• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 추계학술대회 논문집(제1권)
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• pp.57-62
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• 2006

동북아의 허브항만으로 건설중인 부산신항만은 태풍 매미로 인해 480억원에 이르는 큰 피해를 입었다. 국내의 현행 항만설계기준을 보면 항만 정온도 기준은 선박규모별 항내 한계파고만이 규정되어있다. 그러나, 항만의 연중 이용일수를 나타내는 항만 가동률은 화물을 싣고 내리는 하역작업의 효율에 달려있으며, 하역효율은 다시 접안선박의 파랑에 의한 동요 및 하역기계의 성능에 따라 결정된다. 선박의 동요는 파고뿐만 아니라 주기에 따라서도 충분히 달라질 수 있으며 해 ${\cdot}$ 조류, 바람 등의 외력조건, 계류시스템의 특성과 선박의 제원 등의 복합적인 요인에 의하여 결정된다. 본 연구에서는 수치실험 및 관측 자료를 통해 평상시의 항만 가동률을 산정하고자 한다. 특히, 부산신항만의 개발초기단계에서의 계획으로부터 수심을 증심시킴과 아울러, 매립범위 및 해안선 형태 등 다양한 변화가 건설과정에서 나타났고 이를 본 연구에서 반영하여 상세해역과 장래 개발해역 둥에서 항만가동율을 재산정하였다. 파랑변형과정의 이해와 분석을 돕기 위하여 관련해역에서 정상상태 스펙트럼모델과 확장 완경사 파랑 모델을 부산신항역에 적용하여 항만반응 특성을 분석하였다.

• 한국주거학회논문집
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• 제21권2호
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• pp.101-109
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• 2010

Various environmental problems due to rapid industrialization and urbanization have worsened to such an extent that they threaten the environmental restitution of the globe and become a critical international issue. Korean government has presented the concept of green growth as a new state vision for the next 60 years and is making efforts to solve these environmental problems. Daegu Metropolitan City has faced various environmental problems including overpopulation of the city, traffic pollution, household waste accumulation and the green zone problem because of the increase of urbanization over the last few decades. As such urbanization continues, the quality of residential environments is rapidly deteriorating and the intensive use of the land leads to an increase of building area, raising the temperatures of cities. There have therefore been demands for healthy, pleasant and satisfying residential environments and for the improvement of existing residential environments, and this demand has been fully recognized by society. Nevertheless, current residential complex developments concentrate only on raising the efficiency of land use. In related laws of the past (Daegu Metropolitan City, Urban Planning Municipal Ordinance as of October 10, 2003) an attempt was made to impose a standard to segmentalize the building-to-land ratio, floor area ratio and regulations of number of floors vertically. However, these laws have now been abolished and the regulations are being eased. The purpose of this study was to analyze the characteristics of the floating wind before and after the vertical segmentation of residential areas (Daegu Metropolitan City, Urban Planning Municipal Ordinance as of October 10, 2003) by using KLAM_21, a model that enables analysis and prediction of the flow and generation of cold wind. The purpose is also to present a plan to improve the quality of residential areas when developing a building lot and redeveloping housing areas.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2009년도 추계학술발표대회 논문집
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• pp.109-112
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• 2009

Various environmental problems due to the rapid industralization and urbanization have been worsened as much as to threaten the environmental restitution of globe and become a critical international issue. Korean government presented the green growth as a new state vision for 60 years afterwards and is making efforts to solve the environmental problems. Daegu metropolitan city has faced various environmental problems including overpopulation of cities, traffic pollution, household wastes and green zone problem because of urbanization for the last decades. As such urbanism continues, the quality of residential environment is rapidly deteriorating and the intensive use of land leads to increase of building area raising the temperature of cities. Therefore there have been demands for the healthy, pleasant and satisfying residential environment and the improvement of residential environment and such recognition rises from society in full measure. Nevertheless the current residential complex concentrates only on raising the efficiency of land use. Related laws in the past(Daegu Metropolitan City, Urban Planning Municipal Ordinance as of October 10, 2003) tried to prepare a standard to segmentalize the building-to-land ratio, floor area ratio and regulations of number of floors vertically, but currently it is abolished and the regulations are becoming eased. The purpose of this study was to analyze the characteristics of the floating wind before and after the vertical segmentation of residential areas(Daegu Metropolitan City, Urban Planning Municipal Ordinance as of October 10, 2003) by using KLAM_21, a model that enables analysing and predicting the flow and generation of clod wind, and to present a plan to improve the quality of residential areas afterwards when developing building lot and re-developing housing areas.

