• 태양에너지
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• 제19권1호
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• pp.67-75
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• 1999

The effect of radiation heat transfer was investigated under various operating conditions in a circular tube with circumferential fins and circular disks. Using a finite volume technique(FVM) for steady laminar flow, the governing equations were derived in order to simulate the flow and temperature fields. In addition, the P-1 approximation and the Weighted Sum of Gray Gas Model(WSGGM) were used for the radiation transport equation(RTE). From the results, radiation heat transfer was significant compared to convection heat transfer. These results will be applied to the design of the heat exchanger for a condensing bolier, which were developed for domestic heating.

• Current Optics and Photonics
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• 제3권3호
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• pp.243-247
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• 2019

We have developed a compact, wavelength-selectable, Q-switched Nd:YAG laser at mid ultraviolet for chemical warfare agent detection. The fundamental wave at 1064 nm is delivered by a pulsed solid state laser incorporating with a square-type Nd:YAG rod in a resonator closed by two crossed Porro prisms for environmental reliability. The output energy at 213 nm ($5{\omega}$) and 266 nm ($4{\omega}$) by ${\chi}^{(2)}$ process in the sequentially disposed BBO crystals are measured to be 6.8 mJ and 15.1 mJ, respectively. The output wavelength is selected for $5{\omega}$ and $4{\omega}$ by a motorized wavelength switch. The energy ratio of the $5{\omega}$ to the $4{\omega}$ is varied from 0.05 to 0.85 by controlling the phase matching temperature of the nonlinear crystal for sum-frequency generation without change of the output pulse parameters.

• 한국광학회지
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• 제21권3호
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• pp.123-128
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• 2010

이터븀 광격자 시계의 검색 레이저로 쓰기 위하여, WG-PPLN를 사용하여 1319 nm 파장의 Nd:YAG 레이저와 1030 nm 파장의 Yb 도핑된 광섬유 레이저의 합주파수 (578.4 nm)를 발생시켰다. 이터븀 광격자에서 시계 전이선을 분광하기 위해서는 1 Hz 수준의 선폭을 가지는 검색 레이저가 필요하기 때문에, 합주파수로 발생된 노란색 레이저의 주파수를 초공진기에 안정화하여 선폭을 축소하였다. 초공진기는 선팽창 계수가 낮은 ULE로 제작되었고, 진동으로 인한 영향이 작은 받침점에서 능동형 제진대 위에 설치되었다. 공기 굴절률의 영향을 제거하기 위하여 이 초공진기를 진공 체임버 내부에 설치하고, 온도를 1 mK 수준에서 안정화 하였다. 또한, 이 장치들을 방음 체임버 안에 설치하여, 소리로 인한 잡음을 막아 주었다. 실험에 사용된 초공진기의 광자 수명시간으로부터, 그 예리도가 380 000으로 측정되었다.

• 산업경영시스템학회지
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• 제40권1호
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• pp.124-130
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• 2017

This study is aimed to find out whether there is difference in the physiological change of a human body according to the illumination and color of interior space or not and to specify the effect of the condition of illumination and color, respectively on the attention. In order to do so, White and Green were selected for colors and 4,000k, 5,000k, and 6000k were done for color temperature, and then attention was identified. Examining the results, the more color temperature increased, the more attention improved (P < 0.05), and in the case of EEG, ${\alpha}$ wave decreased while performing the task of attention (P < 0.01), and ${\beta}$ wave decreased more in Green than White in color condition, and it increased more in 4,000k than 5,000k and 6,000k (p < 0.05) in color temperature condition. To sum up, color condition didn't contribute to the attention much, in the case of color temperature, when it is 6,000k, it is judged that it helped to improve attention. It is considered that relaxation contributed to improving attention, as ${\beta}$ wave and sympathetic nerve decreased in 6,000k (p < 0.05). It is judged that the relaxation of tensions which happened due to a beta wave and the reduction of sympathetic nervous system activity in 6,000k, a condition of high color temperature, contributed to the improvement of concentration. In further researches, it is intended that a test will be conducted for the subjects of different ages, and the correlation between color temperature and color stimulation and the influence of them on human body would be observed in subdivided, various test conditions through various color temperature and color stimulation.

