• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.1
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• pp.1-9
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• 2017

The scale of disaster and damage witnessed in the 2004 Indian Ocean Tsunami and the 2011 Great East Japan Tsunami has motivated researchers in developing foolproof disaster mitigation techniques for safety of coastal communities. This study focuses on developing tsunami hazard map by numerical modeling at Imwon Port to minimize losses of human beings and property damage when a real tsunami event occurs. A hazard map is developed based on inundation maps obtained by numerical modeling of 3 past and 11 virtual tsunami cases. The linear shallow-water equations with manipulation of frequency dispersion and the non-linear shallow-water equations are employed to obtain inundation maps. The inundation map gives the maximum extent of expected flooded area and corresponding inundation depths which helps in identifying vulnerable areas for unexpected tsunami attacks. The information can be used for planning and developing safety zones and evacuation structures to minimize damage in case of real tsunami events.

• Radiation Oncology Journal
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• v.17 no.1
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• pp.78-83
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• 1999

Purpose : We have compared the characteristics of Siemens virtual wedge device with physical wedges for clinical application. Materials and Methods : We investigated the characteristics of virtual and physical wedges for various wedge angles (15, 30, 45, and 60$^{\circ}$) using 6- and 15MV photon beams. Wedge factors were measured in water using an ion chamber for various field sizes and depths. In case of virtual wedge device, as upper jaw moves during irradiation, wedge angles were estimated by accumulated doses. These measurements were performed at off-axis points perpendicular to the beam central axis in water for a 15cm${\times}$20cm radiation field size at the depth of loom. Surface doses without and with virtual or physical wedges were measured using a parallel plate ion chamber at surface. Field size was 15cm H20cm and a polystyrene phantom was used. Results : For various field sizes, virtual and physical wedge factors were changed by maximum 2.1% and 3.9%) , respectively. For various depths, virtual and physical wedge factors were changed by maximum 1.9% and 2.9%, respectively. No major difference was found between the virtual and physical wedge angles and the difference was within 0.5$^{\circ}$ . Suface dose with physical wedge was reduced by maximum 20% (x-ray beam :6 MV, wedge angle:45$^{\circ}$, 550: 80 cm) relative to one with virtual wedge or without wedge. Conclusions : Comparison of the characteristics of Siemens virtual wedge device with physical wedges was performed. Depth dependence of virtual wedge factor was smaller than that of physical wedge factor. Virtual and physical wedge factors were nearly independent of field sizes. The accuracy of virtual and physical wedge angles was excellent. Surface dose was found to be reduced using physical wedge.

• Journal of the Korea Computer Graphics Society
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• v.26 no.5
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• pp.1-13
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• 2020

In this paper, we propose a new method to stable simulation the directional ice shape by coupling of freezing solver and viscous water flow. The proposed ice modeling framework considers viscous fluid flow in the direction of ice growth, which is important in freezing simulation. The water simulation solution uses the method of applying a new viscous technique to the IISPH(Implicit incompressible SPH) simulation, and the ice direction and the glaze effect use the proposed anisotropic freezing solution. The condition in which water particles change state to ice particles is calculated as a function of humidity and new energy with water flow. Humidity approximates a virtual water film on the surface of the object, and fluid flow is incorporated into our anisotropic freezing solution to guide the growth direction of ice. As a result, the results of the glaze and directional freezing simulations are shown stably according to the flow direction of viscous water.

• Progress in Medical Physics
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• v.12 no.2
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• pp.125-131
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• 2001

