• Proceedings of the Korea Water Resources Association Conference
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• 한국수자원학회 2008년도 학술발표회 논문집
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• pp.1565-1569
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• 2008

지난 수십 년 동안, 아시아 태평양 지역 각국은 수자원 접근성 및 인프라의 확충을 포함한 물관리의 다양한 측면에서 현저히 발전하였다고 평가되고 있다. 그러나 급속한 인구 증가 및 경제 성장, 도시화, 기존 수자원의 고갈 등은 아태 지역의 물 수요가 여전히 충족시키지 못하는 원인이다. 또한 기후변화로 인한 환경적 변화를 고려하여 모든 수자원정책의 입안 및 계획이 이루어져야 한다. 경제적 성장률은 전반적으로 높았지만 빈곤 문제는 역시 도시나 농촌을 구분할 것 없이 만성적인 문제로 남아 있으며, 아태 지역 개도국 인구의 16%가 영양실조 상태이며, 2015년까지 그 수를 반감하자는 밀레니엄 개발목표(Millenium Development Goals, MDGs) 달성은 아직 갈 길이 멀다. 또한 아태 지역은 물 관련 재해에 대해 전 세계에서 가장 취약한 지역이며 그로 인한 지속가능한 발전이 지체되고 있다. 1960년부터 2006년까지 물 관련 재해로 인한 전 세계 사상자의 80%에 달하는 60만 명의 사상이 아태 지역에서 발생하였으며, 80억 달러의 경제적 손실이 있었다. 홍수, 가뭄, 쓰나미, 폭풍, 해일 등으로 인한 사회경제적 피해는 최근 들어 더욱 확산되고 있다. 지난 10년간의 급속한 인구 증가로 많은 인구가 범람지대 및 기타 재해 취약 지역에 거주하게 되었으며, 이는 물 인프라 확충을 위한 많은 투자를 요하고 있다. 2006년 3월 멕시코에서 개최된 제4차 세계물포럼의 지역별 추진과정에서 아태 지역은 생태계, 인구, 정치적 제도 및 사회경제적 환경 등 각국의 다양성이 이와 같은 공통된 물문제 해결에 기반이 될 수 있는 요소임에 공감하고 지속적인 수자원 확보와 올바른 수자원관리에 공동의 노력을 기울여 효율적인 메커니즘을 구성을 통해 아태 지역의 사회경제적 발전을 촉구하기로 하였다. 이에 아시아 태평양 물포럼(Asia-Pacific Water Forum)이라는 새로운 이니셔티브가 구성되었고 물 관련 재원 조달 및 인프라 확보를 통해 국경을 초월하는 협력을 증진하고 재해 관리와 조화로운 수자원 개발과 생태 보호등을 위한 일관된 수자원정책 수립과 프로그램 개발 등을 목표로 설정하여 활동을 시작하였다. 아시아 태평양 물정상회의(이하 아태 물정상회의, Asia-Pacific Water Summit(APWS))는 이러한 목표 달성을 구체화하기 위해 각국의 지도자 및 정책입안자에 밀레니엄 개발목표(MDGs) 달성을 위해 물 문제가 얼마나 중요한지 부각시키고 실질적인 정책 결정에 기여하기 위해 제안되었다. 제1차 아태 물정상회의가 2007년 12월 3-4일 양일에 걸쳐 일본 벳부에서 개최되었고, 2008년 G8 정상회담이나 2009년 제5차 세계물포럼에 직접적으로 연계되어 지역 협력을 주도한 가운데 아태 지역 뿐 아니라 전 지구적으로 인류 및 사회 발전을 위한 이정표로 새로운 수자원 네트워크 발돋움의 계기가 되었다.

• Journal of Korean Society of Transportation
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• 제23권5호
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• pp.7-14
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• 2005

Traffic congestion causes enormous social costs as well as loss of travel time and waste of energy. Though the Seoul metropolitan government implemented various forms of transportation policies such as urban road pricing and public transportation reform, traffic volume which across the Seoul metropolitan borders have greatly increased because of housing land development in suburban area. The purpose of this study is to estimate individual's willingness-to-pay(WTP) for extensive implementation of congestion pricing through policy-mix with bus rapid transit(BRT) system. So the field survey interviews carried out. The empirical analysis was done with priority given to the following two topics; derivation of individual WTP and prior evaluation of policy effect from the equity aspect. To estimate individual WTP, we adopted contingent valuation method (CVM). The former is to estimate individual WTP for respondent's maintaining his/her transit pattern when he/she is faced with congestion pricing by using compensating variation(CV) concept. And, the latter aims at evaluating policy effect from the equity aspect by calculating the Proportion of WTP to average income using WTP in income bracket for policy scenarios.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제34권4호
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• pp.1171-1180
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• 2014

