• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.365-365
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• 2017

강우의 공간분포는 홍수수문곡선에 큰 영향을 미친다. 이것은 총강우량이 같더라도 강우의 공간분포 특성에 따라 홍수수문곡선 및 첨두유량의 크기가 다를 수 있다는 것을 의미한다. 따라서 강우의 공간분포는 홍수량 산정과 홍수해석은 물론 수자원 설계에 큰 영향을 미칠 수 있다. 본 연구에서는 안동댐유역을 대상으로 물리적 기반의 분포형 모형인 GRM 모형과 공간확장자료 생성방법을 사용하여 47개 미계측유역에 대해 홍수유출 시계열자료를 생성하고 3개 관측유역을 포함한 총 50개 유역에 대해 첨두유량을 추출하여 분석함으로써 강우의 공간분포가 유출에 미치는 영향을 실제유역과 실제사상에 대해 자세히 분석하였다. 공간확장자료 생성방법은 보정 및 검증유역에서 모의유량이 관측유량을 적절히 모의한다면 추정된 매개변수값들을 상류지역에 있는 미계측유역에 적용하여 유량자료를 생성하는 방법이다. 1989년부터 2009년까지의 강우와 유출자료의 질이 좋은 20개의 사상을 추출하고 이 사상들과 3개 관측유역에 대해 GRM 모형의 매개변수들을 보정 및 검증하였다. 그 결과 NSE > 0.5, PBIAS ${\pm}30%$, 그리고 수정상관계수인 $_{mod}>0.6$의 적절한 모형효율 통계결과를 얻었다. 강우의 공간분포가 유출에 미치는 영향을 조사하기 위해 이 추정된 매개변수와 실제강우(강우의 공간분포를 고려한 강우) 및 공간평균강우(실제강우를 공간적으로 평균한 강우)를 사용하여 50개 유역의 홍수유출 시계열자료를 생성하였으며 이 시계열 자료 중 첨두유량을 추출하여 분석하였다. 그 결과 공간평균강우에 의한 첨두유량의 분포는 실제강우에 의한 첨두유량의 분포와 차이가 있었다. 20개 사상중 13개의 사상은 실제강우와 공간평균강우에 의한 첨두유량의 분포가 비슷하거나 공간평균강우에 의한 첨두유량의 분포가 실제강우에 의한 첨두유량의 분포보다 약간 좁아지는 차이가 있었다. 하지만 나머지 7개 사상의 경우에는 공간평균강우에 의한 첨두유량의 분포가 실제강우에 의한 첨두유량의 분포보다 크게 좁아지는 것을 보였다. 이것은 전체사상의 약 35 %에 대해서는 강우의 공간적 변동성을 고려하지 않고 홍수유출을 모의한다면 적절하지 않은 첨두유량 모의결과를 얻을 수 있다는 것을 나타내며 또한 홍수체적에 대해서도 적절하지 않은 모의결과를 얻을 수 있다는 것을 의미한다. 이것은 또한 강우관측소의 밀도가 홍수유출 모의 시 매우 중요하다는 것을 의미한다. 따라서 홍수량 산정 또는 수자원 설계 시 강우의 시간분포 뿐만 아니라 공간분포 또한 고려해야 한다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.1
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• pp.37-42
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• 2021

The effect of chemical composition on the structural and thermal properties of TiZrN thin films was studied. As the Zr fraction in the deposited TixZr1-xN (x = 0.87, 0.82, 0.7, 0.6, and 0.28) increased, microstructural changes consisted of reduction in the grain size and a gradual transition from columnar structure to granular structure were observed. In addition, it was also confirmed that a gradual crystal phase transition from TiN to TiZrN has occurred as the Zr fraction increased up to 0.4. After heat treatment at 900℃, Ti0.82Zr0.18N and Ti0.7Zr0.3N layers were converted to a form in which rutile phase TiO2 and TiZrO4 oxides coexist, while Ti0.6Zr0.4N layer was converted to TiZrO4 oxide. Among the five compositions of TiZrN films, the Ti0.6Zr0.4N showed the best high temperature stability and produced a significant enhancement in the thermal oxidation resistance of Inconel 617 through suppressing the surface diffusion of Cr caused by thermal oxidation of the Inconel 617 substrate.

