• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1530-1535
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• 2003

The utilization of unused energy is important because it can afford to offer a chance to increase energy efficiency of a heat pump system. One of the promising unused energy sources is river water. It can be used as a heat source in both heating and cooling effectively with its superior features as a secondary working fluids. In this study, the performance of a 5HP heat pump system using river water as a heat source is investigated by both experiment and simulation. According to system simulation results, performance improvement of condenser seems more effective than that of evaporator for better $COP_H$. The serial connection is also preferred among several methods to improve plate type heat exchanger performance. The experimental results show that the hot water of $50{\sim}60^{\circ}C$ can be acquired from water heat source of $5{\sim}9^{\circ}C$ with $COP_H$ of $2.7{\sim}3.5$.

• Asian Pacific Journal of Cancer Prevention
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• 제13권4호
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• pp.1159-1166
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• 2012

Research on radiation oncologists has indicated that there is a shortage in supply of specialist workers in this field internationally, and also within Australia. However, there are no current estimates as to what the future Australian radiotherapy workforce will look like. This paper aims to review the current status and capacity of the three main disciplines that make up the radiation oncology workforce in Australia and project the workforce supply and demand for 2014 and 2019. Using data on the workforce from a survey of all radiotherapy facilities operating in Australia in 2008 a workforce model was constructed. This study found that there will be a future shortfall of radiation oncologists, radiation therapists and radiation oncology medical physicists working in radiation oncology treatment. By 2014 there will be 109 fewer radiation oncologists than what will be demanded, and by 2019 this figure will increase to a shortfall of 155 radiation oncologists. There was a projected shortfall of 612 radiation therapists by 2014, with this figure slightly decreasing to a shortfall of 593 radiation therapists in 2019. In 2014, there was projected to be a deficit of 104 radiation oncology medical physicists with a persisting shortfall of 78 in 2019. This future projected shortage highlights the need for radiation oncology workforce planning.

• 설비공학논문집
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• 제13권1호
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• pp.48-58
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• 2001

For the past few decades the vapor compression cycle with a solution circuit (VCCSC) has been known to provide high efficiency and variable capacity. In this study performance of a VCCSC cycle is examined through computer simulation. In the simulation heat exchangers were modelled by specifying UA or effectiveness values while the compressor performance was specified by an isentropic efficiency. Aqua/ammonia solution was chosen as the working fluid which can be used in the high temperature range. The results show that there exists an optimum operation condition which is dependent upon the temperatures of the external heat transfer fluids(HTFs). Besides the HTF\`s temperature, the maximum system pressure and the size of the solution heat exchanger are shown to have an influence on the optimum operation condition. Finally, as compared to a simple vapor compression heat pump with HFC134a, the COP of the VCCSC is shown to be 2∼22% higher.

• 에너지공학
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• 제5권1호
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• pp.19-27
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• 1996

극저온 물질의 저장용기가 외부로부터 일정한 열유속을 받을 때 저장용기내의 압력상승을 해석하였다. 저장용기는 원통형 축대칭이고 윗벽과 아래벽은 단열되었으며 열유속은 옆벽에서 받는다. 유한차분법을 이용하여 저장용기내의 자연대류현상을 해석하였으며, 대상물질로는 산소, 수소 및 질소를 대상으로 하였다. 액체는 비압축성 유체, 기체는 virial 상태방정식을 만족하는 것으로 가정하였다. 기체의 2차 virial 계수는 Lennard-Jones 모형으로부터 구했다. 저장용기내의 압력상승에 미치는 주요한 인자는 외부열유속과 저장용기벽의 열용량 그리고 기체의 초기 부피비였으며, 이들중 가장 중요한 변수는 외부열유속이었다. 산소에 대해 기체를 이상기체를 가정했을 때와 virial 상태방정식을 만족하는 기체로 가정했을 때의 압력차이를 비교했다.

• 동력기계공학회지
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• 제18권5호
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• pp.88-93
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• 2014

In this paper, the performance analysis of condensation and evaporation capacity, turbine work and efficiency of the OTEC power system using vapor-liquid Ejector is presented to offer the basic design data for the operating parameters of the system. The working fluid used in this system is $CO_2$. The operating parameters considered in this study include the vapor quality at heat exchanger outlet, pressure ratio of ejector and inlet pressure of low turbine, mass flow ratio of separator at condenser outlet. The main results were summarized as follows. The efficiency of the OTEC power cycle has an enormous effect on the mass flow ratio of separator at condenser outlet. With a thorough grasp of these effects, it is possible to design the OTEC power cycle proposed in this study.

