• Journal of Wetlands Research
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• v.19 no.4
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• pp.484-490
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• 2017

In order to examine flow characteristics according to the shape of the meandering low flow channel in the compound cross section typed straight channel, we assumed the representative channel type in Korea and confirmed the validity of the 3D numerical simulation by carrying out the hydraulic model. Based on this study, numerical simulations were also conducted on other types of river channel. As a result of the numerical model test (using the velocity value measured by the water depth observation from the hydraulic model test), it was confirmed that the numerical simulation results are in good agreement with the numerical simulation results. As a result of analyzing the flow field according to the changes in the shape of the low flow channel, it was confirmed that the secondary flow examined in the previous studies occurred. Also, it was confirmed that the maximum flow velocity point moves according to the expansion cross sectional area of flow in high flow plain. Ultimately, it is thought that it is necessary to understand the position of the water impingement (which is an important factor in river design) and the extent of the impact because the change of the channel width affects the flow.

• 한국HCI학회:학술대회논문집
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• 2007.02b
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• pp.55-62
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• 2007

정보통신 기술과 컴퓨터의 급속한 발달은 과거에 불가능했던 많은 일들을 가능하게 하였다. 디지털 기술의 발전은 기존의 추상적인 것을 구체적으로 체험 가능한 것으로 발전시켰으며, 이를 통해 인간은 경험을 확장 시킬 수 있게 되었다. 즉, 인간의 체험, 인식, 가치, 행위가 가상의 공간으로 무한하게 확장될 수 있기 때문이다. 이러한 배경 속에서 현대 사람들은 체험 공간이 현실 세계와는 다른 비일상적 체험과 욕구실현을 구현할 수 있는 공간이 되기를 원한다. 이에 따라서 체험 공간의 논의가 과거의 시각적 정보전달만을 위한 체험 공간이 아닌 정보와 흥미, 체험을 동시에 줄 수 있는 노력들이 요구, 진행되고 있다. 체험 공간에 있어서 엔터테인먼트 적인 요소가 효과적인 방법론으로 제시되고 있지만, 아직도 시청각적 흥미위주의 직선적인 공간의 이야기로 관람자를 일회적인 관람에서 그치게 하고 있다. 매체를 나열식으로 던져 준다고 해서 사람들이 흥미를 느끼거나 몰입을 경험하지는 못한다. 그러기 위해선 인터렉티브 스토리텔링(Interactive Storytelling)의 인터렉티비티한 요소가 체험 공간에서 효과적일 수 있다. 인터렉티비티는 인터렉티브 스토리텔링의 특징 중 하나로, 이와 같은 인터렉티비티 요소들은 관람자에게 다양한 선택과 통제의 기회를 주기 때문이다. 이에 따라서 체험 공간 속에서 관람자는 스스로 매체와 매체간의 반복과 조합을 통해 관람자 개개인이 새로운 시나리오를 쓸 수 있게 되고 체험 공간은 유동적인 공간이 될 수 있게 된다. 따라서 본 연구는 체험 공간이 관람자 스스로가 만들어가는 공간이 되고, 지각적 체험과 정신적 체험까지 경험할 수 있는 체험의 장이 될 수 있도록 인터렉티브 스토리텔링의 가치를 재해석하고자 하였다. 이러한 인터렉티브 스토리텔링이 공간 속에서 의미를 획득할 수 있는지에 대한 연구를 진행하고자 하였으며, 이를 위해 기존의 체험 공간에 대한 연구와 인터렉티브 스토리텔링의 기존 사례를 선행하였다. 이러한 과정을 통해 인터렉티브 스토리텔링이 체험 공간 안에서 사람들에게 일회적인 경험을 주는 것이 아닌 사람들이 직접 그 공간의 스토리를 만들 수 있는 새로운 체험 공간의 가능성을 가지고 있음을 발견하였다. 이에 따라서 월드컵이 열리는 대표적인 도시인 상암동에 한국 소프트웨어진흥원이 주관하여 건설되는 ‘상암 디지털 파빌리온’을 대상으로 인터렉티브 스토리텔링을 기반으로 한 체험공간 디자인을 작품 형태로 기획 되었으며, 기본적인 시나리오 컨셉을 제시하고 공간의 구조도, 체험 과정(Process)등이 제시된다. 이러한 연구는 기존 체험 공간이 직선적인 내러티브에서 벗어나 체험 공간 속 협업의 가능성을 열어주어 새로운 소통의 장을 마련해 준다는 긍정적인 효과를 기대할 수 있다.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.499-506
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• 2005