• Fire Science and Engineering
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• v.17 no.2
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• pp.1-5
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• 2003

Recently, the occurrences of electrical fire have been suppressed by a residual current protective devices(RCD), a molded case circuit breaker(MCCB) and a fuse in case of an earth leakage, a short circuit and an over current. But it is impossible for the RCD to break the circuit in the case of the conductor fractures, the failure of pressure contacts on connecting points and the momentary short circuit of low voltage wiring. Therefore, it is require to study the constructive problem of the RCD. In this paper, we have tested the operation characteristics of the RCD according to the R load and R-L load in the conductor fractures, the failure of pressure contacts on connecting points and the momentary short circuit of low voltage wiring.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.3
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• pp.416-420
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• 2002

Traditional queueing analyses are very useful for designing a network's capacity and predicting there performances, however most of the predicted results from the queueing analyses are quite different from the realistic measured performance. And recent empirical studies on LAN, WAN and VBR traffic characteristics have indicated that the models used in the traditional Poisson assumption can't properly predict the real traffic properties due to under estimation of the long range dependence of network traffic and self-similarity In this parer self-similar characteristics over statistical approaches and real time network traffic measurements are estimated It is also shown that the self- similar traffic reflects network traffic characteristics by comparing source model.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.104-107
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• 2002

Traditional queueing analyses are very useful for designing a network's capacity and predicting there performances, however most of the predicted results from the queueing analyses are quite different from the realistic measured performance. And recent empirical studies on LAN, WAN and VBR traffic characteristics have indicated that the models used in the traditional Poisson assumption can't properly predict the real traffic properties due to under estimation of the long range dependence of network traffic and self-similarity. In this paper self-similar characteristics over statistical approaches and real time network traffic measurements are estimated. It is also shown that the self-similar traffic reflects network traffic characteristics by comparing source model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7964-7970
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• 2015

In enclosed areas such as railway tunnels, the heat and smoke generated by a fire can pose a tremendous risk to the life of passengers. To prevent or mitigate such scenarios, fire detectors are installed for early fire detection. This numerical study is preformed for establishing the method of detecting performance of fire detectors installed on railway tunnels. Numerical analysis are conducted using the fire dynamics simulator, developed by the NIST. The temperature of the tunnel walls is determined using the assumed exterior structure of the tunnel. In addition, the detection times of detectors installed at different locations in the tunnel are obtained for different sizes of the fire source, and the results are compared and analyzed.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.148.1-148.1
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• 2013

투어멀린는 $XY_3Z_6(Si_6O_{18})(BO_3)_3$ 화학 방정식을 가진 광물로써 조성에 따라 alkali 투어멀린, calcic 투어멀린, X-site vacant 투어멀린 등으로 불린다. 투어멀린 특성과 화학성분에 따라 종을 구분하는데, 주된 종들은 엘바이트, 리디코타이트, 드라바이트, 우바이트, 숄이 있다. 일반적으로 적색 투어멀린의 발색 원인은 Mn, Fe 그리고 Cu의 함량에 따라 색상의 차이를 나타낸다. 본 연구에서 우리는 10MeV 에너지와 $1{\times}10^{17}cm^2$ 조건에서 전자빔을 수행 한 후 투어멀린의 컬러 변화를 관찰하였다. 자외선-가시광선 분광분석결과 모든 시료는 전자빔 조사 후 530 nm의 $Mn^{3+}$부근의 흡수 peak들이 증가하는 것이 관찰되었다. 이는 $Mn^{2+}$에서 $Mn^{3+}$ 이동 때문이여, $Mn^{3+}$는 Y-site에서 O(1)H-O(3)H 축에 따라 Jann-taller 변형으로 안정된 구조를 가지게 된다. 따라서 전자빔 조사 후 적색으로 변하게 되는 것이다. 또한 전자빔 조사 후 컬러가 모두 변했지만 상온에 뒀을 때 변화 된 컬러가 원래의 색으로 되돌아가는 향상을 보였다. 이는 전자빔 조사 후 전자가 튕겨져 나가서 불안정한 상태로 존재하고 있다가 상온의 열에 의한 에너지에 통해 다시 안정된 상태로 되돌아오는 결과로 볼 수 있다. 또한 우리는 WD-XRF를 통해 미량의 Mn 원소함량 차이에 따라 전자빔 조사 시 컬러 변화에 미치는 영향에 대해 확인할 수 있었다. 그리고 적외선 분광분석에서는 4,300-4,600 $cm^{-1}$사이에 특징적인 밴드들이 관찰되었다.