• 한국농림기상학회지
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• 제3권4호
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• pp.185-198
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• 2001

본 연구는 잣나무 성숙임분을 대상으로 임령별 국지 기후 조건을 지형기후학적 방법과 공간통계 기법에 의하여 추정하여 잣나무 임분의 연도별 생식생장에 미치는 국지기후의 영향을 구명하고자 하였다. 이를 위해 지형-기후 관계식을 이용하여 연구 대상지의 평균기온, 최고기온, 최저기온, 상대습도, 강수량, 일조시수, 맑은 날수, 흐린 날수에 대하여 월별ㆍ기후치별 평년 값을 도출하고, 공간통계기법에 의하여 연도별ㆍ월별 기후치를 산출하였다. 또한 연구 대상지의 잣나무 임분에 대한 연도별 구과 및 종자 결실량, 낙과량, 형질 등 생식생장의 특성을 파악하였다. 이상의 자료에 근거하여 잣나무 성숙임분의 생식생장에 미치는 국지기후의 영향을 상관분석 및 회귀분석을 통하여 구명한 격과는 다음과 같다. 1년생 구과의 착과수는, 화아분화 연도의 6월과 7월의 평균 일 최저기온, 화아분화 연도의 6월과 7월의 총 강수량, 화아분화 연도 11월 부터 개화수분당년도 4월까지의 흐린 날수 합계와 높은 부의 상관이 인정되어, 화아분화 연도의 강수량이 적고 일조시간이 많으면 착과수도 많아지는 것으로 파악되었다. 2년생 구과의 결실량과 유의적인 상관관계를 나타낸 기후지수가 없었다. 다만 가장 상관계수가 높은 지수로는 결실전년(개화수분당년) 12월부터 결실년도 2월까지 3개월간의 겨울철 강수량이 정의 상관관계를 나타냈다. 낙과량에 영향을 미친 기후요소는 개화수분당년 6월부터 익년 8월까지 15개월 간의 흐린 날수 합계와 개화수분당년 11월부터 익년 3월까지 동계 5개월 간의 강수량이 상관이 높은 것으로 나타났고, 낙과율에 있어서는 개화수분당년 6월부터 익년 8월까지 15개월간의 흐린날수 합계가 가장 영향을 많이 미치는 기후지수로 판명되었다. 구과의 쭉정이량은 구과 성숙 이전의 동계 3개월 간의 강수량과 가장 높은 상관을 보이고 있었으며, 쭉정이율의 경우에는 상대적으로 많은 5개의 기후 지수와 10% 이내의 높은 상관관계를 인정할 수 있었는데, 특히 구과 성숙 이전의 동계 3∼5개월 간의 강수량과 높은 정의 상관관계를 보여 동계기간동안 강수량이 많으면 광합성량이 감소하여 임목의 영양상태가 불건전하게 됨으로써 수정에 방해가 되고 종국적으로는 불량한 종자의 비율이 높아지는 결과를 초래하는 것으로 보인다. 구과무게는 개화수분당년 6월 부터 익년(결실년도) 8월까지 15개월 간의 강수량과 부의 상관을 보여, 수분이후 결실과정까지 강수량이 많으면 광합성에 장애를 주어 구과 1개의 무게가 상대적으로 적어지는 것으로 나타났다. 한편 종자 1개의 평균무게는 결실전 동계기간동안의 강수량 높은부의 상관을 보여 겨울철 강수량이 많으면 광합성율이 저하되고 이는 다시 종자 때의 무게가 적어지는 결과를 보이는 것으로 판단된다. 구과피무게는 결실 전년 11월부터 익년 3월까지 5개월 간의 맑은 날수와 겨울철인 12월부터 2월까지 3개월 간의 맑은 날수와 부의 상관을 보인 반면에, 결실 전년도 5월의 평균기온과는 정의 상관관계를 보였다. 구과피율의 경우에도 구과피 무게와 동일한 경향을 보여, 결실전 동계기간동안의 맑은 날수는 종자생산에 긍정적인 영향을 주는 반면, 결실 전년도 5월의 평균기온이 높으면 부정적인 영향을 주는 것으로 파악되었다.

• 대한치과보철학회지
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• 제45권1호
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• pp.60-70
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• 2007

Statement of problem: The cement-type abutment would be needed for the reduction of its body in order to correct the axis and to assure occlusal clearance. In the case of intraoral preparation, there is a potential risk that generated heat could be transmitted into the bone-implant interface, where it can cause deterioration of tissues around the implant and failed osseointegration. Purpose: The purpose of this study was to assess the difference of the heat transmitting effect on external and internal connection implant types under various conditions. Material and method: For evaluating the effects of alternating temperature, the thermocoupling wires were attached on 3 areas of the implant fixture surface corresponding to the cervical, middle, and apex. The abutments were removed 1mm in depth horizontally with diamond burs and were polished for 30 seconds at low speed with silicone points using pressure as applied in routine clinical practice. Obtained data were analyzed using Mann-Whitney rank-sum test and Wilcoxon / Kruskal-Wallis Tests. Result: Increased temperature on bone-implant interface was evident without air-water spray coolant both at high speed reduction and low speed polishing (p<.05). But, the difference between connection types was not shown. Conclusion: The reduction procedure of abutment without using proper coolant leads to serious damage of oral tissues around the implant irrespective of external and internal connection type.