지반오염조사에 대한 유전상수 측정기법의 적용성을 평가하기 위하여 중금속 오염도에 따른 흙의 유전특성 변화를 분석하였다. 유전상수의 실수부와 허수부 모두 체적함수비에 따른 증가경향을 나타내었으며, 특히 MHz 범위에서 유전상수 실수부는 쌍극자모멘트에 비례하기 때문에 흙의 유전상수는 체적함수비에 따른 선형적인 증가경향을 나타내었다. 중금속 용액은 50kHz 이하의 저주파영역에서 전극 분극효과에 의해 농도 증가에 따라 유전상수 실수부가 증가하는 경향을 나타내었으나, 고주파 영역에서는 이온의 수화작용에 의한 물분자의 배향분극 발현 감소로 인하여 유전상수 실수부가 감소하였다. 유전상수 허수부의 경우에는 모든 주파수 영역에서 중금속 농도 증가에 따른 전도손실에 의하여 증가하는 경향을 나타내었다. 흙과 중금속 혼합시료의 경우 함수비가 큰 시료에서는 중금속 용액 자체의 유전특성이 그대로 발현되었으나, 함수비가 작은 시료에서는 공간전하분극의 영향이 우세하여 유전상수 실수부가 10-20%정도 증가하는 경향을 나타내었다. 유전상수 허수부의 경우에는 중금속 농도 증가에 따른 뚜렷한 증가경향을 확인할 수 있었다. 본 연구의 결과에 의하면 중금속의 오염감지에 대해서는 유전상수 실수부보다는 허수부의 적용성이 높은 것으로 나타났으며, 현장에서의 정확한 오염도 평가를 위해서는 함수비에 대한 평가가 선행되어야 할 것으로 판단된다.

• Journal of the Korea Convergence Society
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• v.10 no.12
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• pp.29-34
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• 2019

If it takes much time to calculate the fitness of the solution in genetic algorithms, it is essential to create a metamodel. Much research has been completed to improve the performance of metamodels. In this study, we tried to get a better performance of metamotel using discrete Walsh transform in discrete domain. We transforms the basis of the solution and creates a metamodel using the transformed solution. We experimented with NK-landscape, a representative function of the pseudo-boolean function, and provided empirical evidence on the performance of the proposed model. When we performed the genetic algorithm using the proposed model, we confirmed that the genetic algorithm found a better solution. In particular, our metamodel showed better performance than that using the radial basis function network that modified the similarity function for the discrete domain.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.6
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• pp.451-462
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• 2011

The smoke control system plays the most important role in securing evacuation environment when a fire occurs in road tunnels. Smoke control methods in road tunnels are classified into two categories which are longitudinal ventilation system and transverse ventilation system. In this study it is intended to review the characteristics of smoke behavior by performing numerical analysis for calculating the optimal smoke exhaust air volume with scaled-model and simulation when a fire occurs in tunnels in which transverse ventilation is applied, and for obtaining the basic data required for the design of smoke exhaust systems by deriving optimal smoke exhaust operational conditions for various conditions. As a result of this study, when the critical velocity in the tunnel is 1.75 m/s and 2.5 m/s, the optimal smoke exhaust air volume has to be more than $173m^3/s$, $236m^3/s$ for the distance of the smoke moving which can limit the distance to 250 m. In addition, in case of uniform exhaust the generated smoke is effectively taken away if the two exhaust holes near the fire region are opened at the same time.

