• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.676-681
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• 2001

We usually divide the noise of exhaust system into pulsation noise and flow noise. Pulsation noise is the shock wave to occur when the burning gas of low pressure emits and include harmonic having basic frequency as the exhaust cycle of engine. Flow noise is the noise that is produced when gas flow emits into the atmosphere through the pipe and has the character of frequency like pink noise which has the high level of high frequency component. A muffler is divided into reflective type and absorptive type. We usually use the muffler compounding the property of them. In this study, it is the case of transfer matrix method that a muffler is compounded to analyze the elements of each section according to sound wave's proceed direction. But we use simple model. So, we use finite element method that takes short time to analyze. Acoustic analysis gives us transfer matrix to use FEA of SYSNOISE and we use STAR-CD for fluid analysis. We made database that is based on analytical results about the muffler of expansion type, extended type, offset type, reverse type, and perforated type and developed the muffler design system to perform work efficiently.

• 아태비즈니스연구
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• 제14권1호
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• pp.113-129
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• 2023

Purpose - The purpose of this study is to examine whether trading volume amplifies the extent to which lottery-type stocks are overpriced, and whether economic sentiment index explains time-variation in the magnitude of the volume amplification effect. Design/methodology/approach - We examine monthly returns on 5x5 monthly bivariate portfolios formed by lottery characteristics (measured by maximum daily return) and trading volume. In addition, we perform time-series regression tests to examine how the volume amplification effect changes in high and low economic sentiment periods, after controlling for Fama-French three factors. Findings - Our bivariate portfolio analysis shows that the overpricing of lottery-type stocks are mostly pronounced among high trading volume stocks. In contrast, for low trading volume stocks, overpricing of lottery-type stocks appears to vanish. Furthermore, the amplification effect of trading volume on overpricing of lottery-type stock is concentrated in high economic sentiment periods. Research implications or Originality - This study is the first attempt to examine whether trading volume drives lottery-type stocks' overpricing in the Korean stock market. Furthermore, our analysis unveils the time-varying nature of volume amplification effect. The results suggest that trading volume might play a important hidden role in asset pricing, opening a new line of researches in the future.

• 한국융합학회논문지
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• 제10권9호
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• pp.265-272
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• 2019

본 연구는 우리가 일상에서 생각하는 '빈곤'은 과연 무엇인가에서 출발하였다. 특히 본 연구는 개인적인 주관적 의견을 살펴보기 위하여 주관성연구방법인 'Q방법'을 활용하여 빈곤에 대한 인식을 유형화하였다. 분석결과 다음과 같이 4개의 유형으로 정의되었다. 은 "Retraction type"으로, 빈곤이란 'Retraction', 'Individual Effort Problem', 'Social Structure Problem', 'low status', 'Laziness' 등으로 '되물림의 문제'임을 강조하였다. 는 'Individual Effort Problem', 'Laziness', 'Incompetence', 'starvation' 등을 강조하고 있어, "Individual Problem type"으로 명명하였다. 은 'The food and shelter problem', 'starvation', 'Laziness', 'No Money' 등의 삶의 기본적인 요소인 의식주문제를 강조하고 있어, "Basic Problem type"으로 명명하였다. 는 "Resource Distribution Problem type"으로 사회의 구조적인 문제에 따른 '자원분배의 문제'를 강조하고 있는 것으로 나타났다. 본 연구는 주관성연구방법을 활용하여 21세기 빈곤에 대한 인식을 유형화하였으며, 이에 대한 일반화를 위해서 향후 본 연구에서 출발하여 실증연구로의 융합적 확장연구를 기대한다.

• 한국안전학회지
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• 제32권5호
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• pp.96-102
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• 2017

The highest fatal accident ratio was recorded in the construction industry. According to the industrial insurance premium rate & business type example, among the construction industry, the architectural work has the highest fatal and loss time accident ratio. Previous literature has investigated various aspects of accident occurrence and prevention in architectural work. However, those studied were limited in that they only focused on the fatal accident without considering the loss time accident. But non fatal accidents were recorded more than 50 times of fatal accidents. Therefore non fatal accidents must be controlled to lessen industrial accidents. Based on this, the goal of this study was to investigate the nature of the loss time accident and derive the risk index of work type in architectural work. In this study, opinions of safety experts were gathered and the risk index of work type was derived using AHP(Analytic Hierarchy Process). And verification was accomplished by comparing the results of this study with the risk index derived by analysis of accident records. Results showed that the risk index of work type was significantly higher in steel frame work, temporary installation work, earth & foundation work, facilities work, concrete work. And statistical analysis for verification showed that coefficient of Pearson correlation was 0.686 and P-value was 0.001.