• Economic and Environmental Geology
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• v.49 no.2
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• pp.77-88
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• 2016

Chrysotile is a 1:1 sheet silicate mineral belonging to serpentine group. It has been highlighted studies because of uses, shapes and structural characteristics of the fibrous chrysotile. However, it was designated as Class 1 carcinogen, so high attentions were being placed on detoxification studies of chrysotile. The objectives of this study were to investigate changes of mineralogical characteristics of chrysotile and to suggest detoxification mechanism of chrysotile by thermal decomposition. Samples for this study were obtained from LAB Chrysotile mine in Canada. The samples were heated in air in the range of 600 to $1,300^{\circ}C$. Changes of mineralogical characteristics such as crystal structure, shape, and chemical composition of the chrysotile fibers were examined by TG-DTA, XRD, FT-IR, TEM-EDS and SEM-EDS analyses. As a result of thermal decomposition, the fibrous chrysotile having hollow tube structure was dehydroxylated at $600-650^{\circ}C$ and transformed to disordered chrysotile by removal of OH at the octahedral sheet (MgOH) (Dehydroxylation 1). Upon increasing temperature, it was transformed to forsterite ($Mg_2SiO_4$) at $820^{\circ}C$ by rearrangement of Mg, Si and O (Dehydroxylation 2). In addition, crystal structure of forsterite had begun to transform at $800^{\circ}C$, and gradually grown 3-dimensionally to enstatite ($MgSiO_3$) by recrystallization after the heating above $1,100^{\circ}C$. And then finally transformed to spherical minerals. This study showed chrysotile structure was collapsed about $600-700^{\circ}C$ by dehydroxylation. And then the fibrous chrysotile was transformed to forsterite and enstatite, as non-hazardous minerals. Therefore, this study indicates heat treatment can be used to detoxification of chrysotile.

• Applied Biological Chemistry
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• v.43 no.3
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• pp.207-212
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• 2000

Physicochemical and sensory characteristics of soybean sprouts from domestic and foreign soybean cultivars were investigated. 100-seed weights of domestic cultivars were much larger than that of Canadian cultivar and recommended cultivars were larger than traditional cultivars. Water absorption of soybeans increased sharply to initial 6 hrs during steeping, and did not change much thereafter. In all soybean cultivars 16 amino acids were detected and the contents of Asp, Glu, Lys and Arg were more than 50% of total amino acid contents. All soybean cultivars showed some difference in composition of fatty acids and the content of linoleic acid was highest. The contents of K and P were high and those of Fe and Zn were low. The compression force of hypocotyl after cultivation was the highest in Eunha and the lowest in Junjeori and the compression force of cotyledon was the highest in Danyeop and the lowest in Canadian cultivar. Qualitative discription analysis for cooked soybean sprouts and soups showed significant difference in 6 characteristics of yellowness of cotyledon, size of cotyledon and so on.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.29-36
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• 2017

In this study, acombined cogeneration power plant produced two types of thermal energy and electric or mechanical power in a single process. The performance of each component of the gas turbine-combined cogeneration system was expressed as a function of the fuel consumption of the entire system, and the heat and electricity performance of each component. The entire system consisted of two gas turbines in the upper system, and two heat recovery steam generators (HRSG), a steam turbine, and two district heat exchangers in the lower system. In the gas turbine combined cogeneration system, the performance test after 10,000 hours of operation time, which is subject to an ASME PTC 46 performance test, was carried out by the installation of various experimental facilities. The performance of the overall output and power plant efficiency was also analyzed. Based on the performance test data, the test results were compared to confirm the change in performance. This study performed thermodynamic system analysis of gas turbines, heat recovery steam generators, and steam turbines to obtain the theoretical results. A comparison was made between the theoretical and actual values of the total heat generation value of the entire system and the heat released to the atmosphere, as well as the theoretical and actual efficiencies of the electrical output and thermal output. The test results for the performance characteristics of the gas turbine combined cogeneration power plant were compared with the thermodynamic efficiency characteristics and an error of 0.3% was found.