• 한국환경과학회지
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• 제15권9호
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• pp.819-827
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• 2006

We study on the dynamic interaction with a simulated physical-biological coupled model response to nutrient reduction scenario in Jinhae Bay. According to the low relative errors, high regression coefficients of COD and DIN, and realistic distribution in comparison to the observation, our coupled model could be applicable for assessing the marine ecosystem response to nutrient input reduction in Jinhae Bay. Due to the new construction and expansion of sewage treatment plant from our government, we reduce 50% nutrient inputs near Masan Bay and sewage treatment plant. COD achieves Level II in Korea standard of the water quality from the middle of the Masan Bay to all around Jinhae Bay except the inner Masan Bay remaining at Level III. When our experiment reduces 50% nutrient inputs near Masan Bay and Dukdong sewage treatment plant simultaneously, COD decreases to about 0.1-1.2 mg/L $(128^{\circ}30'{\sim}128^{\circ}40'\;E,\;35^{\circ}05'{\sim}35^{\circ}11'\;N)$. The COD from the middle of the Masan Bay to Jinhae Bay achieves Level II.

• Wind and Structures
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• 제18권3호
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• pp.281-294
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• 2014

There are several parameters affecting the response of industrial reinforced concrete (RC) chimneys, i.e., the severity of wind and earthquake loads acting to the structure, structural properties such as height and cross section of the chimney, the slenderness property of the structure etc. One of the most important parameter that should be considered while understanding the wind response of industrial RC chimneys is slenderness property. Although there is no certain definition for slenderness effect on these structures, some standards like ASCE-7 define slenderness from different aspects of the structural properties. In the first part of this study, general information about the definition of slenderness in the well-known standards and ten selected industrial RC chimneys are given. In the second part of the study, brief information about wind load standards that are used for calculating wind loads namely ACI 307/98, CICIND 2001, DIN 1056, TS 498 and Eurocode 1 is given. In the third part of the study, calculated wind loads for selected chimneys are represented. In the fourth part of this study, the internal forces obtained from load combinations that are applied to chimneys and some graphs presenting the effect of slenderness on chimneys are given. In the last part of the study, a conclusion and discussion part is taking place.

• Structural Engineering and Mechanics
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• 제50권2호
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• pp.151-161
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• 2014

In this paper, fuel tank of the locomotive ER 24 has been studied. Firstly the behavior of fuel and air during the braking time has been investigated by using a two-phase model. Then, the distribution of pressure on the surface of baffles caused by sloshing has been extracted. Also, the fuel tank has been modeled and analyzed using Finite Element Method (FEM) considering loading conditions suggested by the DIN EN 12663 standard and real boundary conditions. In each loading condition, high stressed areas have been identified. By comparing the distribution of pressure caused by sloshing phenomena and suggested loading conditions, optimization of the tank has been taken into consideration. Moreover, internal baffles have been investigated and by modifying their geometric properties, search of the design space has been done to reach the optimal tank. Then, in order to reduce the mass and manufacturing cost of the fuel tank, Non-dominated Sorting Genetic Algorithm (NSGA-II) and Artificial Neural Networks (ANNs) have been employed. It is shown that compared to the primary design, the optimized fuel tank not only provides the safety conditions, but also reduces mass and manufacturing cost by %39 and %73, respectively.

• 대한수학교육학회지:학교수학
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• 제4권1호
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• pp.15-27
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• 2002

The purpose of this thesis is, through analysing the characteristics of the definitions in Korean school mathematics textbooks, to explore the levels of them. Definitions use din academic mathematics are rigorous. But they should be transformed into various types, which are presented in school mathematics textbooks, with didactical purposes. In this thesis we investigated such types of transformation. With the result of this investigation we tried to identify the levels of the definitions in school mathematics textbooks. We tried to construct, with consideration about methods of definition, frame for analysing the types of the definitions in school mathematics. Methods of definition are classified as connotative method, denotative method, and synonymous method. Especially we identified that connotative method contains logical definition, genetic definition, relational definition, operational definition, and axiomatic definition. With these analyses we made a frame for investigating the characteristics of the definitions in school mathematics textbooks. With this frame we identified concrete types of transformations of methods of definition. We tried to analyse this result with van Hieles' theory about let·els of geometry learning and the mathematical language levels described by Freudenthal, and identify the levels of definitions in school mathematics. We showed the levels of definitions in the geometry area of the Korean school mathematics.

• 한국해양학회지:바다
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• 제9권4호
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• pp.153-163
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• 2004

In order to estimate the nutrient flux of the Seomjin River into the coastal waters of South Sea, and to understand the estuarine reactions during mixing between river water and seawater, we collected surface water along the salinity gradient in the Seomjin River estuary from Mar. 1999 to Apr. 2001. We found that nitrate and silicate were delivered by fluvial input, while phosphate was, supplied from disposed wastes in the Gwangyang Bay. Mean annual flux of dissolved inorganic nitrogen (DIN), phosphate and silicate into the Gwangyang Bay was estimated 10.9 molesㆍsec$^{-1}$(4,820 tonnesㆍyr$^{-1}$), 0.07 molesㆍsec$^{-1}$(68 tonnesㆍyr$^{-1}$), 13.3 molesㆍsec$^{-1}$(11,747 tonnesㆍy$^{-1}$), respectively. An evident removal of phosphate, silicate and ammonium at the mid-salinity zone during the dry season was attributed to the active uptake of phytoplankton, and consequently nutrient flux into the Gwangyang Bay was low. Whereas, during the flood season in summer, conservative or additional distribution of the nutrients was observed in the estuary. As a rsult nutrient flux into the Gwangyang Bay was maintained high. High concentrations of chlorophyll a and the active removal of nutrient during the dry season at the mid-salinity zone suggest that nutrient distribution in the Seomjin River estuary was mainly controlled by biological processes and nutrient fluxes into the Gwangyang Bay might be significantly modified of by the primary production.

