• 수산해양기술연구
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• 제53권4호
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• pp.423-429
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• 2017

As invigoration plan of the marine tourism, Busan City has the plan to operate the cruise ship inside of the harbor, but the area has narrow water way with heavy traffic. As a result it is requested to evaluate the safety for the preparation of actual navigation. In this study, the Ship Handling Simulation (SHS) Assessment was conducted, which is regulated by the Maritime Traffic Safety Audit Scheme (MTSAS) in compliance with the Marine Safety Law and the Maritime Traffic Risk Assessment System based on the Electronic Chart Display and Information System (ECDIS). The proximity assessment, control assessment and subjective assessment were implemented, which is enacted by the Marine Safety Law by using the SHS. In the case of proximity assessment, the probability of trespass was not analyzed. As the control assessment, the swept path was measured at 11.7 m and 11.5 m for port entry and port departure respectively, which exceeded the width of the model vessel, 10.4 m over; it was considered as a marginal factor. As a result of the subjective evaluation of the navigator, there would be no difficulty on ship maneuvering by paying particular attention to the mooring vessel nearby the Busan Bridge and Yeongdo Bridge as well as the coming vessel from the invisible sea area when the vessel is entering and departing the port. The Marine Traffic Risk Assessment System analyzed as [Cautious] level until the vessel passed the Busan bridge and the curved area at 5 kts and it became to [Dangerous] level from where it left 75 m to the Busan Bridge. When the vessel passed the Busan Bridge and the curved area at 10 kts and entered the narrow area, it indicated the [Dangerous] level and became to [Very dangerous] level from where it left 410 m to the Busan bridge. In conclusion, the vessel should maintain at the speed of 5 kts to reduce the risk when it passes this area.

• 한국조경학회지
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• 제32권4호
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• pp.28-38
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• 2004

Korean goral (Nemorhaedus caudatus raddeanus) is one of the endangered species in Korea, and the rugged terrain of the Soraksan National Park (373㎢) is a critical habitat for the species. But the goral population is threatened by habitat fragmentation caused by roads and hiking trails. The objective of this study was to develop a potential habitat suitability model for Korean goral in the park, and the model was based on the concepts of fuzzy set theory and multi-criteria evaluation. The process of the suitability modeling could be divided into three steps. First, data for the modeling was collected by using field work and a literature survey. Collected data included 204 points of GPS data obtained through a goral trace survey and through the number of daily visitors to each hiking trail during the peak season of the park. Second, fuzzy set theory was employed for building a GIS data base related to environmental factors affecting the suitability of the goral habitat. Finally, a multiple-criteria evaluation was performed as the final step towards a goral habitat suitability model. The results of the study were as follows. First, characteristics of suitable habitats were the proximity to rock cliffs, scattered pine (Pinus densiflora) patches, ridges, the elevation of 700∼800m, and the aspect of south and southeast. Second, the habitat suitability model had a high classification accuracy of 93.9％ for the analysis site, and 95.7％ for the validation site at a cut off value of 0.5. Finally, 11.7％ of habitatwith more than 0.5 of habitat suitability index was affected by roads and hiking trails in the park.

• 한국융합학회논문지
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• 제13권2호
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• pp.235-248
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• 2022

부모-자식 인터랙티브 게임 가구에 기초한 설계지표의 연구는 설계사들이 관련 상품의 설계의 장단점을 정량적으로 분석할 수 있게 하여 설계의 질을 관리하고 향상하는데 긍정적인 도움이 된다. 본 연구에서는 AHP와 TOPSIS를 결합하여 3가지 설계기준과 26가지 설계지수의 평가모델을 제안하였다. 각 지표에 대한 전문가들의 채점, 계산 및 일관성 테스트를 거쳐 각 설계지표의 가중치를 얻어낸 다음 각 지표의 중요정도에 따라 지표분류를 진행하였다. 분류결과 설계지표들을 8개의 중요지표와 11개의 보조지표, 7개의 일반지표로 분류하였다. 사례 연구에서는 TOPIS를 이용하였다. 세 종의 부모-자식 등반 게임 가구의 디자인 표본을 분석해 본 결과 세 표본의 상대 근접도는 최종적으로 각각 0.505, 0281 및 0.640 이였다. 연구를 통하여 AHP-TOPSIS 방법이 설계방안의 장단점을 과학적으로 효과적으로 분류 및 선별하고 관련 제품의 연구 및 개발에 참고를 제공할 수 있는 아주 유용한 방법이라는 것이 밝혀졌다.

• Journal of Power Electronics
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• 제18권4호
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• pp.1268-1277
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• 2018

A relatively high operating frequency is required for efficient wireless power transfer (WPT). However, the alternating current (AC) resistance of coils increases sharply with operating frequency, which possibly degrades overall efficiency. Hence, the evaluation of coil AC resistance is critical in selecting operating frequency to achieve good efficiency. For a Litz wire coil, AC resistance is attributed to the magnetic field, which leads to the skin effect, the proximity effect, and the corresponding conductive resistance and inductive resistance in the coil. A numerical calculation method based on the Biot-Savart law is proposed to calculate magnetic field strength over strands in Litz wire planar spiral coils to evaluate their AC resistance. An optimized frequency can be found to achieve the maximum efficiency of a WPT system based on the predicted resistance. Sample coils are manufactured to verify the resistance analysis method. A prototype WPT system is set up to conduct the experiments. The experiments show that the proposed method can accurately predict the AC resistance of Litz wire planar spiral coils and the optimized operating frequency for maximum efficiency.

