• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.1
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• pp.39-46
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• 1994

Experiments on the performance of refrigeration system using alternatives to R12 are carried out. The condenser and the evaporator are concentric-tube heat exchangers of counter-flow type and the compressor is driven by a variable speed motor. In this study, R134a, R152a, R22/142b(50 : 50 by mass) are adopted as alternatives to R12. Tests are performed by varying the inlet and outlet temperatures of secondary fluids of evaporator and condenser under the condition of constant compressor speed, degree of superheating and degree of subcooling. Results show that R134a has refrigeration capacity close to that of R12 and requires the greatest compressor power compared with that of others. And the system using R152a shows the best performance from the viewpoint of refrigeration capacity, compressor power and coefficient of performance. R22/142b is superior to R12 in the above points.

• Journal of the Korean Solar Energy Society
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• v.36 no.2
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• pp.53-63
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• 2016

Building Integrated Photovoltaic (BIPV) is one of the best ways to generate electric power using the solar energy, which is clean and inexhaustible energy resources. The most of BIPV modules have the form of GtoG (Glass to Glass) photovoltaic in building applications. Degradation leading to failure in photovoltaic modules is very important factor in BIPV modules. This paper analyzed the performance of various BIPV modules through outdoor exposure tests. Performance of three BIPV modules(c-Si type, a-Si type and DSSC type) with three installation angles influenced by sun light, outdoor temperature, and wind velocity was monitored and analyzed. As a result, c-Si type BIPV module outperforms other BIPV modules(a-Si type). In terms of power efficiency of the module, the installed angle of $45^{\circ}$ is better than others(90 degree, 0 degree). In addition, more realistic data of various BIPV system performance could be available through the field test and integrated building test. In this study, relationship of the BIPV system is identified module's installation angle, power generation, architectural performance, etc.

• The Journal of Korean Academic Society of Nursing Education
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• v.19 no.4
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• pp.508-517
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• 2013

Purpose: The purpose of this study was to evaluate the effectiveness of infant CPR (Cardiopulmonary Resuscitation) immediate remediation[LAB2]. Methods: This is a quasi-experimental study with a non-equivalent comparison group pre-post test design. Participants were 73 child care teachers in J district in Seoul. The experimental group (35) received immediate remediation with video learning [LAB3]for infant CPR education and the control group (38) received video learning only. We investigated confidence of infant CPR and tested single-rescuer infant CPR performance depending on a checklist (8 items). Data were collected before and right after to evaluate the confidence of infant CPR and before, right after and 2 weeks after the education to evaluate the skill performance and final acceptance. Results: There was a significant increase in confidence of infant CPR in the experimental group and control group. There was a statistically significant difference in the degree of skill performance between groups according to the amount time (F=10.58, p<.001). The degree of skill performance was tested two weeks after the education and immediate remediation was 5.35 times more effective compared to the video image demonstration (B=1.677, p<.001). Conclusion: The findings provide the necessity of immediate remediation education of infant CPR to increase confidence and skill performance ability.

• Journal of Korea Game Society
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• v.10 no.6
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• pp.57-65
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• 2010

In this paper, mobility performance indices are proposed which may be used to estimate characteristics of output velocity space in six-degree-of-freedom parallel mechanism. In order for manipulability and condition number to not suffer from lack of the physical meaning due to dimensional inhomogeneity, output space is partitioned into translational velocity space and rotational velocity space, respectively. In each space, mobility ellipsoids corresponding to unit input space are defined and two types of mobility performance in translational velocity spaces indices are derived. Two types of mobility performance in rotational velocity spaces indices are derived.

• Korean journal of food and cookery science
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• v.14 no.5
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• pp.482-491
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• 1998

The objectives of this study were to characterize the food service managements in university food services. In a survey involving university food service centers throughout the country, the importance, performance scores and policies for food service management were investigated. Of the total 40 institutions surveyed, 23 were run directly by the institution, eight by contract, and nine by rental. Data were analyzed by t-test, ANOVA using the SPSS program. Management system was evaluated separately for organization, human resources, finance, nutrition education, purchasing, quality control, sanitation and safety, and marketing for their relative importance, degree of performance, and policy establishment. It was found that the relative importance scored higher than the degree of performance and policy establishment. When rhe relative importance for the direct, contract and rental operations was compared, the rental operation scored the highest. Performance score of direct was the highest in direct operation. The findings of this research suggest that the university food service should be creative through systematic management, and further research is needed to evaluate various variables that influence productivity, such as employee morale, pleasant working environment, customer satisfaction, and introduction of TOM for university food services.