• 전자공학회논문지A
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• 제32A권3호
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• pp.89-99
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• 1995

In this paper, we ecamined the effect that MCM-L technique influencess on the design and fabrication of multichip memory modules in increasing the packing desity of memory capacity and maximizing its electrical characteristics. For that purpose, we examined the effective methods of reducing the area of module layout and the wiring length with the variation of chip allocation and the number of wiring layers. We fabricated a 256K${\times}$8bit SRAM module with eight 32K${\times}$8bit SRAM chips. The routing experiment showed that we could optimize the area of module layout and wiring length by placing chips in a row, arranging module I/O pads parallel to chip I/O pads, and equalizing the number of terminal sides of module I/O's to that of chip I/O's. The routing was optimized when we used three wire layers in case of one sided chip mounting or five wire layers in case of double sided chip mounting. The fabricated modules showed 18.9 cm/cm$^{2}$ in wiring density, 65 % in substrate occupancy efficiency, and module substrate and functionally tested to find out the module working perfectly.

• 대한기계학회논문집B
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• 제25권11호
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• pp.1492-1499
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• 2001

In order to develop the compact and flexible heat exchangers, we made the helically coiled heat exchangers. They can be manufactured with small diameter copper tubes without the need for fins; inner diameter=1.0 mm, straight tube length=1.5 m. The experiments were carried out with the following conditions; evaporation pressure=0.6 MPa, air velocity=0.7 ∼ 1.7 m/s, and working fluid=R-22. Pressure drop and heat transfer coefficient of heat exchangers were experimented according to the air velocity. The results of heat transfer coefficient show a 35% beneficial increase fur these heat exchangers over the other covered fin-tube heat exchangers. A cooling capacity of about 3 kW was obtained with an air velocity of 1.5 m/s. The distribution header has also been designed fur efficient distribution of refrigerant flow.

• 대한기계학회논문집B
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• 제32권4호
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• pp.255-265
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• 2008

This paper presents the optimization process of evaporator for a vapor compression cooling system for high heat flux CPU. The CPU thermal capacity was given by 300W. Evaporating temperature and mass flow rate were $18^{\circ}C$ and 0.00182kg/s respectively. R134a was used as a working fluid. Channel width(CW) and height(CH) were selected as design factors. And thermal resistance, surface temperature of CPU, degree of superheat, and pressure drop were taken as objective responses. Fractional factorial DOE was used in screening phase and RSM(Response Surface Method) was used in optimization phase. As a result, CW of 2.5mm, CH of 2.5mm, and CL of 484mm were taken as an optimum geometry. Surface temperature of CPU and thermal resistance were $33^{\circ}C\;and\;0.0502^{\circ}C/W$ respectively. Thermal resistance of evaporator designed in this study was significantly lower than that of other cooling systems such as water cooling system and thermosyphon system. It was found that the evaporator considered in this work can be a excellent candidate for a high heat flux CPU cooling system.

• 성인간호학회지
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• 제20권2호
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• pp.296-310
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• 2008

Purpose: The purpose of this study was to compare the importance and performance of nursing interventions linked to five nursing diagnoses in CVA patients. Methods: First, total 37 nursing diagnoses were identified from the analysis of 78 nursing records of CVA patients, and then top 5 diagnoses were mapped with nursing interventions. Second, each intervention was compared in terms of importance and performance by 80 nurses working at neurosurgical units from 5 general hospitals. Data were analyzed using mean, SD, and t-test using the SPSS program. Results: Selected the top five nursing diagnoses were Acute Pain, Risk for Disuse Syndrome, Decreased Intracranial Adaptive Capacity, Ineffective Cerebral Tissue Perfusion and Acute Confusion. In general, most of the interventions were scored higher in importance than performance and most of independent interventions were not performed as frequently as it perceived in importance. The interventions which scored high in performance were the interventions ordered by physician or interventions related to medication behavior. Conclusion: We identified which nursing interventions should be performed more frequently and more critically important to nursing diagnoses. We recommend further research that enhances the performance of nursing interventions to provide better quality of nursing services to the patients in practice.

• 대한기계학회논문집A
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• 제20권1호
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• pp.14-23
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• 1996

Scheduling jobs effectively under consideration of actual loads on machines is one of the most complicated tasks in production control. The complexity of the finite capacity scheduling often makes the conventional methods of industrial engineering fail. As an alternative, Knowledge-based approaches to job-shop scheduling have been evolved recently. This paper presents a blackboard- based scheduling expert system which combines knowledge-based scheduling with interactive scheduling. It is shown to be possible to generate the feasible schedule within a reasonable time. Flexible reaction management is also possible while keeping the changes in the generated schedule to the minimal and adjusting the schedule to tardy operations or working environmental changes. The system is equipped with a rule base with heuristics for handling conflicted event. A case study applying the implemented system is described.