• 환경영향평가
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• 제4권1호
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• pp.17-23
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• 1995

To assess preliminarily the contamination potential of water resources including groundwater owing to the hydrogeological characteristics of landfill site and the potential impact to humans and animals through contamination of water resources by leachate, "Landfill Site Preliminary Assessment Model(LASPAS)" was contrived. LASPAS could help them proritization of remediation of landfil sites by the convenient and relatively simple evaluation method of landfill site features. LASPAS was designd to aliot numerical ratings to landfill site related factors undermentioned; 1) hydrogeological factors such as hydraulic conductivity of aquifer, thickness of confining layer over aquifer, topographical slope, net recharge, and subsurface containment 2) water resources contamination factors of impacts on receptors such as proximity to drinking water supply, substitutability of drinking water supply, type of use of water resources, known impact on drinking water supply, and flood potential.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.335-345
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• 2017

Recently, location systems using RFID technology have been studied in indoor environments. However, the existing techniques require high computational cost to compute the location of a moving object because they compare the location proximity of all reference tags and objects. In this paper, we propose an RFID based location positioning scheme using event filtering, which reduces the computation cost of calculating the locations of moving objects while maintaining the accuracy of location estimation. In addition, we propose an incremental location update policy to reduce the location update cost for moving objects. We also compare the proposed scheme with one of the localization schemes, LANDMARC using a performance evaluation. As a result, the proposed scheme outperforms LANDMARC in terms of the computational cost of location estimation. The proposed scheme also reduces the cost of location update by using the RFID-based update policy.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권5호
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• pp.351-357
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• 2004

In this paper, we present an analytical method that provides fast and efficient evaluation of the conversion efficiency for switching power supplies. In the proposed method, the conduction losses are evaluated by calculating the effective values of the ideal current waveform first and incorporating them into an exact equivalent circuit model of the switching power supply that includes all the parasitic resistances of the circuit components. While the winding losses and core losses are accurately accounted for the magnetic components, the skin and proximity effects are assumed to be negligible in order to simplify the analysis. The validity and accuracy of the proposed method are verified with experiments on a prototype active-clamped forward converter with synchronous rectification. An excellent correlation between the experiments and theories are obtained for the input voltages of 36-75 V with 4-6 MOSFETs employed for the synchronous rectification.

• Journal of Korean Neurosurgical Society
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• 제57권6호
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• pp.465-468
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• 2015

Hemangioblastomas in the pituitary stalk are especially rare. Most pituitary stalk hemangioblastomas reported in the literature were associated with von Hippel-Lindau (VHL) disease. Here, we report only the 3rd case of sporadic pituitary stalk hemangioblastoma diagnosed in a 60-year-old woman. Despite the danger of potential complications due to excessive vascularity or proximity to important neural structures, the tumor in our case was successfully removed while preserving pituitary function. In this case, complete surgical excision was shown to be an effective treatment option for symptomatic pituitary stalk hemangioblastoma, and we suggest careful evaluation of any highly enhancing mass with a signal void in the pituitary stalk preoperatively, even if no VHL disease is evident.

• 산업기술연구
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• 제16권
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• pp.247-256
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• 1996

The multilevel grid file(MLGF) is a dynamic multidimensional file organization supporting multi-attribute accesses efficiently. The paper proposes new method for batch-constructing MLGFs. Our method consists of two phases. The first phase begins by relocating all the objects in order that logically adjacent objects in multidimensional domain space are clustered in one dimensional physical space. For this, our method employs the Z-ordering scheme, which effectively maps multidimensional space into one dimensional space preserving proximity. The second phase paginates the relocated objects and creates leaf level directory entries, each of which corresponds to a object page. Simultaneously, it performs same actions on the directory entries recursively in a bottom-up fashion until the root directory fits in a page. For performance evaluation, we analyze our method in terms of the number of page accesses. The result shows the optimality of our method.

• 한국해양공학회지
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• 제19권3호
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• pp.25-30
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• 2005

To predict rolling performance for a barge-type FPSO, the evaluation of correct nonlinear roll damping is critical. The square section of FPSO causes a considerable viscous damping effect. Free roll decay tests were carried out to estimate nonlinear roll damping for a barge-type FPSO, under three different conditions. The roll motion RAO was deduced from model tests in the wave condition of the wideband spectrum. In numerical calculation, the quadratic damping was considered as equivalent linear damping, using the results of free roll decay test. Tested roll performance in the JONSWAP wave spectrum was compared with numerical results. These two results shaw good agreement, in spite of the proximity of peak wave period and roll natural period.