The NRCS-CN method is generally used to estimate effective rainfalls in a basin. However, since the curve number which plays a critical role in the NRCS-CN method was originally developed for US watersheds, it is limited to be directly applied to other basins outside the United States. Therefore various modifications have been suggested to revise the NRCS-CN for specific watershed condition. This study introduced the weighted average method and the slope-based CN to estimate effective rainfalls available for Korean watersheds and compared with the observed direct runoff. The overall results achieved from this study indicated that the adjusted slope-based CN considerably increases effective rainfalls in general and makes the duration of effective storm longer. Based on the statistical error analysis performed for various modifications of NRCS-CN, the weighted average method with the adjusted slope-based CN has highest precision with the observed direct runoff. In addition, after analyzing the relation between the initial loss estimated from rainfall-runoff observations and the potential maximum retention from GIS-based data, it turns out that the assumption of linear relationship between the initial loss and the potential maximum retention is not available for Korean watersheds.

• Journal of the Institute of Electronics Engineers of Korea SD
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• 제44권8호
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• pp.80-88
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• 2007

High adaptability and scalability are two critical issues in implementing a very complex system in a single chip. To obtain high adaptability and scalability, novel system design methodology known as communication-based system design has gained large attention from SoC designers. NoC (Network-on-Chip) is such an on-chip communication-based design approach for the next generation SoC design. To provide high adaptability and scalability, NoCs employ network interfaces and routers as their main communication structures and transmit and receive packetized data over such structures. However, data packetization, and routing overhead in terms of run time and area may cost too much compared with conventional SoC communication structure. Therefore, in this research, we propose a novel methodology which automatically generates a hybrid communication structure. In this work, we map traditional pin-to-pin wiring structure for frequent and timing critical communication, and map flexible and scalable structure for infrequent, or highly variable communication patterns. Even though, we simplify the communication structure significantly through our algorithm the connectivity or the scalability of the communication modules are almost maintained as the original NoC design. Using this method, we could improve the timing performance by 49.19%, and the area taken by the communication structure has been reduced by 24.03%.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제27권5호
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• pp.345-352
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• 2014

In this paper, the CAD data for the optimal shape design obtained by isogeometric shape optimization is directly used to fabricate the specimen by using 3D printer for the experimental validation. In a conventional finite element method, the geometric approximation inherent in the mesh leads to the accuracy issue in response analysis and design sensitivity analysis. Furthermore, in the finite element based shape optimization, subsequent communication with CAD description is required in the design optimization process, which results in the loss of optimal design information during the communication. Isogeometric analysis method employs the same NURBS basis functions and control points used in CAD systems, which enables to use exact geometrical properties like normal vector and curvature information in the response analysis and design sensitivity analysis procedure. Also, it vastly simplify the design modification of complex geometries without communicating with the CAD description of geometry during design optimization process. Therefore, the information of optimal design and material volume is exactly reflected to fabricate the specimen for experimental validation. Through the design optimization examples of elasticity problem, it is experimentally shown that the optimal design has higher stiffness than the initial design. Also, the experimental results match very well with the numerical results. Using a non-contact optical 3D deformation measuring system for strain distribution, it is shown that the stress concentration is significantly alleviated in the optimal design compared with the initial design.

• Journal of Radiation Protection and Research
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• 제11권1호
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• pp.57-64
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• 1986

This paper described an improved technical method required for proper evaluation of personnel exposures by means of the photographic dosimeter developed by KAERI in lower gamma or X-ray energy regions, with which response of the dosimeter varies significantly. With calibration of the dosimeter in the energy range from 30 to 300 keV, the beam spectrum was carefully selected and specified it adequately. The absorber combinations and absorber thickness used to obtain the specified X-ray spectra from a constant potential X-ray machine were determined theoretically and also experimentally. A correlation between the density and exposure for the four separate energies, such as $49\;keV_{eff},\;154\;keV_{eff}\;250\;keV_{eff}\;and\;662\;keV$, is experimentally determined. As a result, it can be directly evaluated the exposure from the measured response of dosimeter.

