• 한국재난정보학회 논문집
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• 제14권4호
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• pp.421-429
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• 2018

연구목적 : 본 연구는 기후변화에 따른 강우량 및 강우패턴을 분석하여 강우시 비탈면 거동을 파악하기 위해 강우사상을 합리적으로 적용하여 절토부 비탈면 안정성해석에 활용하고자 수치해석기법을 이용하여 비탈면 높이별, 강우사상별 침투해석을 실시하여 강우사상 및 강우지속시간에 따른 지하수위 변화를 고려한 비탈면 안정성검토를 실시하였다. 연구결과 : 강우사상(Uniform Rainfall, US Army Corps., Huff 4분위법 중 1/4법 및 4/4법)에 따른 화강풍화토 비탈면의 수치해석결과 비탈면이 높을수록 침투된 강우가 지하수위까지 빠르게 도달하지 못하여 지하수위 상승은 작아지고, 비탈면의 안전율도 작게 분석되었다. 결론 : 초기강우강도가 제일 큰 강우패턴 Case 3조건인 Huff 4분위법 중 1/4법에서 지하수위 상승량이 제일 크게 나타났으며, 안전율은 가장 작게 나타났다.

• 국제학술발표논문집
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• The 7th International Conference on Construction Engineering and Project Management Summit Forum on Sustainable Construction and Management
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• pp.73-79
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• 2017

Rapidly expanding population in the Kingdom of Saudi Arabia has a massive impact to put pressure on the shortage of housing and existing infrastructure. With average population growth rate of 1,9% yearly, the population in Saudi Arabia is projected to increase from 31 million in 2015 to 37 million in 2025. According to the housing ministry, Saudi Arabia needs to provide 3.3 million units to meet the demand in 2025, which is about 300,000 unit a year. In the past 40 years, using the conventional construction method, the Saudi construction industry was only able to build about 150,000 units per year. To meet the demand gap for the housing shortage, a new approach and innovation in construction methods are needed. Industrialized construction as an approach in construction methods has been studied and implemented in some countries that experienced similar corncerns. Industrialized construction can be defined as the implementation of manufacturing methods to construction-related activities to improve quality, reduce cost and project duration. Compared to the conventional construction method, prefabrication as industrialized construction methods has reduced construction labor on-site by 9.5%, construction project duration by 20%, and construction waste by 56%. It improves the quality, durability and cost saving not only for construction project owners, but also construction contractors. This paper discusses the possibility of 'industrialization' of building system in the Kingdom of Saudi Arabia as a solution for the housing shortage. It is an initial part of a study aims to develop a framework to develop industrialized building system in the Kingdom of Saudi Arabia. The is paper based on extensive literature review and case studies.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.559-568
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• 2017

Harmonic/inter-harmonic detection and analysis is an important issue in power system signal processing. This paper proposes a fast algorithm based on matching pursuit (MP) sparse signal decomposition, which can be employed to extract the harmonic or inter-harmonic components of a distorted electric voltage/current signal. In the MP iterations, the method extracts harmonic/inter-harmonic components in order according to the spectrum peak. The Fast Fourier Transform (FFT) and nonlinear optimization techniques are used in the decomposition to realize fast and accurate estimation of the parameters. First, the frequency estimation value corresponding to the maxim spectrum peak in the present residual is obtained, and the phase corresponding to this frequency is searched in discrete sinusoids dictionary. Then the frequency and phase estimations are taken as initial values of the unknown parameters for Nelder-Mead to acquire the optimized parameters. Finally, the duration time of the disturbance is determined by comparing the inner products, and the amplitude is achieved according to the matching expression of the harmonic or inter-harmonic. Simulations and actual signal tests are performed to illustrate the effectiveness and feasibility of the proposed method.

• 대한조선학회논문집
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• 제37권2호
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• pp.77-87
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• 2000

항공기나 헬기에서 투하되어 수면으로 입수하는 경어뢰에 작용하는 충격력은 경어뢰 구성부의 손상을 유발시킬 수 있으므로 투하 속도 및 투하 고도를 제한하는 조건이 된다. 따라서, 투하 조건에 따라 입수 충격을 신뢰성 있게 추정할 필요가 있다. 본 연구에서는 선수부 형상에 대한 함수로 입수 충격을 근사적으로 추정할 수 있는 방법을 제시하고, 그 결과를 수치 해석 결과와 비교하여 타당성을 검증하였다. 본 연구에서 제시된 근사화 방법으로 추정한 입수 충격의 크기나 작용시간은 포텐셜 유동이나 점성 유동 해석에 의한 결과들과 비교적 잘 일치하므로 본 연구 결과는 초기 설계 단계에서 안전 발사 영역을 선정하기 위한 기법으로 유용하게 사용될 수 있다.

• 한국경영과학회지
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• 제30권4호
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• pp.99-115
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• 2005

For an analysis of the performance of a computer system, the minimum cycle time method has been widely used. The minimum cycle time method is a mathematical technique with which we can find the minimum duration time needed to fire all the transitions at least once and coming back to the Initial marking in a timed net. A timed net is a modified version of a Petri net where a transition is associated with a delay time. In the real world, an event is associated with a probability of occurrence. However, a timed net is not equipped with any facility of specifying probability of event occurrence. Therefore, the minimum cycle time method applied on a timed net can easily overlook probabilities of occurrences of events and yield a wrong result. We are proposing 'Timed Net with Probabilities of Choices' where a transition can be associated with both delay time and a probability of occurrence. We also introduce an algorithm for minimum cycle time analysis on a 'Timed Net with Probabilities of Choices'. As an example of application, we are performing an analysis of the location based service system using 'Timed Net with Probabilities of Choices'.