• Current Research on Agriculture and Life Sciences
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• 제5권
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• pp.134-142
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• 1987

The purpose of this study is to establish more rational and practical planning theory for amusementpark. It analyze and considerate the fluctuation of the people who come and use a Tong-Ch'on amusementpark. The results drawn from this research work are as follows ; There are considerable correlation between use fluctuation and some factors. The factors are season (spring, summer, autumn) as a time, temperature, cloud amount, duration of sunshine, weather (rainy day) as a climate and date (weekday, holiday) as a social system. The important variables are temperature, cloud amount, duration of sunshine and date (week day, holiday) to estimate the user of amusementpark. I can reduce the following two types of regression models. 1.${\log}_eY1=6.9114+0.1135TEM+0.00002_eSUM-0.4068WI+0.4316W3$ ($R^2=0.94$) 2. ${\log}_eY2=7.2069+0.1177TEM-0.0990CLO+0.488W3$ ($R^2=0.95$) Y ; Number of User TEM ; Temperature CLO ; Amount of cloud SUN ; Duration of Sunshine WI ; Weekday W3 ; Holiday Those model is inorder to estimate the user for management of Tong-Ch'on amusementpark and use on the computation of facility size for reconstruction. Besides the amusementpark, city park and outdoor recreation area could estimate of user throuth this method. But, I am not sure about the regression models because I didn't apply the regression models to the other amusementpark, city park or outdoor recreation area. Therefore, I think that this problem needs to study in the future.

• 한국농공학회논문집
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• 제51권6호
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• pp.45-52
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• 2009

This study was conducted in the process that the basic plan of the formation of the thermal energy complex in the Iwon reclaimed land of Taean was being made. Targeting for the large-sized greenhouse to be made in this area, it examined the cooling and heating load and the amount of ventilation, and also analyzed the economic efficiency of heating. The research results are as per the below: The minimum ambient temperature of this area was measured on January 7, 2001, which was $-18.7^{\circ}C$, and the maximum ambient temperature of this area was measured on July 24, 1994, which was $36.7^{\circ}C$. The maximum heating load was 39,011 MJ/h, but the date when the maximum heating load was not consistent with the date when the minimum temperature was measured. The maximum cooling load was 88,562MJ/h, It was approximately 2.3 times of the maximum heating load, which was measured at 14:00 hours on September 4, 2000. The maximum amount of ventilation heat was 138,639MJ/h. Assuming the rate of solar heat use as 10%, 20%, 50%, and 100%, the total sum of cost-benefit would be ￦-193,450,000, ￦-634,930,000, ￦-3,372,960,000, and ￦-9,850,420,000, respectively 20 years later. The break-even point of the geothermal heat pump would be about 4 years for 10% use, about 3 years for 20% or 50% use, and approximately 6 years for 100% use. It was found that 50% use would be most advantageous. In case two systems are combined, the break-even point will be 10 years, 8 years, and 11 years respectively.

• Progress in Superconductivity
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• 제8권2호
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• pp.127-131
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• 2007

We have measured the Hall conductivity (${\sigma}_{xy}$) of c-axis-oriented $MgB_2$ thin films as functions of temperatures and magnetic fields. We found that the Hall conductivity (${\sigma}_{xy}$) is expressed by the sum of two terms, ${\sigma}_{xy}=C_l/H+C_3H$, where the coefficient $C_1\;and\;C_3$ are independent of the magnetic fields and have positive values. The coefficient $C_1$ is strongly dependent on the temperature, while the $C_3$ is weakly dependent on the temperature. We have obtained that the $C_1$ is proportional to $(1- T/T_c)^n$ with n = 4.2, which is consistent with the data observed in $La_{2-x}Sr_xCuO_4$ superconductors with low anisotropy ratio.

• 대한기계학회논문집B
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• 제25권11호
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• pp.1594-1605
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• 2001

In this study, a numerical simulation was developed which was capable of predicting the characteristics of NO formation in pilot scale combustor adopting the air-staged burner flame. The numerical calculation was constructed by means of establishing the mathematical models fur turbulence, turbulent combustion, radiation and turbulent nitric oxide chemistry. Turbulence was solved with standard k-$\xi$ model and the turbulent combustion model was incorporated using a two step reaction scheme together with an eddy dissipation model. The radiative transfer equation was calculated by means of the discrete ordinates method with the weighted sum of gray gases model for CO$_2$and H$_2$O. In the NO chemistry model, the chemical reaction rates for thermal and prompt NO were statistically averaged using the $\beta$ probability density function. The results were validated by comparison with measurements. For the experiment, a 0.2 MW pilot multi-air staged burner has been designed and fabricated. Only when the radiation was taken into account, the predicted gas temperature was in good agreement with the experimental one, which meant that the inclusion of radiation was indispensable for modeling multi-air staged gas flame. This was also true of the prediction of the NO formation, since it heavily depended on temperature. Subsequently, it was found that the multi-air staged combustion technique might be used as a practical tool in reducing the NO formation by controlling the peak flame temperature.