• Journal of the Institute of Electronics Engineers of Korea TC
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• 제46권5호
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• pp.70-77
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• 2009

In an RFID network consisting of a single reader and many tags, a framed and slotted ALOHA, which provides a number of slots for the tags to respond, was introduced for arbitrating a collision among tags' responses. In a framed and slotted ALOHA, the number of slots in each frame should be optimized to attain the maximal efficiency in tag cognizance. While such an optimization necessitates the knowledge about the number of tags, the reader hardly knows it. In this paper, we propose a tag cognizance scheme based on framed and slotted ALOHA, which is characterized by directly taking a Bayes action on the number of slots without estimating the number of tags separately. Specifically, a Bayes action is yielded by solving a decision problem which incorporates the prior distribution the number of tags, the observation on the number of slots in which no tag responds and the loss function reflecting the cognizance rate. Also, a Bayes action in each frame is supported by an evolution of prior distribution for the number of tags. From the simulation results, we observe that the pair of evolving prior distribution and Bayes action forms a robust scheme which attains a certain level of cognizance rate in spite of a high discrepancy between the Due and initially believed numbers of tags. Also, the proposed scheme is confirmed to be able to achieve higher cognizance completion probability than a scheme using classical estimate of the number of tags separately.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제13권2호
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• pp.173-182
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• 1993

This paper presents an algorithm to derive the representative unit hydrograph for the real environment of a watershed. For a given watershed, the conventional methods give several different unit hydrographs by storm events. In this study the LP model is somewhat modified based on the previous study by Mays et also as follows: the objective function is designed to minimize the sum of weighted residuals. An additional constraint of moving average is added to prevent the unit hydrograph from the occurence of oscillation which was not active in Mays's paper. Configuration of rainfall matrix was improved to reduce its dimension in accordance with Diskin's review point. In spite of the superiority of LP approach in terms of representativeness, all the methods were very sensitive to the validity of baseflow separation and rainfall-loss. Several methods of the separations for rainfall excesses and direct runoffs were applied and no preferred methods were identified. This is the matter of judgement considering catchment and rainfall characteristics. This algorithm was applied to a real watershed of the Wi stream in the Nak-dong river. Compared with the IHP results by conventional methods, this optimized representative unit hydrograph demonstrated relatively smaller and shorter values in terms of the peak discharge and the basin lag respectively, and the oscillation of its falling limb successfully eliminated owing to the additional constraints of moving averages.

• Korean Journal of Ecology and Environment
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• 제36권3호통권104호
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• pp.277-285
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• 2003

Temperature profiles were observed to understand seasonal variation of thermal structures in the Juam reservoir from March 2000 to May 2001. Heat flux which affects thermal structures was calculated by observed water temperature and meteorological data. Temperature became homogeneous vertically by convection due to the surface cooling in winter. Maximum heat loss through the surface (109.45W/$m^2$) occurred in December. There was a horizontal gradient of water temperature in winter. The temperature was $3^{\circ}C$ at upstream and $5^{\circ}C$ near the dam. The surface temperature increased by the increase of solar radiation in spring and summer. Maximum heat gained through the surface was 101.95 W/$m^2$ in July. Maximum surface temperature was $29^{\circ}C$ in August, whereas the bottom water was $7^{\circ}C.$ Surface mixed layer became thicker and its temperature decreased by surface heat loss in fall and winter.

• The Journal of Society for e-Business Studies
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• 제23권2호
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• pp.21-31
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• 2018

Korean banknotes are similar in size, and their braille tend to worn out as they get old. These characteristics of Korean banknotes make the blind people, who mainly rely on the braille, even harder to distinguish the banknotes. Not only that, this can even lead to economic loss. There are already existing systems for recognizing the banknotes, but they don't support Korean banknotes. Furthermore, because they are developed as a mobile application, it is not easy for the blind people to use the system. Therefore, in this paper, we develop a Raspberry Pi-based banknote recognition system that not only recognizes the Korean banknotes but also are easily accessible by the blind people. Our system starts recognition with a very simple action of the user, and the blind people can hear the recognition results by sound. In order to choose the best feature extraction algorithm that directly affects the performance of the system, we compare the performance of SIFT, SURF, and ORB, which are representative feature extraction algorithms at present, in real environments. Through experiments in various real environments, we adopted SIFT to implement our system, which showed the highest accuracy of 95%.