• Structural Engineering and Mechanics
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• 제63권6호
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• pp.809-824
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• 2017

The accurate evaluation of wind characteristics and wind-induced structural responses during a typhoon is of significant importance for bridge design and safety assessment. This paper presents an expectation maximization (EM) algorithm-based angular-linear approach for probabilistic modeling of field-measured wind characteristics. The proposed method has been applied to model the wind speed and direction data during typhoons recorded by the structural health monitoring (SHM) system instrumented on the arch Jiubao Bridge located in Hangzhou, China. In the summer of 2015, three typhoons, i.e., Typhoon Chan-hom, Typhoon Soudelor and Typhoon Goni, made landfall in the east of China and then struck the Jiubao Bridge. By analyzing the wind monitoring data such as the wind speed and direction measured by three anemometers during typhoons, the wind characteristics during typhoons are derived, including the average wind speed and direction, turbulence intensity, gust factor, turbulence integral scale, and power spectral density (PSD). An EM algorithm-based angular-linear modeling approach is proposed for modeling the joint distribution of the wind speed and direction. For the marginal distribution of the wind speed, the finite mixture of two-parameter Weibull distribution is employed, and the finite mixture of von Mises distribution is used to represent the wind direction. The parameters of each distribution model are estimated by use of the EM algorithm, and the optimal model is determined by the values of $R^2$ statistic and the Akaike's information criterion (AIC). The results indicate that the stochastic properties of the wind field around the bridge site during typhoons are effectively characterized by the proposed EM algorithm-based angular-linear modeling approach. The formulated joint distribution of the wind speed and direction can serve as a solid foundation for the purpose of accurately evaluating the typhoon-induced fatigue damage of long-span bridges.

• 한국산학기술학회논문지
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• 제12권11호
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• pp.4718-4725
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• 2011

본 연구는 성능 해석을 통하여 1600cc급 흡기매니폴드의 흡기유량 및 분배특성에 대한 연구를 수행하였다. 일차원 엔진 성능해석 프로그램과 3차원 유동해석프로그램을 이용하여 해석을 수행하였다. 흡기 매니폴드의 정상상태 유동해석을 수행한 결과, 일차원 유동해석과 3차원 유동해석의 유량계수 표준편차는 1% 미만으로 우수한 분배특성을 나타내었다. 일차원 해석 결과가 3차원 결과 대비 미소하게 증가된 결과를 보였지만 동등한 유량계수 경향성을 나타냈다. 비정상상태 해석은 분배특성 측면에서 정상상태 해석 결과와 유사한 결과를 보였으며, 정상상태 해석결과를 통한 비정상상태 분배특성의 예측이 가능함을 확인하였다.

• 한국멀티미디어학회논문지
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• 제14권9호
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• pp.1182-1189
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• 2011

본 논문에서는 대상자의 체력상태에 따른 군집과 운동처방 과정 전반을 시각화 하는 방법을 비쥬얼패스맵이라 명명하고, 비쥬얼패스맵을 이용하여 운동처방사의 처방과정을 시각화하는 것을 목표로 한다. 비쥬얼패스맵은 대상자의 체력상태에 따른 군집 분포, 대상자의 현재 상태와 목표 상태, 운동처방에 따라 어떤 군집에 속하게 될지를 보여준다. 그래서 비쥬얼패스맵은 운동처방 안에 따라 현재 상태에서 목표 상태에 이르기까지의 경로를 나타내게 된다. 비쥬얼패스맵에서 대상자의 특성 간 군집을 표현하기 위해 인공신경망 SOM을 이용했고, 일반인 1,500명의 체력검사 결과값, 비만도, 나이 정보를 학습하여 군집형태를 시각화했다. 또한 운동처방사의 운동처방 자료를 이용하여 운동처방 과정을 비쥬얼패스맵으로 시각화했다.

• Journal of the Korean Data and Information Science Society
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• 제16권3호
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• pp.581-589
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• 2005

The purpose of this thesis is to develop and introduce Add-in program which we can systematically, visually and dynamically study discrete probability distribution of binomial distribution, poisson distribution and hypergeometric distribution, and continuous probability distribution of normal distribution, exponential distribution, and the definition and characteristics of t distribution, F distribution and ${\chi}^2$ distribution to be driven from normal distribution, and graphs, the computation process of probability by using VBA which is the device of Excel.