We was investigate the dosimetric characteristics of the virtual wedge and it compared to the conventional fixed wedge. Also we was evaluate the quality factor of the experimental multi-channel dosimetry system for virtual wedge. Recently virtual wedge technique and wedge fraction methods are available through the computer controlled asymmetric collimator or the independent jaw in medical linear accelerator for radiation therapy. The dosimetric characteristics are interpreted by radiation field analyzer RFA-7 system and PTW-UNIDOS system. Experimental multi-channel dosimetry system for virtual wedge was consists of the electrometer, the solid detector and array phantom. The solid detectors were constructed using commercially diodes for the assessment of quality assurance in radiotherapy. And it was used for the point dose measuring and field size scanning. The semiconductor detector and ion chamber were positioned at a dmax, 5 cm, 10 cm, 20 cm depth and its specific ratio was determined using a scanning data. Wedge angles in fixed and virtual type are compared with measurements in water phantom and it is shown that the wedge angle 15$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$were agree within 1$^{\circ}$ degree in 6, 10 MV photon beams. In PDD and beam flatness, experimental multi-channel disimetry system was capable of reproduceing the measured values usually to within $\pm$2.1% the statistical uncertainties of the data. It was used to describe dosimetric characteristics of virtual wedge in clinical photon beams. Also we was evaluate optimal use of the virtual wedge and improve the quality factor of the experimental multi-channel dosimetry system for virtual wedge.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.3
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• pp.195-203
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• 2002

In the engine room and the aft part areas of the ship, there exist so many tank structures contacting with fresh water or sea water or oil. If these structures exhibit excessive vibrations during the sea trials, it takes a lot of cost, time and effort to improve vibration situation because the reinforcement work requires emptying the fluid out of the tanks, additional welding and special painting. It is therefore very important to predict a precise vibration characteristics of the tank structures at the design stage, however it is not easy to estimate vibration characteristics of the structures because of difficulties for accurate evaluation of the added (or virtual) mass effect due to the fluid inside the tank. In this paper, numerical and experimental approaches have been performed to present same fundamental data necessary for anti-vibration design of tank structures contacting with fluid, by investigating vibration behaviors of rectangular tank structure for various water depths.

• The Journal of the Acoustical Society of Korea
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• v.20 no.4
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• pp.71-80
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• 2001

In order to consider the sediment layer's effect to total acoustic field, we composed a 3 layered fluid model of 2 sediment layers by adding an additional layer to the Pekeris model and found solutions by using Green's function, boundary conditions and Sommerfeld radiation condition. The modes were divided into discrete modes and virtual modes, and confirmed that the characteristic equation to find discrete modes was same as that of Tolstoy and Clay for normal modes. Also, we confirmed that under similar conditions the 3 layered model showed same results as that of Pekeris model. We believe this 3 layered model can be used to study the sediment's effect on the virtual mode of near field.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.6
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• pp.564-573
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• 2012

The objective of this study is to determine the effect for the sound quality according to the noise source and to build the sound quality index of the laundry noise. In order to compare laundry noise among the influence of noise sources, we made virtual laundry noises by synthesizing an actual laundry noise and each noise source such as a dropping noise, water noise, motor noise and circulation pump noise. We conducted a listening test by customers using virtual laundry noises. As a result of listening test, we found that the dropping noise has a decisive effect on the sound quality of the laundry noise. We conducted the multi regression analysis of sound quality for the laundry noise using the statistical data processing. It is verified to the reliability of the multi regression index by comparison with listening results and index results of other actual laundry noises. This study is expected to provide a guide line for improvement of the laundry noise.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.839-843
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• 2004

