• 한국자동차공학회논문집
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• 제24권6호
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• pp.649-659
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• 2016

This paper describes control algorithm and control structure of vehicle control unit for range-extended electric vehicle equipped with engine-generator system, and specially presents methods which determine optimal operating points and decreases a vibration or a shock for operating the engine-generating system. The vehicle control algorithm is consisted of several parts which are sequence control, calculation of wheel demand torque, determination of operating points, and management of operating points and so vehicle controller has be made possible to efficiently manage calibration parameters. The control algorithm is evaluated by driving test modes, launching performance and operating engine-generator system and so on. In conclusion, this paper present methods for extending a mileage, improving a launching performance and reducing vibration or shock when the engine-generating system is starting or is stopping.

• International Journal of Automotive Technology
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• 제8권3호
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• pp.283-288
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• 2007

This paper presents the static characteristics of a urea-SCR system. The static characterization of the urea-SCR system was generated by sweeping urea flow rates at common engine torque/speed operating points. Several experiments were performed using engine operating points at different raw NOx emission levels, space velocities, and SCR catalyst temperatures. The recorded NOx emissions from the engine exhaust outlet and engine tailpipe are then compared. The urea-SCR static system results indicated that a $50{\sim}60%$ NOx conversion is achievable at most engine operating points using the stoichiometric $NH_3/NOx$ ratio, and a high 98% NOx conversion is possible by exceeding the stoichiometric $NH_3/NOx$ ratio. The effect of the pre-oxidation catalyst volume was also investigated and found to have a profound impact on experimental results, particularly the static NOx conversion.

• 보건의료산업학회지
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• 제8권4호
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• pp.131-140
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• 2014

This study analyzed and compared the oral health care knowledge, oral health behaviors and oral health status of elementary school students in schools with a dental clinic and those without. This study was carried out in November of 2012. The subjects were 188 elementary school students. Structured questionnaires were completed and the SPSS(Ver.17.0) Program was used for the collected data to perform frequency analysis, a t-test, and ANOVA. For oral health knowledge, the operating school dental clinic (OSD) group had a high score of 6.72 points, while the non-operating school dental clinic (NSD) group had 5.95 points. The results were statistically significant(p<0.01). For oral health behavior, the OSD group had a high score of 5.55 points, while the NSD group had 4.59 points, which was statistically significant(p<0.01). Students in schools with school dental clinics have much better knowledge and behavior about oral health than students without school dental clinics.

• 간호행정학회지
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• 제20권3호
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• pp.313-321
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• 2014

Purpose: The purpose was to compare operating room (OR) nurses and general ward nurses on their communication competence and interpersonal relationship ability within the medical team. Methods: Participants were 276 nurses (OR 122, ward 154) working in one of 4 university hospitals located in I and K areas. Data were collected using a questionnaire and data collection was done in June, 2013. Comparisons between OR nurses and general ward nurses on communication competence and interpersonal relationship ability were analyzed using ANCOVA. Results: There were statistically significant differences between the two groups in communication competence (F=11.96, p=.001) with average score for OR nurses at 3.37 points and ward nurses at 3.53 points. There were statistically significant differences between the two groups in interpersonal relationship ability (F=15.51, p<.001) with the average score for OR nurses at 3.30 points and ward nurses at 3.50 points. Conclusion: The results indicate a need to develop a variety of programs to promote communication competence in OR nurses and to enhance the openness of interpersonal relationship ability in human resource management.

• 동력기계공학회지
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• 제12권5호
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• pp.40-47
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• 2008

The turbulent flow characteristics around a small-size axial fan(SSAF) for a refrigerator are strongly dependent upon the operating points. Four operating points such as $\phi$ =0.1, 0.18, 0.25 and 0.32 were adopted in this study to investigate three-dimensional turbulent flow characteristics around the SSAF by using a fiber-optic type Laser Doppler Anemometer(LDA) system. Downstream mean velocity profiles of the SSAF along the radial distance show that axial and tangential velocity components exist predominantly, except $\phi$ = 0.1, and have a maximum value at $r/R{\fallingdotseq}0.8$, but radial velocity component having a relatively small value only turns flow direction to the outside or the central part of the SSAF. The turbulent intensity shows that the radial component exists most greatly after $r/R{\fallingdotseq}0.5$. Downstream turbulent kinetic energy at $\phi$ = 0.25 and 0.32 together has the largest peak value at $r/R{\fallingdotseq}0.9$.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.40.1-40.1
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• 2011