• 산경연구논집
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• 제11권12호
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• pp.17-28
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• 2020

Purpose: The purpose of this study is to confirm the strategic direction of the firm regarding the capabilities of the organization and its employees in order to increase the utilization and business performance of employees by that introduce smart factories in the domestic manufacturing industry. Research design, data, and methodology: This study derived a structured research model to confirm the mediating effect of recognition responses between the quality characteristics of smart factories and dynamic capabilities. For the analysis, a total of 143 valid questionnaires were used for 200 companies that introduced smart factories from domestic SME's. Results: Quality Characteristics of Smart Factory and Dynamic Capabilities had a statistically significant effect on Usefulness. Recognition Response had a statistically mediating on the relationship between quality characteristics of smart factory and business performance. Recognition Response had a statistically significant effect on business performance. Conclusions: It suggests that firms introducing smart factory reflect them in their empowerment strategic because the recognition responses of its employees differ according to the quality characteristics and dynamic capabilities of smart factories. It also means that the information derived from the smart factory system is useful and effective to business performance and employees.

• 대한전기학회논문지:전력기술부문A
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• 제54권5호
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• pp.212-216
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• 2005

This paper describes the application scheme of resistive HTS-FCL(High Temperature Superconducting-Fault Current Limiter) on future new distribution system. Future new distribution system means the power system to which applies the 22.9kV HTS cable with low-voltage and mass-capacity characteristics replacing the 154kv conventional cable in addition to HTS transformer and HTS-FCL. The fault current of future new distribution system will increase greatly because of the inherent characteristics of HTS transformer/cable and applications of distributed generations and spot networks and so on. This means that the HTS-FCL is necessary to reduce the fault current below the breaking capacity. This paper studies the appropriate location, parameters and the influences of HTS-FCL on future new distribution system. Finally, this paper suggests the reasonable basic parameters of resistive HTS-FCL for future KEPCO new distribution system.

• 통상정보연구
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• 제10권4호
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• pp.321-350
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• 2008

The China has opened the distribution market completely since it joined the World Trade Organization on Dec 11 2001. The notable features of Chinese distribution market are the transition from the consumers' monolithic demand to diversification for the luxury goods, well-being products. The regional characteristics of consumers are smart, conservative, optimistic and advanced. and the open door policy has prompted the capitalistic economy gradually. We analyzed the Chinese distribution markets and came up with the following strategies. First, we recommend the setting of the key regional market not covering the whole chinese markets. then we can extend the main market step by step. Second, we need to cooperate and advance with the Korean distribution companies which entered into markets already. Third, we need to acquire the competitive and stable distribution channel in China. Fourth, we need to implement the localization strategy in terms of human resources and procurement. Fifth, the consignment management can be another strategy. I hope this research can be a little help to those who wish to expand to the Chinese markets.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권8호
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• pp.3630-3656
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• 2018

Degree distribution can provide basic information for structural characteristics and internal relationship in social network. It is a critical procedure for social network topology analysis. In this paper, based on the mean-field theory, we study a special type of social network with exponential distribution of time intervals. First of all, in order to improve the accuracy of analysis, we propose a spreading coefficient algorithm based on intimate relationship, which determines the number of the joined members through the intimacy among members. Then, simulation show that the degree distribution of follows the power-law distribution and has small-world characteristics. Finally, we compare the performance of our algorithm with the existing algorithms, and find that our algorithm improves the accuracy of degree distribution as well as reducing the time complexity significantly, which can complete 29.04% higher precision and 40.94% lower implementation time.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.723-728
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• 2003

The Ejector is used to get low pressure, and it has been applied to a lot of industry field like the heat engine, the fluid instrument power plant, the food industry, environment industry etc... because there are not any problem even it is mixed with a any kind of liquid, gas, and solid. The flow characteristics in ejector are investigated by PIV and CFD. The experiment using PIV measurement for mixing pipe's flow characteristics acquired velocity distribution, kinetic energy distribution, and whirlpool . (Condition : when mixing pipe's diameter ratio is 1:1.9, and the flux is $Q_{1}=1.136{\imath}/s$, $Q_{2}=1.706{\imath}/s$, $Q_{3}=2.276{\imath}/s$. Based on the PIV and the CFD results, the flow characteristics in ejector are discussed, and it shows the validity of this study.

• 한국기계가공학회지
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• 제16권5호
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• pp.150-156
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• 2017

This study tests the characteristics of heat radiation by applying the pin-height variables to 30-W LED floodlights. The angle of the heat sink enables us to identify the characteristics of the heat radiation based on the temperature distribution. The results of the study are as follows. When the heat sinks are set towards the ground, the heat transfer decreases in speed only to expands the temperature distribution, which adversely affects the characteristics of heat radiation and expands the temperature distribution of PCB with the LED chip. We verify that the characteristics of heat radiation are adversely affected when the height of the cooling pin decreases and the heat radiation area decreases, which impedes the heat transfer and increases the temperature distribution on the heat sink.