• Fire Science and Engineering
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• v.25 no.3
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• pp.85-90
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• 2011

This study of the vestibule of pressurizing smoke control system installed in domestic high-rise buildings for evacuation in case of fire, when the door is open to forming characteristics of the air flow was analyzed using fire dynamics simulator and analyzed of variance. Vestibule which is compartment of the design condition, air flow in the exhaust damper was formed severe turbulence confirming preceding research. The door position is in the range of formed vortex, unsteady flow of air occurs at the point that the door could be confirmed. According to the NFSC 501A, door to symmetrically separate the average of 10 points or more as measured from the average of wind speed to do is based. Under these conditions, it is difficult to measure the characteristics of the upper air flow of upper points. so measuring points are subdivided by more than 64 points method presented in TAB because severe deviation of wind speed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7118-7125
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• 2015

This study examined one of the concerned or even imperative issues in the field of contemporary finance related to approaching an optimal level of cash holdings for the firms belonging to the chaebols in the Korean domestic capital markets. However, the subject may not have been drawn much attention so far, even if there are still ongoing and active debates among the interest parties at the macro- or micro-level. Two primary hypotheses were postulated to be empirically tested. On the results of the first hypothesis test for the existence of an optimal cash reserves for the sample firms, two estimation techniques were performed in terms of a quadratic regression equation and a relationship between a firm's value and the residuals derived from the static panel date model. As a primary financial implication of the study which may contribute to the practitioners and the academics in finance, the optimal level of cash holdings can be estimated by controlling for the a priori significant components for the sample firms towards maximizing firm value.

• Fire Science and Engineering
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• v.31 no.2
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• pp.44-51
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• 2017

Accurate predictions of the activation time for smoke detectors using a fire simulation is are required to ensure the reliability of the RSET (Required Safe Egress Time) calculation in the process of PBD (Performance-Based Design). The objective of this study was to enhance the accuracy of input parameters for the numerical models of smoke detector based on the FDS. To this end, a Fire Detector Evaluator (FDE) developed in previous studies was improved. The uniformities of flow and smoke inside the FDE were improved and accurate measurements of the obscuration per meter (OPM) related to detector operation were also performed through a decrease in the forward scattering of smoke particles. The input parameters using the improved FDE showed a significant difference from the previous FDE quantitatively. In particular, a larger difference was found in a photoelectric detector compared to an ionization detector. Considering that the operating conditions of smoke detectors are affected by the detector type, combustibles, smoke particulars, and color, the database (DB) on the input parameters for various detectors and combustibles should be built to improve the reliability of PBD in future studies.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.8
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• pp.747-757
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• 2010

The ice accreted on the airfoil is one of the critical drivers that causes the degradation of aerodynamic performance as well as aircraft accidents. Hence, an efficient numerical code to predict the accreted ice shape is crucial for the successful design of de-icing and anti-icing devices. To this end, a numerical code has been developed for the prediction of glaze ice accretion shape on 2D airfoil. Constant Source-Doublet method is used for the purpose of computational efficiency and heat transfer in the icing process is accounted for by Messinger model. The computational results are thoroughly compared against available experiments and other computation codes such as LEWICE and TRAJICE. The direction and thickness of ice horn are shown to yield similar results compared to the experiments and other codes. In addition, the effects of various parameters - temperature, free-stream velocity, liquid water contents, and droplet diameter - on the ice shape are systematically analyzed through parametric studies.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.3
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• pp.230-240
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• 2009

The ESCORT model is applied at Mokpo coastal zone to analyze the effect of fresh water discharge released from the gates of the Youngsan River sea-dyke. Applicability and validity of both 2-D and 3-D hydrodynamic modules could be guaranteed by simulating hydrodynamic feature with ebb dominance characteristics. Then, effects of the released discharge on the hydrodynamics are investigated. And analysis of the effects on diffusion phenomena show that 3-D model is essential for such diffusion modelling. Moreover, vertical salinity distributions near the gates are examined, and the influence range of fresh water is also estimated, which shows that dilution of fresh water is going on slowly because of poor flushing.