• 콘크리트학회논문집
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• 제17권5호
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• pp.727-734
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• 2005

최근 증가하고 있는 초고층 주거용 구조물 중 많은 수가 건축적인 이유로 인해 건물골조시스템을 주요 지진저항시스템으로 채택하고 있다. 그러나 KBC 2005를 적용하여 건물골조시스템을 설계할 때 기준에서 언급되지 않거나 모호한 표현으로 인해 설계자는 많은 어려움을 겪을 수 있다. 특히 정적$\cdot$동적 해석시 RC부재의 균열단면을 고려한 유효강성의 적용 방법, 변형 적합성을 고려한 골조의 설계법 등에서 어려움을 겪을 수 있다. 이에 대하여 전단벽과 골조(플랫 플레이트)로 이루어진 전형적인 건물골조시스템의 건물에 대해 KBC 2005를 적용하고 기준의 불명확한 부분에 대해서 여러 방법을 적용하여 해석한 결과 기준의 모호한 언급이나 설계자의 임의의 판단으로 인해 층간변위비, 전단벽 및 연결보의 요구강도 등에서 매우 큰 차이가 발생하였으며, 동일한 건물을 이중골조시스템으로 설계한 경우에 비해 건물골조시스템으로 설계한 경우 변형 적합성의 요구로 인해 전단벽의 높은 요구강도 뿐만 아니라 골조에서도 높은 연성이 요구되었다.

• Nuclear Engineering and Technology
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• 제48권6호
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• pp.1291-1302
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• 2016

This paper presents a new and efficient scheme to determine the optimal neutron source position in a model near-equilibrium pressurized water reactor, which is based on the OPR1000 Hanul Unit 3 Cycle 7 configuration. The proposed scheme particularly assigns importance of source positions according to the local adjoint flux distribution. In this research, detailed pin-by-pin reactor adjoint fluxes are determined by using the Monte Carlo KENO-VI code from solutions of the reactor homogeneous critical adjoint transport equations. The adjoint fluxes at each allowable source position are subsequently ranked to yield four candidate positions with the four highest adjoint fluxes. The study next simulates ex-core detector responses using the Monte Carlo MAVRIC code by assuming a neutron source is installed in one of the four candidate positions. The calculation is repeated for all positions. These detector responses are later converted into an inverse count rate ratio curve for each candidate source position. The study confirms that the optimal source position is the one with very high adjoint fluxes and detector responses, which is interestingly the original source position in the OPR1000 core, as it yields an inverse count rate ratio curve closest to the traditional 1/M line. The current work also clearly demonstrates that the proposed adjoint flux-based approach can be used to efficiently determine the optimal geometry for a neutron source and a detector in a modern pressurized water reactor core.

• Current Research on Agriculture and Life Sciences
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• 제26권
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• pp.7-15
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• 2008

This research is significant in terms of estimating the validity by setting evaluation items in view of integrating not only original beauty and visual areas but also natural ecological areas based on questionnaire. The results are as follows. 1) According to literature study, 17 items such as variety, the character of sites in terms of landscape, the beauty of landscape, visibility, and ratio of green visibility are selected. Also, 21 items such as variety of animals and plants species, size of green area, and ecological naturalness are selected in the area of landscape ecological resources. 2) As a result of questionnaire of the group of landscape experts, animals and plants ecological areas show 5.6341, the highest in importance analysis according to assessment areas. Also, as a result of importance analysis on items in each area, for example, in the area of visual resources, the item of skyline analysis is 6.0488, the highest. 3) As a result of corelation of item meaning on landscape effect assesment, for example, meaningness of psychological assessment item and landscape site item indicate 0.710, the highest coefficient correlation. 4) As critical assessment items per unit project, items such as damage minimization of original land features for project in terms of point, ratio of green visibility, variety of animals and plants species marked above 8.0 as high important medium. The project in terms of line, minimization of original land features, preservation of worthy biotope showed high point and the character of sites in terms of landscape, minimization of original land features, the size of green area, and analysis of skyline marked above 8.5 as high importance points. On the contrary, items for climate and soil showed relatively low points.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.860-866
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• 2022