This paper presents a pitch controller which can hold output power constant at the rated value. Although wind turbine contains complicated nonlinearities, its behaviour within a certain operating range of a point can be approximated by that of a linear model. By doing so, we can apply rather simple and systematic linear control techniques such as PID and LQR(Linear Quadratic Regulator) to design a linear pitch controller. Because these linear controllers are valid only in a sufficiently small range around an operating point, linearized wind turbine model under the condition of varying wind speed needs a linear pitch controller can achieve the aims of tracking the rated rotor rotational speed. We propose an improved linear pitch controller taking each merit of LQR and PI controller under the condition of varying operating points in this paper.

• 대한공간정보학회지
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• 제23권2호
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• pp.79-88
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• 2015

측량기준점은 측량을 포함한 지형공간정보의 생산 및 구축과정에 있어서 기본이 되는 매우 중요한 지형공간정보이다. 현재 우리나라의 측량기준점은 국가기준점, 공공기준점, 지적기준점으로 분류되며 생산, 관리, 운영의 주체가 측량기준점의 종류에 따라 다르다. 또한 측량기준점에 대한 일관된 형식 또는 표준이 정의되지 않아 측량기준점에서 제공되는 기본적인 정보가 상이하고, 측량기준점 간의 연계, 통합 활용 및 관리, 운영이 어려운 실정이었다. 따라서 측량기준점의 효율적인 생산, 관리, 운영, 유통을 위한 표준의 제정이 필요하다. 이에 본 연구에서는 측량기준점의 운영현황을 조사하여 표준의 작성을 위한 측량기준점의 대상을 선정하고, 국내 외의 측량기준점의 성과항목을 조사하여 측량기준점의 표준화 항목과 관리 데이터모델을 결정함으로써 기관표준 및 TTA표준을 제정하고 이를 활성화 할 수 있는 방안을 제시하였다.

• 대한전기학회논문지:전력기술부문A
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• 제50권8호
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• pp.388-394
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• 2001

This paper presents how to determine the optimal operating points of Unified Power Flow controllers (UPFC) the line flow control of which can enhance system security level. In order to analyze the effect of these devices on the power system, the decoupled model has been employed as a mathematical model of UPFC for power flow analysis. The security index that indicates the level of congestion of transmission line has been proposed and minimized by iterative method. The sensitivity of objective function for control variables of and UPFC has been derived, and it represents the change in the security index for a given set of changes in real power outputs of UPFC. The proposed algorithm with sensitivity analysis gives the optimal set of operating points of multiple UPECs that reduces the index or increases the security margin and Marquart method has been adopted as an optimization method because of stable convergence. The algorithm is verified by the 10-unit 39-bus New England system that includes multiple FACTS devices. The simulation results show that the power flow congestion can be relieved in normal state and the security margin can be guaranteed even in a fault condition by the cooperative operation of multiple UPECs.

• 동력기계공학회지
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• 제20권6호
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• pp.64-70
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• 2016

The unsteady-state, incompressible and three-dimensional large-eddy simulation(LES) was carried out to evaluate the vorticity distribution of a small-size axial fan(SSAF). The X-component vorticity profiles developed around blade tips turn from axial to radial, and diminish the density of distribution according to the increase of static pressure. Otherwise, the Z-component vorticity profiles evenly develop at the region larger than the half radial distance of blade at the operating points of A and B, partly at the trailing-edge region of blade and radially over bellmouth according to the increase of static pressure.

• 대한기계학회논문집B
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• 제33권11호
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• pp.894-899
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• 2009

Aerodynamic power and torque of wind turbine are highly nonlinear and its operation mode depends on control strategies. Therefore, it is essential to define steady-state curves for the purpose of control and operation of wind turbine system. The steady-state curves of wind turbine can be defined by determining its operating points. In this paper, an algorithm to determine operating points of variable-speed variable-pitch wind turbine is presented on the basis of pitch-to-feather control strategy. And this algorithm is applied to obtain steady-state curves for an 1.5MW wind turbine.