• 소음진동
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• 제10권5호
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• pp.873-879
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• 2000

Experimental investigation was conducted to study the effects of pitch angle maximum camber on the performance and noise of an axial-flow fan used in outdoor-unit of air -conditioner. For this study the axial-flow fan whose pitch angle can be varied was made and the Specific sound Pressure Level and other coefficients were measured using the anechoic fan tester. It is found that pitch angle affects more severly than the maximum camber on the fan performance. On the while the maximum camber affects much on the specific sound power level. Present results show that it is important to choose the optimum pitch angle and maximum camber to design the high-performance and low-noise axial-flow fan and specific noise measured in the anechoic fan tester can be sued effectively for the design of low-noise fan.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.245-246
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• 2011

Emission lines ratios were used for diagnostics of and excited level densities in low-temperature plasmas. In this work, an optical emission spectroscopy (OES) was used to determine the electron temperature and metastable level densities in low-pressure inductively coupled plasma. The emission spectroscopy method was based on a simple collisional-radiative model. The selected lines of the Ar(4p to 4s) were influenced by the radiation trapping at relatively high pressures where the plasma become optically thick. To quantify this effect, a pressure dependence factor ${\alpha}$(P) was derived by using corrections for the measured intensities. It was found that the lower metastable level densities were obtained when ${\alpha}$(P) increased with the increasing discharge pressure. The effect of non-Maxwellian electron energy distribution functions (EEDFs) on the metastables was also presented and discussed.

• 대한간호학회지
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• 제35권1호
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• pp.125-134
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• 2005

Purpose: The purpose of this study was to identify the influencing factors on the development of pressure ulcers in patients undergoing surgery which lasted more than two hours. Method: One hundred nineteen surgical adult patients were included in the study. Data was measured on each participant from December 2003 to February 2004. It was collected using a structured researcher-administered sheet and analyzed by descriptive statistics, t-test, chi-square test and logistic regression analysis. Result: The prevalence of a perioperative pressure ulcer was 26.1%. The level of moisture, friction and shear, length of surgery, and perioperative irrigation were significantly higher in the pressure ulcer group than those in the non-pressure ulcer group. The level of activity and level of consciousness were significantly lower in the pressure ulcer group than those in the non-pressure ulcer group. Significant influencing factors on the development of pressure ulcer were 'moisture' and 'irrigation' and those variables explained 23.1% of varience in the development of a pressure ulcer during surgery. Conclusion: It is necessary to develop a strategy to prevent pressure ulcer by taking 'moisture' and 'irrigation' into account during the preoperative, perioperative and postoperative period.

• 대한원격탐사학회지
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• 제16권2호
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• pp.117-133
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• 2000

We studied the sea level variations at Kerguelen island in the South Indian Ocean with ARGOS data and meteorological data during about 1 year(May 1993~April 1994) through using filter, spectral analysis, coherency and phase, and found characteristics for the two oceanic signal levels(detided oceanic signal level, h$_{detided}$ and seasonal oceanic level, h$_{corr.ib}$). The forms of atmospheric pressure variations are good agreed to between ARGOS data and meteorological data in the observed periods. This Kerguelen area shows the inflow of an air temperature(gain of a radiant heat) into the sea water and the stagnation of high atmospheric pressure bands in summer, and the outflow of a sea water temperature(loss of sensible and latent heat) toward the atmosphere and the stagnation of low atmospheric pressure bands in winter. The seasonal difference of sea level between summer and winter is about 1.6cm. Both the detided oceanic signal level(h$_{detided}$) variation and the inverted barometer level(h$_{ib}$) variation have a strong correlation for T>1day period bands. The characteristics of h$_{detided}$ variation are not decided by the influence of any meteorological distributions (atmospheric pressure), but the influence of other factors(bottom water temperature) for T>2days periods bands. h$_{corr.ib}$ plays a very important role of sea level variation in the observed periods (especially T>about 180days period bands).

• Journal of Advanced Marine Engineering and Technology
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• 제37권4호
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• pp.384-390
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• 2013

최근 반도체, LCD, 첨단전자산업 관련 분야의 급팽창으로 고압 액화가스 사용이 증가함에 따라 극저온 용기 및 저장탱크도 대형화되는 추세이다. 저장탱크 내의 잔존량을 측정하기 위해 기존에는 아날로그식 액면계와 압력계를 이용하고 있으나 이는 측정이 불편하고 정밀도가 부정확하여 정확한 양을 측정하기가 어렵다. 이에 본 연구에서는 차압센서를 이용하여 극저온 액화가스 저장탱크의 압력과 액면 높이를 측정하고 유선통신기능으로 PC 모니터링이 가능하도록 하며, 모바일 프린터를 연결하여 특정데이터가 출력 가능하도록 디지털식 액면측정장치를 설계한다.