최근 들어 수자원 계획과 관리에 대한 평가를 위해 수문, 사회, 경제 및 환경 지표들을 이용하여 평가하고자 하는 노력들이 지속되고 있다. 이를 통해 수자원의 여건을 여러 지표들을 통합한 통합지표로 평가함으로서 객관적이고 투명한 결과로 도출하고자 하고 있다. 여러 국제기구 및 연구단체에서는 최근 논의가 되고 있는 지속가능한 발전을 평가하기 위해 각 국가별 자료를 수집하여 지표분석을 통해 각 국가별 상황을 제시하고 있다. 대표적인 통합지표로는 WPI(Water Poverty Index), HDI(Human Development Index)와 ESI(Environmental Sustainability Index) 등이 있으며 이 외에도 OECD, SEI 등과 같은 국제기구들이 여러개별 지표들을 통하여 지속가능성을 평가하고자 하고 있다. 또한 가상의 물 교역(virtual water trade)을 통해 개발된 지표들을 이용하여 각 나라의 수자원 현황을 평가하였다. 본 연구에서는 개발되었던 경제, 사회의 통합지표인 HDI, 환경 통합지표인 ESI, 수자원관련 통합지표인 WPI 등을 소개하고 이를 통해 우리나라의 지속가능성을 평가하여 보았다. 또한 Virtual Water Trade를 통해 국가별 수자원 현황을 평가하였고 여러 개별지표 등을 통해 수자원 뿐만 아니라 경제, 사회, 환경 등 여러분야에 대해 우리나라의 상황을 알아보았다. 이 연구를 통해 정확하게는 분석이 이루어진다고 말할 수는 없지만 정책결정에 도움을 줄 수 있는 정보를 제공하였다고 생각된다. 또한 국내, 외의 여러 지표를 통해 국내 실정에 맞는 우리나라의 수자원을 평가할 수 있는 통합적인 수자원관련 지표 개발에 많은 도움을 주었으리라 사료된다.DEM 자료로 변환하였다. 또한 유역의 고도차를 이용한 흐름특성 분석을 위해 수치고도자료를 이용하여 유역흐름특성을 분석할 수 있는 TOPAZ(Topographic PArameteri-Zation) 프로그램을 이용하였다. TOPAZ 프로그램을 통해 분석된 각 격자별 분포형 수문 매개변수는 적합한 관계식을 통해 분포형 유출량을 모의하는데 적용된다.다 정확한 유입량 예측이 가능할 것으로 사료된다.이 작은 오차를 발생하였으며, 전체적으로 퍼프 모형이 입자모형보다는 훨씬 적은 수의 계산을 통해서도 작은 오차를 나타낼 수 있다는 것을 알 수 있었다. 그러나 Gaussian 분포를 갖는 퍼프모형은 전단흐름에서의 긴 유선형 농도분포를 모의할 수 없었고, 이에 관한 오차는 전단계수가 증가함에 따라 비선형적으로 증가하였다. 향후, 보다 다양한 흐름영역에서 장${\cdot}$단점 분석 및 오차해석을 수행한 후에 각각의 Lagrangian 모형의 장점만을 갖는 모형결합 방법을 제시할 수 있을 것으로 판단된다.mm/$m^{2}$로 감소한 소견을 보였다. 승모판 성형술은 전 승모판엽 탈출증이 있는 두 환아에서 동시에 시행하였다. 수술 후 1년 내 시행한 심초음파에서 모든 환아에서 단지 경등도 이하의 승모판 폐쇄 부전 소견을 보였다. 수술 후 조기 사망은 없었으며, 합병증으로는 유미흉이 한 명에서 있었다. 술 후 10개월째 허혈성 확장성 심근증이 호전되지 않아 Dor 술식을 시행한 후 사망한 예를 제외한 나머지 6명은 특이 증상 없이 정상 생활 중이다 결론: 좌관상동맥 페동맥이상 기시증은 드물기는 하나, 영유아기에 심근경색 및 허혈성 심근증 또는 선천성 승모판 폐쇄 부전등을 초래하는 심각한 선천성 심

• The Journal of the Korea Contents Association
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• v.7 no.3
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• pp.68-78
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• 2007

In a virtual aquarium, the behavior of fish objects is the most important factor in respect of visual effects. In addition to the individual behavior of fish object, the interactions between objects due to their attributes, can improve the dynamics and reality of the virtual world. In this paper, we analyze the principal habits of fish objects such as the vitality, the range of movement, the maximum depth of water they can live, and the cycle of eating. Then, we suggest a method for simulating the stable marine ecosystem with controlling the behaviors, the interaction with other species, the average span of life, and all that sort of thing based on the result of analysis. Because we can freely modify the behavior of fish object by altering the values of attributes, it can be utilized in the dynamic virtual aquarium, the 3D aquarium screen saver, and the virtual fish game, and so on.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.175-178
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• 2000

In this study, the ultrasonic transducer was fabricated with piezoceramic-polymer 1-3 type composites. Pulse-echo response of that transducer in water was investigated with variable water-level. Output of LED was under the control of the signal, which was analyzerd by the self-made Electric Unit. This paper represents automatically water-detecting system with variable water level. There was in good agreement water level between the virtual level and output signal by using the self-made water-detecting system.