• 드라이브 ㆍ 컨트롤
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• 제11권4호
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• pp.46-52
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• 2014

This study suggests a small-sized screw decanter specialized for dredging sites. Generally, conventional screw decanters are composed of a cylinder and a cone. However, the suggested screw decanter simply has a cone based on a cone-type bowl structure. In this research, a commercial analysis tool is used to establish an optimal design for the bowl and the screw conveyor. Moreover, the base frame, where the main bearings that support the spindle of the bowl and the screw conveyor are installed, is optimally designed considering the weight of the rotating body and the deflection caused by the high centrifugal force. Furthermore, the natural frequency range of the spinning body, the bowl and the screw conveyor, is applied to this base frame; it is designed not to correspond to the resonance frequency range and achieves stability as a result. This study suggests an optimal design for the rotating body and the base frame of a screw decanter considering its vibration characteristics. Such a design will prevent overuse of materials and help to reduce the weight and volume-and the price-of a screw decanter.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1279-1288
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• 2019

The vortex-type fluidic diode (FD) is a key safety component for inherent safety in various advanced reactors such as the sodium fast reactor (SFR) and the molten salt reactor (MSR). In this study, topology optimization is conducted to optimize the design of the vortex-type fluidic diode. The optimization domain is simplified to 2-dimensional geometry for a tangential port and chamber. As a result, a design with a circular chamber and a restrictor at the tangential port is obtained. To verify the new design, experimental study and computational fluid dynamics (CFD) analysis were conducted for inlet Reynolds numbers between 2000 and 6000. However, the results show that the performance of the new design is no better than the original reference design. To analyze the cause of this result, detailed analysis is performed on the velocity and pressure field using flow visualization experiments and 3-D CFD analysis. The results show that the discrepancy between the optimization results in 2-D and the experimental results in 3-D originated from exclusion of an important pressure loss contributor in the optimization process. This study also concludes that the junction design of the axial port and chamber offers potential for improvement of fluidic diode performance.

• 국토계획
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• 제54권1호
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• pp.40-51
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• 2019

The ultimate aim of this study is to diagnose the process stage and look at the step change of transition process to see how the step changes. Therefore, in this study, cluster analysis was conducted by examining four types of commercial characteristics such as Retail Homogeneity, Share of Neighbourhood store, Share of chain store, and Share of cafe & Western food store. Through the cluster analysis, three types have been identified. Type1 is the first step which can explain the time before gentrification occurs and when the ratio of neighborhood facilities is the highest. Type2 is the second step that can explain boutique stage where the gentrification occurs. At this time, the ratio of Cafes & Western food restaurant increased and the proportion of neighborhood shops decreased. And Type3, third step is when the mature gentrification occurs. In the analysis of the transition period, it is necessary to monitor the change of the industry in the period from the first stage to the second stage. In the transition period from the second stage to the third stage, It is necessary to constantly monitor such factors as the increase of shops.

• 국토계획
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• 제54권5호
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• pp.76-90
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• 2019

The purpose of this study is to analyze the survival characteristics of the restaurant business by trade area type (major and side street). By the increase of the unemployment rate, the new foundation of selt-employment type is increasing. However, due to high competition and economic recession, the sustainability of new foundation is not high. Therefore, in this study, survival analysis was performed considering the individual and commercial characteristics focused on the ordinary restaurants. The major findings are as follow. First, the characteristics of parcel unit and adjacent area have a significant effect on the survival. This means the micro-scopic spatial characteristics should be considered for survival in the location choice. Second, the regional economic characteristics in trade area have a significant effect on survival. Furthermore, these characteristics are different by the trade area type. Third. the development characteristics have a different effect on survival by the building usage and trade area type. Finally, regional economic characteristics have a significant effect on survival. These results are expected to be used as basic data for commercial location selection and trade area analysis system in the private and public sectors.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.215-220
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• 2002

This paper describes a simulation model for estimation the performance of the swash plate type compressor for automotive air conditioning system. The model includes consideration of both the compression process and the dynamic behavior. Also, this study compares the results obtained from the performance simulation with experimental results. Further, the effects of the inclined angle of swash plate on the performance of swash plate type compressor are discussed.

• 한국경영과학회지
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• 제13권1호
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• pp.1-9
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• 1988

The purpose of this paper is study the sensitivity analysis of matrix game. Teh sensitivity analysis of matrix is classified into two types. Type one is to find the characteristic region of an element of the pay off matrix in which the value of the current optimal strategy remains as an optimum. Type two is to find that in which the basis of the current optimal strategy does not change. This paper shows the characteristic regions of basic and nonbasic strategies. Further it is found that the characteristic regions of type one and two are same in the case that the element is that of at least one player's nonbasic strategy.