• International Journal of Air-Conditioning and Refrigeration
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• 제17권3호
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• pp.107-113
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• 2009

The objective of this study is to investigate performance characteristics of a household refrigerator using a two-stage compression cycle. The performance of the two-stage compression cycle was measured by varying the compressor speed, condensing temperature, and evaporating temperature. The COP of the two-stage compression cycle was analyzed and then compared with that of the single-stage compression cycle. The optimum combination of compressor speeds for a low- and a high-stage was determined. The COP of the two-stage compression cycle using a PTC (parallel two-stage compression) method was 5.85% higher than that of a STC (serial two-stage compression) method at optimum operating conditions.

• International Journal of Precision Engineering and Manufacturing
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• 제8권2호
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• pp.70-74
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• 2007

This paper describes the development of a nano-positioning system for nanoscale science and engineering. Conventional positioning systems, which can be expensive and complicated, require the use of laser interferometers or capacitive transducers to measure nanoscale displacements of the stage. In this study, a new self-displacement sensing (SDS) nano-stage was developed using mechanical magnification of its displacement signal. The SDS nano-stage measured the displacement of its movement using a position-sensitive photodiode (PSPD), a laser source, and a hinge-connected rotating mirror plate. A beam from a laser diode was focused onto the middle of the plate with the rotating mirror. The position variation of the reflected beam from the mirror rotation was then monitored by the PSPD. Finally, the PSPD measured the amplified displacement as opposed to the actual movement of the stage via an optical lever mechanism, providing the ability to more precisely control the nanoscale stage. The displacement amplification process was modeled by structural analysis. The simulation results of the amplification ratio showed that the distance variation between the PSPD and the mirror plate as well as the length L of the mirror plate could be used as the basic design parameters for a SDS nano-stage. The PSPD was originally designed for a total travel range of 30 to 60 mm, and the SDS nano-stage amplified that range by a factor of 15 to 25. Based on these results, a SDS nano-stage was fabricated using principle of displacement amplification.

• 한국안전학회지
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• 제9권4호
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• pp.11-16
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• 1994

Acoustic emission technique is applied to the fatigue crack initiation in a carburized gear tooth. Acoustic emission test performed on carburized gear and three-point bending test equal to carburized gear hardness. The marked acoustic emission are detected at the early stage of crack initiation measured by a crack gauge and the final stage just before the tooth failure. The estimated acoustic emission energy rate are characteristic of the measured acoustic emission.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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• pp.230-234
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• 2009

무대조명의 조도 시뮬레이션을 수행하여 얻은 결과치와 실제로 스튜디오 상에서 설치 후 조도값을 실측한 결과를 비교하여 발생하는 오차에 대하여 비교 연구 하였다.

• Fisheries and Aquatic Sciences
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• 제2권1호
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• pp.78-84
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• 1999

Ultrastructural changes in the cuticle of Paleamon serrifer associated with the intermolt cycle were examined and quantified as changes in the cuticular thickness. The cuticular thickness in each zoea stage increased with time elapsed after molting. The cuticle in the premolt stage was about 1.5 and 3 times thicker than that in the postmolt and intermolt stage, respectively. The cuticle in the premolt stage, including the molting space, was more than 5 times as thick as in the postmolt stage. In addition, newly hatched larvae were individually reared in the laboratory and body length for each specimen was measured frequently until the end of zoea VI. An average increase in body length between one zoea stage and the next is about $10\%$ of the length of the previous stage. Within individual zoea stages, the premolt stage had a body length some 0.3% longer than that of the postmolt stage, indicating a growth rate of about 0.03 mm/d.