• 대한후두음성언어의학회지
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• 제11권1호
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• pp.32-38
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• 2000

Background and Objectives : Voice therapy has been used as a viable adjuvant to surgery and pharmacological therapy fir the management of voice disorders. The singing voice features a special brand of emotion, intensity, and energy so successful therapeutical approach requires the doctor is able to involve himself into the physical and psychic condition and artistic usage of the voice. The purpose of this study was to evaluate the effect and utility of singing therapy as an initial treatment for classically trained singers with voice disorders. Material and method : Twenty-one male and fifty-five female classic singers with voice disorders were treated with singing therapy. At first, abdominal breathing, resonant phonation, and relaxation method was trained, then after accessing each patient's singing abilities, treatment methods for each specific problems was applied. The results were compared according to age, sex, treatment duration, part, laryngeal pathology, patient subjective evaluation, perceptual evaluation of voice, and maximal phonation time. Results : Patients subjective evaluation, perceptual evaluation, pathologic findings of larynx, maximal phonation time showed superior results after singing therapy. Conclusion : Singing therapy changes the mode of respiration and phonation and enhances the vocal function and improves the laryngeal pathology, The result of this study indicate that singing therapy is an effective treatment method that laryngologists can use for classical singers with voice disorders.

• 한국구조물진단유지관리공학회 논문집
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• 제6권3호
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• pp.139-149
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• 2002

Explicit 직접적분법을 사용하여 충격하중을 받는 박판의 후좌굴거동을 해석할 수 있는 알고리즘을 제안하였다. von Karman의 대변위 판 이론과 Marquerre의 쉘 이론을 이용하여 유도한 직사각형 평판 유한요소는 박판의 초기처짐과 기하학적 비선형 거동을 고려할 수 있다. 중앙차분법을 바탕으로 해석 알고리즘을 개발하였고 이를 프로그램화 시켜, 하중형상과 재하시간이 다른 충격하중에 대하여 박판의 동적 좌굴거동을 해석 하였다. 수치해석 예제를 통하여 Explicit 직접적분법의 특성을 평가하였다.

• 한국축산시설환경학회지
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• 제14권2호
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• pp.97-104
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• 2008

본 연구는 지금까지 활용되었거나 새로이 제안된 액상 첨가제를 돈사에 살포하여 분진 농도의 경시적 변화를 관찰하여 제거 효과에 대해 객관적으로 비교 평가하기 위한 것으로 다음과 같은 결론들을 도출했다. 1. 살포 전 밀폐형 돈사내 분진 농도는 다른 연구자의 결과와 비교시 전반적으로 낮았다. 2. 온도의 경우는 살포 후 24시간까지 돈사 내부와 외부 큰 차이가 없었으나, 상대습도는 살포 후 1시간까지 증가하여 외부와 약 10% 가량의 차이를 보였다. 3. 평가대상 모든 액상 첨가제들의 살포직후 분진 평균 저감율은 살포 전 농도 대비 약 30%로 나타났다(p<0.05). 4. 살포 3시간 이후부터는 콩기름을 제외하고 다른 액상 첨가제들의 분진 농도에 대한 경시적 저감 효과가 관찰되지 않았다. 5. 평가대상 모든 액상 첨가제들 중 콩기름의 살포가 제거 효율성 및 안전성 측면 모두 돈사 분진 제어에 대해 가장 효과적인 첨가제였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.3-46
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• 1999

A new method called SRICOS is proposed to predict the scour depth z versus time t around a cylindrical bridge pier of diameter D founded in clay. The steps involved are ; 1. taking samples at the bridge pier site, 2. testing them in an Erosion Function Apparatus called the EFA to obtain the scour rate z versus the hydraulic shear stress applied $\tau$, 3. predicting the maximum shear stress r max which will be induced around the pier by the water flowing at ν Ο before the scour hole starts to develop, 4. using the measured z versus r curve to obtain the initial scour rate zi corresponding to r max , 5. predicting the maximum depth of scour zmax for the pier, 6. using zi and zmarx to develop the hyperbolic function describing the scour depth z versus time t curve, and 7. reading the z vs. t curve at a time corresponding to the duration of the flood to find the scour depth which will develop around the pier. A new apparatus is developed to measure the z vs t curve of step 2, a series of advanced numerical simulations are performed to develop an equation for the $\tau$ max value of step 3, and a series of flume tests are performed to develop an equation for the zmax value of step 5. The method is evaluated by comparing predictions and measurements in 42 flume experiments.

• 한국항공운항학회지
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• 제19권2호
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• pp.1-9
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• 2011

Several studies on the development for solar powered uninhabited aerial vehicles(UAVs) are under way as the use of the renewable energy becomes more and more important these days. This paper is for the conceptual design by a discrete and iterative method. An initial design point with 1.5 meter wing span is determined in the global design, which deploys the mass and energy balances among each component of UAV including solar cells and airframe. Then, the iteration for subsystems is carried out with the help of Vortex Lattice Method(VLM) to optimize the aircraft configuration and the solar power system. It is demonstrated in simulations that the optimized design increases the flight time from 62 to 120 minutes when the solar power system is installed. Also, the associated dynamic analysis reveals that the designed small aircraft has the acceptable stability and controllability.