• Journal of Korean Biological Nursing Science
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• 제12권1호
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• pp.8-15
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• 2010

Purpose: The purpose of this study is to investigate the effects of relaxation on stress and blood pressure of the college students induced by a cognitive distress game. Methods: The subjects for this research were 18 individuals whose stress index scores were below 4.0 (Asan city). The 18 subjects were divided into two, 9 students were assigned to the experimental group and the other 9 students to the control group randomly. Survey was used to gather data to recognize general characteristics and the level of stress and blood pressure were measured before and after cognitive distress game and relaxation. The gathered data were analyzed with frequency, $X^2$-test, Wilcoxon signed ranks test and Mann Whitney U test using SPSS 14.0 program. Results: Both level of stress and blood pressure displayed a statistically significant difference pre and post cognitive distress game. Relaxation had a statistically significant effect on level of stress. Relaxation, however, did not have statistically significant effect on blood pressure. Conclusion: The above results suggest that while relaxation was effective in reducing level of stress for college students, and therefore recommendable as a means to deal with stress. However, to investigate the effects on physiological index such as blood pressure, further research is needed.

• 소음진동
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• 제7권6호
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• pp.919-929
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• 1997

Induction motors are used in many areas to transform electrical energy to mechanical energy. In the design of an induction motor, not only energy efficiency but also noise becomes an important factor. To effectively address the noise problem, it will be convenient if one can see where and how noise is generated and propagated. In this study sound radiation by an induction motor is visualized using cylindrical acoustic holography. To minimize the bias error by window effect Minimum Error Window(MEW) is used. Its performance is verified by numerical simulations. Based on these theoretical understanding, sound pressure measurement with an induction motor are performed. Not only sound radiation are visualized but sound pressure level and sound power level are also estimated. Results show that the main source is located at nearly bottom part of the motor and the total sound pressure level is 49dB, which satisfies the guideline value suggested by the KS C 4202.

• Nuclear Engineering and Technology
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• 제44권1호
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• pp.89-102
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• 2012

The buffer and backfill are important components of the engineered barrier system in a high-level waste repository, which should be constructed in a hard rock formation at a depth of several hundred meters below the ground surface. The primary function of the buffer and backfill is to seal the underground excavation as a preferred flow path for radionuclide migration from the deposited high-level waste. This study investigates the hydraulic conductivity and swelling pressure of Kyungju Ca-bentonite, which is the candidate material for the buffer and backfill in the Korean reference high-level waste disposal system. The factors that influence the hydraulic conductivity and swelling pressure of the buffer and backfill are analyzed. The factors considered are the dry density, the temperature, the sand content, the salinity and the organic carbon content. The possibility of deterioration in the sealing performance of the buffer and backfill is also assessed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.742-742
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• 2003

This study is about the effect of the sound pressure level of reverberation on stage acoustics. There are several electro-acoustics systems to enhance the room acoustics of concert hails but not many studies on the stage acoustics for the musicians who plays on the stages. To investigate the effect of reverberation on stage acoustics, the reverberation time of a test room has been controlled through a 4 channel speaker system, and the preferred reverberation level has been selected by performing musicians. As a result, the sound pressure level of reverberation seems to affect the perception of stage acoustics which motivates musicians' performances.

• 화약ㆍ발파
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• 제29권2호
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• pp.81-88
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• 2011

발파공법 위주의 공사를 진행하다 보면 민원발생의 대부분을 차지하고 있는 발파공해는 소음과 진동이다. 이로 인해 발파설계시 안정성을 가장 우선적으로 고려하며, 그중에서도 수중소음을 제어하기 위한 노력이 필요하다. 본 연구에서는 발파로 인한 공사 작업이 진행될 때 거리와 지발당장약량을 적용하여 수중음압을 예측하고 그 수중음압을 이용하여 얻은 수중음압레벨 예측값의 타당성을 검토해 보기 위해 실제 측정한 지역과 다른 지역에서 검증을 하여 실제 측정값과 예측값을 비교해 보았다.