• Asian Pacific Journal of Cancer Prevention
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• 제15권13호
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• pp.5283-5286
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• 2014

Stage of cervical cancer may adversely affect the quality of life (QOL) among patients. The objective of this study was to predict the QOL among cervical cancer patients by the stage of their cancer. A cross-sectional study from September 2012 until January 2013 was conducted among cervical cancer patients who completed treatment. All patients completed a interviewer-guided questionnaire comprising four sections: (A) socio-demographic data, (B) medical history, (C) QOL measured by general health status questionnaire (QLQ-30) and (D) cervical cancer specific module CX-24 (EORTC) was used to measured patient's functional, symptom scale and their global health status. Results showed that global health status, emotional functioning and pain score were higher in stage III cervical cancer patients while role functioning was higher in stage I cervical cancer patients. Patients with stage IV cancer have a lower mean score in global health status (adjusted b-22.0, 95 CI% -35.6, -8.49) and emotional functioning (adjusted b -22.5, 95CI% -38.1, -6.69) while stage III had lower mean score in role functioning (adjusted b -14.3, 95CI% -25.4, -3.21) but higher mean score in pain (adjusted b 22.1, 95 CI% 8.56, 35.7). In conclusion, stage III and IV cervical cancers mainly affect the QOL of cervical cancer patients. Focus should be given to these subgroups to help in improving the QOL.

• 설비공학논문집
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• 제18권8호
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• pp.641-648
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• 2006

In this study, a two-stage phase-separate cycle was investigated analytically to improve the performance of the $CO_2$ system in the cooling mode. The simulation results were verified with the measured data. The predictions using the simulation model were consistent with the measured data within ${\pm}20%$ deviations. The performance of the modified $CO_2$ system with the two-stage phase-separated cycle was analyzed with the variations of outdoor temperature and EEV opening. The cooling COP decreased with the increase of compressor frequency. The highest COP was 2.7 at compressor frequencies of 30 Hz and 30 Hz for the first and second compressors, respectively. In addition, the cooling COP increased by 9.3% with an application of optimum control of the first and second-stage EEV openings.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.541-547
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• 2000

Experiments were done for the comparison of performance and flow characteristics between a two stage axial flow fan and a counter-rotating axial flow fm. The fan performance curves were obtained by the Korean Standard Testing Methods for Turbo Fans and Blowers (KS B 6311). The fan flow characteristics were measured using a five-hole probe by the non-nulling method. Each stage of the two stage axial flow fan used for the present study has an eight bladed rotor and thirteen stator blades. The front and the rear rotor of the counter-rotating axial flow fan have eight blades each and are driven by coaxial counter rotating shafts through a gear box located between the rear rotor and the electric motor. Both of the two axial fan configurations use identical rotor blades and the same operating conditions for the one-to-one comparison of the two. Performance characteristics of the two configurations were obtained and compared by varying the blade setting angles and axial gaps between the blade rows. The passage flow fields between the hub and tip of the fans were measured and analyzed for the particular operating conditions of peak efficiency, minimum and maximum pressure coefficients.

• 설비공학논문집
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• 제21권6호
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• pp.333-339
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• 2009

The objective of this study is to predict optimal intermediate pressure of a 2-stage compression heat pump system using river water. To determine the maximum performance of the 2-stage compression heat pump system, the experimental evaluations on the 2-stage compression cycle were carried out under various operating conditions. Electronic expansion valves were applied to control intermediate pressure and superheat. Based on the experimental data, an empirical correlation for predicting optimal intermediate pressure which considering cycle operating parameters was developed. The present correlation was verified by comparing the predicted data with the measured data. The predictions showed a good agreement with the measured data within a relative deviation of ${\pm}4%$ at various operating conditions.

• 대한안전경영과학회지
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• 제13권2호
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• pp.243-249
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• 2011

The purpose of the study was to improve of performance for Magnetic Resonance Imaging (MRI) examination in the department of radiology. It was performed DMAIC (Define, Measure, Analyze, Improve, and Control). In the stage of definition, The fifth kinds of CTQ (critical to quality) by the kindness, the waiting time, the examination explanation, the waiting time and the waiting environment were selected by voice of customer. In the stage of measurement, the performed examinations and the reservation waiting time were measured each 1.77 and 1.69 sigma. In the stage of analysis, the potential key causes were determined the limited working hours and the difference of examination time of various entries. In the stage of improvement, MRI were performed with the operating system of 24 hours examination and the optimization of the difference of examination time by among of 30 minutes, 40 minutes, 50 minutes. Finally, the number of examinations and reserved waiting days were measured by each 3.17 and 1.71 sigma in the control stage.