• Smart Structures and Systems
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• v.1 no.3
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• pp.235-256
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• 2005

The non-linear behaviour of electrorheological (ER) and magnetorheological (MR) dampers makes it difficult to design effective control strategies, and as a consequence a wide range of control systems have been proposed in the literature. These previous studies have not always compared the performance to equivalent passive systems, alternative control designs, or idealised active systems. As a result it is often impossible to compare the performance of different smart damper control strategies. This article provides some insight into the relative performance of two MR damper control strategies: on/off control and feedback linearisation. The performance of both strategies is benchmarked against ideal passive, semi-active and fully active damping. The study relies upon a previously developed model of an MR damper, which in this work is validated experimentally under closed-loop conditions with a broadband mechanical excitation. Two vibration isolation case studies are investigated: a single-degree-of-freedom mass-isolator, and a two-degree-of-freedom system that represents a vehicle suspension system. In both cases, a variety of broadband mechanical excitations are used and the results analysed in the frequency domain. It is shown that although on/off control is more straightforward to implement, its performance is worse than the feedback linearisation strategy, and can be extremely sensitive to the excitation conditions.

• The Journal of Korean Academic Society of Nursing Education
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• v.10 no.1
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• pp.44-53
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• 2004

Purpose: This research was to grasp task performance of the Preceptor and to offer the basic data to a Preceptorship establishment. Method: 208 Preceptors which have been working at three 3rd medical institutions of Seoul. A task performance degree of Preceptor has been measured using a questionnaire which modifying and supplementing Schiwirian's tool(1974) The collected data was analyzed into description statistics, t-test and ANOVA through the SPSSWIN program. Result: The task performance degree was a $4.06{\pm}.51$ score. Personal relations and understanding was the highest area with a $4.31{\pm}.50$ score and patient education was the lowest area with a $3.69{\pm}.58$ score. the service career as a nurse is more than nine years(F=3.122, P=.027), worked as the Preceptor for more than five years to less than a seven year period(F=3.499, P=.016), the number of new nurses to educate as a Preceptor is more than five(F=3.509, P=.009), it has been evaluated as a good task performance. Conclusion: The selection of competent Preceptor and the development of the education program for Preceptors are required to deal with their task effectively. Above all, the task achieved successfully can be contributed to a Preceptorship establishment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.3
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• pp.167-174
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• 2003

Military facilities with masonry have a great portion in the whole military facilities. But lots of them have been used for more than 20 years, the degree of deterioration of the facilities are serious. Futhermore, as insufficient budget for the facilities maintenance and poor maintenance, the performance of the aged masonry facilities have continually decreased. We suggest a structural performance assessment criteria for the military facility through literature review, interview with experts and questionnaire. The major assessment factors for the structural performance include the inclining and sinking degree of the facilities, durability of materials and resisting force of the structural members.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.91-100
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• 2013

This research is to measure and analyze the thermal performance of the apartment structure and to evaluate and establish standards of thermal insulation defect in order to make the basic data necessary for determining the degree of the thermal performance degradation and for repairing and reinforcing the exterior wall of the existing apartment. Furthermore, it is to predict the part of occurrence of the thermal bridge and condensation at the apartment building structure. On the other one hand, it is also to analyze the degree of thermal insulation performance according to the standards of thermal insulation and elapsed time, through the analysis by the workability of concrete.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.585-591
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• 2021

Liquefied hydrogen have advantage which reduces the volume by about 800 times or more compared to hydrogen gas, so it is possible to increase the storage density. However, liquefied hydrogen produced by cryogenic cooling of 20 K or less at normal pressure has a problem of maximizing the insulation effect that blocks heat introduced from the outside. Representative insulation technologies include vacuum insulation and multi-layer insulation materials and in general, heat blocking is attempted by combining insulation technologies. Therefore, in this study, the pressure of the internal vacuum layer was changed to 10^-1, 10^-2, 10^-3 and 10^-4 Torr to confirm the thermal insulation performance of the vacuum jacket valve for transporting liquefied hydrogen. As a result, it was confirmed that the insulation performance improved as the degree of vacuum increased.