• 한국진공학회지
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• 제12권S1호
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• pp.63-66
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• 2003

It is experimentally shown that a $TiO_2$ film on Si(111) substrate was prepared by using the technique of D.C. reaction sputter deposition with $Ar^{+}$ ion beam bombardment, and a layer-like structure was observed from the depth profile of the interface between $TiO_2$ film and Si substrate with Scanning Electron Microscopy and Electron Probe. It was also surprisingly discovered that Ti atoms could be detected at about 9 $\mu$m depth. The $TiO_2$-Si interface bombarded by $Ar^{+}$ ion beams revealed multi-layer structures, a mechanism might be caused by defect diffusion, impurity and matrix relocation. Multi-relocations of impurity and matrix atoms were as a result of profile broadening of the $TiO_2$-Si interface, and the spread due to matrix relocation in this system is shown to exceed much more the spread due to impurity relocation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1631-1632
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• 2015

기술의 발전과 사회/환경변화, WTO/TBT 및 FTA 협정 이행을 위한 국제표준 도입 등 대내 외적 환경에 능동적/선제적으로 대처하기 위하여 국제표준 수준의 규정인 한국전기규정(KEC) 제정(안)을 개발하고 있다. 한국전기규정(KEC)은 국제표준인 IEC를 근간으로 하고, 상세사항은 DIN, BS, NEC 등의 선진표준을 참조, 국내외 표준들의 비교/조사를 통한 개발을 목적으로 제정 중에 있다. 한국전기규정(KEC)은 제1편 공통분야와 제2편 저압전기설비분야, 제3편 고압전기설비분야, 제4편 지능형전력망분야 등 총 4편으로 구성되며 이 중 피뢰시스템은 IEC 62305를 기초로 하여 제정되었다. 본 논문에서 한국전기규정(KEC) 제1편 제5부 피뢰시스템분야에 대한 중요사항에 대해 제시하였다.

• Steel and Composite Structures
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• 제37권1호
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• pp.1-14
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• 2020

Composite beams with corrugated steel webs represent a new innovative system which has emerged in the past decade for medium span in the construction technology. The use of composite beams with corrugated steel webs results in a range of benefits, including flexible spaces and reduced foundation costs in the construction technology. The thin corrugated web affords a significant weight reduction of these beams, compared with hot-rolled or welded ones. In the current research, an optimal designed I-girder beam with corrugated web has been proposed to improve the structural performance of continuous composite girder under bending moment. The experimental program has been conducted for six simply supported composite beams with different loading conditions. The tested specimens are designed by using one of the stochastic techniques called hunting search algorithm. In the optimization process, besides the thickness of concrete slab and studs, corrugated web properties are considered as design variables. The design constraints are respectively implemented from Eurocode 3, BS-8110 and DIN 18-800 Teil-1. The last part of the study focuses on performing a numerical study on composite beams by utilizing finite element analysis and the bending behavior of steel girders with corrugated webs experimentally and numerically verified the results. A nonlinear analysis was carried out using the finite element software ANSYS on the composite beams which were modelled using the elements ten-node high order quadrilateral type.

• Asian Pacific Journal of Cancer Prevention
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• 제15권20호
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• pp.8571-8576
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• 2014

Phytomedicines are believed to have benefits over conventional drugs and are regaining interest in current research. Moringa oleifera is a multi-purpose herbal plant used as human food and an alternative for medicinal purposes worldwide. It has been identified by researchers as a plant with numerous health benefits including nutritional and medicinal advantages. Moringa oleifera contains essential amino acids, carotenoids in leaves, and components with nutraceutical properties, supporting the idea of using this plant as a nutritional supplement or constituent in food preparation. Some nutritional evaluation has been carried out in leaves and stems. An important factor that accounts for the medicinal uses of Moringa oleifera is its very wide range of vital antioxidants, antibiotics and nutrients including vitamins and minerals. Almost all parts from Moringa can be used ad a source for nutrition with other useful values. This mini-review elaborates on details of its health benefits.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 추계학술대회 논문집(Proceeding of the KOSME 2001 Autumn Annual Meeting)
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• pp.71-79
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• 2001

Recently the steel parts used at automobiles are required to be used under high stress more than ever before in need of the weight down. To achieve this requirement of a high strength steel, it must be necessary to decrease inclusion content and surface defect as like decarburization, surface roughness etc.. In this study, the surface conditions are measured to know the influence on fatigue properties by two cases of shot peening of two-stage shot peening and single-stage shot peening. And for this study, three kinds of spring steel(JISG4081-SUP ,SAE 9254, DIN 50CrV4, ) are made. This study shows the outstanding improvement of fatigue properties at the case of two-stage shot peening in the rotary bending fatigue test and this is assumed to be from (1) Decreasing the surface roughness (2) Unchanging the surface hardness (3) Increasing the compressive residual stress But, results also show fatigue failures originated at inclusion near surface, and this inclusion type is turned out to be a alumina of high hardness.