• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.199-202
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• 2006

The objective of this study is to propose methods of controlling the wake behind a sphere for drag reduction using the suboptimal control theory and surrogate management framework, respectively. The Reynolds numbers considered is 300 at which the base flow is unsteady planar symmetric. Given the cost function defined as the square of the difference between the target pressure (potential-flow pressure) and real flow pressure on the sphere surface, the suboptimal control makes the flow steady axisymmetric and produces drag reduction. Based on the actuation profile from the suboptimal control, the optimal wavy actuation profile is obtained using the surrogate management framework and produces drag reduction.

• Journal of the Korea Safety Management & Science
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• v.22 no.2
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• pp.15-21
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• 2020

Industrial facilities need design to predict and reduce noise from design to prevent and reduce noise. The purpose of this study is to predict worker's environment and evaluate safety by analyzing noise inside underground blower room and air compressor room with fluid machinery in waste facility. This waste incineration facility was analyzed based on the ground floor, ground floor blower chamber, and air compressor chamber. The results of SPL(Sound Pressure Level) analysis at 1.5m away, which are frequently used to measure the SPL as a noise source, are as follows. SPL of basement level: 46.80[dB], SPL of ground layer: 48.57[dB]. As a result, it was expected that the noise level would be considerably lower than the 8 hours 50[dB] noise exposure per day.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.259-260
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• 2023

최근 고용 시장은 프리랜서 비율 상승과 근무 형태 다양화로 인해 변화하고 있다. 그러나 현재의 업무 관리 서비스는 여러 도구를 사용하는 불편함이 있다. 이 논문은 급여 유동성을 갖는 근무자를 대상으로, 캘린더, 메모 도구, 급여 계산기를 통합한 업무 관리 서비스를 제안한다. 이를 통해 한 플랫폼에서 업무 관리를 수행하고, 급여 계산과 기간별 급여 조회가 가능해진다. 또한 일정 공유, 채팅을 통한 의사소통과 자료 공유로 팀의 성과 향상을 기대할 수 있다. 더 나아가, 서비스의 확장 가능성과 추가 연구의 필요성도 언급하고 있다.

• International Journal of Advanced Culture Technology
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• v.2 no.1
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• pp.1-13
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• 2014

In next-generation wireless networks, provisioning of IP-based network architecture and seamless transmission services are very important issues for mobile nodes. For this reason, a mobility management mechanism to support global roaming is highly regarded. These technologies bring a broader life by using a global roaming account through the connection of multiple devices or technology to mobile users; they also provide real-time multimedia services. This paper presents a comprehensive performance analysis of fast handover for hierarchical mobile IPv6 (F-HMIPv6), hierarchical mobile IPv6 (HMIPv6), Proxy Mobile IPv6 (PMIPv6), and fast Proxy Mobile IPv6 (FPMIPv6) using the fluid-flow model and random-walk model. As a result, the location update cost of the PMIPv6 and FPMIPv6 is better than that of HMIPv6 and F-HMIPv6. These results suggest that the network-based mobility management technology is superior to the hierarchical mobility management technology in the mobility environment.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.41-44
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• 2006

In the field of launch vehicle development, aerodynamic design means an overall management about external appearances. At least, related to outer figures of the launch vehicle, aerodynamic design has the initiative activities. For that reason, in this report, aerodynamic design techniques and application methods will be introduced.

• Journal of Korean Neurosurgical Society
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• v.37 no.1
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• pp.59-62
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• 2005

We describe two cases of tension pneumocephalus, one caused by ventriculoperitoneal shunt for communicating hydrocephalus, and the other caused by craniocerebral trauma. In the first case report, we examined the relationship between cerebrospinal fluid leakage and delayed onset tension pneumocephalus. The second case report, we addressed issues such as the diagnosis, management, and pathogenesis, as well as computerized tomography(CT) findings.

• Communications of the Korean Mathematical Society
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• v.28 no.4
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• pp.851-856
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• 2013

The principal aim of this paper is to investigate a recurrence relation and an integral representation of k-Mittag-Leffler function introduced earlier by Dorrego and Cerutti [2] and several special cases have also been discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.2
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• pp.150-157
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• 2008

The main objective of this paper is to investigate the performance characteristics of a $CO_2$ air conditioning system for fuel cell electric vehicles (FCEV). The present air conditioning system for FCEV uses the electrically driven compressor and electrically controlled expansion valve for $CO_2$ as a working fluid. The experimental work has been done with various operating conditions, which are quite matching the actual vehicle's driving conditions such as different compressor speed and high pressure to identify the characteristics of the system. Experimental results show that the cooling capacity and coefficient of performance (COP) were up to 6.3kW and 2.5, respectively. This paper also deals with the development of optimum high pressure control algorithm for the transcritical $CO_2$ cycle to achieve the maximum COP.

• Korean Journal of Occupational Health Nursing
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• v.10 no.1
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• pp.5-23
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• 2001

The purpose of this study was to analyse the level of recognition and performance of clinical nurses about the prevention of nosocomial infection. Subjects of the study were 425 nurses working at two university hospitals. Self report questionnaires were used to measure the level of recognition and performance about the prevention of nosocomial infection. These instruments had five dimensions of the management of nosocomial infection : hand washing, fluid therapy, foley catheterization, respiratory tract, and aseptic articles. Reliability coefficients of these instruments were found Cronbach's ${\alpha}=.94-.95$. Data were collected from August 1 to August 15, 2000. The results of the study were as follows : 1) The mean score of the recognition scores about the management of nosocomial infection was 3.89. 2) The mean score of the performance about the management of nosocomial infection was 3.42. 3) The mean score of the recognition about the management of nosocomial infection was significantly higher than the performance score(t=25.72. p<.001). 4) There was significant difference in the score of the recognition about managment in nosocomial infection according to nurses working unit(p<.001).

• Journal of Drive and Control
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• v.16 no.2
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• pp.80-90
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• 2019

Fuel cell hybrid electric vehicle is an attractive solution to reduce pollutants, such as noise and carbon dioxide emission. This study presents an approach for energy management and control algorithm based on energetic macroscopic representation for a fuel cell hybrid electric vehicle that is powered by proton exchange membrane fuel cell, battery and supercapacitor. First, the detailed model of the fuel cell hybrid electric vehicle, including fuel cell, battery, supercapacitor, DC-DC converters and powertrain system, are built on the energetic macroscopic representation. Next, the power management strategy was applied to manage the energy among the three power sources. Moreover, the control scheme that was based on back-stepping sliding mode control and inversed-model control techniques were deduced. Simulation tests that used a worldwide harmonized light vehicle test procedure standard driving cycle showed the effectiveness of the proposed control method.