An accurate prediction of the pressure drop along the flow paths is crucial in the design of advanced passive systems cooled by heavy liquid metal coolants. To date, a generic pressure drop correlation over spacer grids by Rehme has been applied extensively, which was obtained from substantial experimental data with multiple types of components. However, a few experimental studies have reported that the correlation may give large discrepancies. To provide a more reliable correlation for ring-type spacer grids, the current numerical study aims at figuring out the most critical factor among four hypothetical parameters, namely the flow area blockage ratio, number of fuel rods, type of fluid, and thickness of the spacer grid in the flow direction. Through a set of computational fluid dynamics simulations, we observed that the flow area blockage ratio dominantly influences the pressure loss characteristics, and thus its dependence should be more emphasized, whereas the other parameters have little impact. Hence, we suggest a new correlation for the drag coefficient as C_B = C_ν,m/ε^2.7, where C_ν,m is formulated by a nonlinear fit of simulation data such that C_ν,m = -11.33 ln(0.02 ln(Re_b)).

• Structural Engineering and Mechanics
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• 제86권4호
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• pp.443-459
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• 2023

This study investigates the theoretical thermal buckling analyses of thick porous rectangular functionally graded (FG) plates with different geometrical boundary conditions resting on a Winkler-Pasternak elastic foundation using a new higher-order shear deformation theory (HSDT). This new theory has only four unknowns and involves indeterminate integral variables in which no shear correction factor is required. The variation of material properties across the plate's thickness is considered continuous and varied following a simple power law as a function of volume fractions of the constituents. The effect of porosity with two different types of distribution is also included. The current formulation considers the Von Karman nonlinearity, and the stability equations are developed using the virtual works principle. The thermal gradients are involved and assumed to change across the FG plate's thickness according to nonlinear, linear, and uniform distributions. The accuracy of the newly proposed theory has been validated by comparing the present results with the results obtained from the previously published theories. The effects of porosity, boundary conditions, foundation parameters, power index, plate aspect ratio, and side-to-thickness ratio on the critical buckling temperature are studied and discussed in detail.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.187-187
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• 2012

Solution-processed metal-alloy oxides such as indium zinc oxide (IZO), indium gallium zinc oxide (IGZO) has been extensively researched due to their high electron mobility, environmental stability, optical transparency, and solution-processibility. In spite of their excellent material properties, however, there remains a challenging problem for utilizing IZO or IGZO in electronic devices: the supply shortage of indium (In). The cost of indium is high, what is more, indium is becoming more expensive and scarce and thus strategically important. Therefore, developing an alternative route to improve carrier mobility of solution-processable ZnO is critical and essential. Here, we introduce a simple route to achieve high-performance and low-temperature solution-processed ZnO thin film transistors (TFTs) by employing alkali-metal doping such as Li, Na, K or Rb. Li-doped ZnO TFTs exhibited excellent device performance with a field-effect mobility of $7.3cm^2{\cdot}V-1{\cdot}s-1$ and an on/off current ratio of more than 107. Also, in case of higher drain voltage operation (VD=60V), the field effect mobility increased up to $11.45cm^2{\cdot}V-1{\cdot}s-1$. These all alkali metal doped ZnO TFTs were fabricated at maximum process temperature as low as $300^{\circ}C$. Moreover, low-voltage operating ZnO TFTs was fabricated with the ion gel gate dielectrics. The ultra high capacitance of the ion gel gate dielectrics allowed high on-current operation at low voltage. These devices also showed excellent operational stability.

• Journal of Preventive Medicine and Public Health
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• 제52권2호
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• pp.72-81
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• 2019

Objectives: The current study presents a new conceptual framework for physician-induced demand that comprises several influential components and their interactions. Methods: This framework was developed on the basis of the conceptual model proposed by Labelle. To identify the components that influenced induced demand and their interactions, a scoping review was conducted (from January 1980 to January 2017). Additionally, an expert panel was formed to formulate and expand the framework. Results: The developed framework comprises 2 main sets of components. First, the supply side includes 9 components: physicians' incentive for pecuniary profit or meeting their target income, physicians' current income, the physician/population ratio, service price (tariff), payment method, consultation time, type of employment of physicians, observable characteristics of the physician, and type and size of the hospital. Second, the demand side includes 3 components: patients' observable characteristics, patients' non-clinical characteristics, and insurance coverage. Conclusions: A conceptual framework that can clearly describe interactions between the components that influence induced demand is a critical step in providing a scientific basis for understanding physicians' behavior, particularly in the field of health economics.