a fast probing indicator to separate the two sources of particles under light.

• Land and Housing Review
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• v.14 no.3
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• pp.77-92
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• 2023

The aim of the study is to analyze urban characteristics that affect carbon emissions of buildings. The analysis was conducted at the level of 424 administrative districts in Seoul. The main variables used in the analysis were energy consumption and carbon emissions of buildings published in the Seoul Metropolitan Government's energy information platform 2021. It was found that carbon emissions per unit building were high in Jongno, Gangnam, Guro, and Mok-dong. A regression analysis using the spatial lag model (SLM) identifies that the variables that affect the carbon emissions of buildings were; commercial, educational, business and industrial facility variables as built environment factor; number of residents; traffic volume, number of bus routes and number of subway stations as transportation facilities factors; and environmental factors such as green area and river area.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.496-499
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• 2009

본 논문은 기하학적 비선형성을 가진 보존적 단일 하중 매개변수의 탄성 상태 공간구조의 분기이론에 관한 수치 해석적 기본 방법 및 경로 추적, pin-pointing, 경로 전환을 기술하고 있다. 비선형 탄성 불안정 상태는 극한점과 분기점으로 분류될 수 있으며, 평형경로상의 평형점의 계산 및 평형경로상의 특이점을 찾기 위한 pin-pointing 반복계산을 수행하는 일반적인 비선형 수치해석법으로 극한점을 계산할 수 있다. 그러나 분기좌굴 해석을 위해서는 좌굴 후 분기경로의 추적을 위한 분기경로 전환 알고리즘이 추가적으로 필요하다. 본문에서는 에너지이론에 기초한 일반 탄성안정이론을 소개하고, 평형경로 추적, 분기 좌굴점을 찾기 위한 직접법과 분기경로 전환에 관한 이론을 전개한다. 분기좌굴 해석예제로 트러스로 이루어진 스타돔, 핀지지의 평면아치, 평면프레임, 3차원 공간프레임의 분기좌굴 해석을 수행하여 본문에서 제시한 수치해석법의 정확성 및 실용성을 검증한다.