• Computers and Concrete
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• 제27권1호
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• pp.13-20
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• 2021

In this paper, the elevated temperature on a concrete-galvalume composite beam's flexural strength based on the numerical and experimental methods is investigated. The strategy is to perform modeling and simulation of the flexural test based on finite element method (FEM) at room temperature and validate its results to experimental data at the same temperature. When the numerical model was proven valid, the model was utilized to simulate the effect of elevated temperatures on the composite element. The study concludes that the flexural strength of the beam decreases at higher temperature. Additionally, it was shown that cracking moments is susceptible to temperature fluctuation and the failure modes are sensitive concerning the elevated temperature.

• 감성과학
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• 제9권4호
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• pp.353-366
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• 2006

이 연구의 목적은 백색 LED 조명의 광학적 특성을 분석하고 그 특성에 따라 반응하는 학생과 교사들의 감성 반응을 평가하는 데 있다. 이를 위해 이 연구에서는 백색 LED모듈 5개를 시제품으로 만들어 광학적 특성을 측정하고 감성 평가용 모형을 제작하여 감성 반응을 평가하여 분석하였다. 감성 평가에 이용된 평가 방법은 의미미분법이고 선정된 문항은 16문항이며, 이 문항의 신뢰성과 타당성을 검증하기 위하여 예비 실험을 통하여 신뢰도 분석과 타당도 분석을 하였다. 이 과정에서 4가지 요인을 추출하였는데 제 1요인은 활동성, 제 2요인은 안정감, 제 3요인은 역량성, 제 4요인은 감성이미지 요인이라고 명명하였다. 색온도에 따른 감성 평가의 결과는 활동성과 역량성 요인에서는 색온도가 높은 조명을 선호하였으며 , 안정감 요인에서는 색온도가 낮은 조명을 선호하였다. 감성이미지 요인에서는 색온도와 관련 없이 5800K인 청색 계통의 조명을 선호하였다. 연색지수에 따른 감성 평가의 결과는 활동성, 안정감, 감성이미지 요인에서는 고연색 조명을 선호하였으며, 역량성 요인에서는 중 연색 조명을 선호하였다.

• 폴리머
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• 제33권4호
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• pp.319-325
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• 2009

편광필름용 점착제를 합성하기 위해 아크릴 단량체를 사용하여 용액중합이 수행되었다. 사용된 아크릴 단량체는 2-ethylhexylacrylate, butylacrylate, acrylic acid였으며, 비율은 점착제의 유리전이온도 $-40^{\circ}C$에 맞추어 2-ethylhexylacrylate: butylacrylate: acrylic acid=25:50:3.5로 하였다. 중합된 점착제에 커플링제를 1 wt% 첨가하였을 때 점착제의 광투과율이 매우 증가하였다. 이러한 현상은 커플링제의 Si-O 결합이 액정셀에 대한 점착력을 향상시킨 결과임을 알 수 있었다. 가교제를 단량체 대비 0.5, 1.0, 1.5 wt% 첨가하였을 매 가교제의 함량이 증가할수록 초기점착력은 감소하고 응집력은 증가하였다. 접촉각 분석에서 가교제의 함량이 증가할수록 표면에너지가 커져 접촉각이 감소하였다. 내열성 측정에서 가교제의 증가나 온도변화에 관계없이 아크릴 점착제는 우수한 내열성을 보였으며 절단면의 관찰에서 가교제의 함량이 증가할수록 절단면이 매끄럽고 깨끗하였다. 종합적으로 점착제의 초기점착력, 응집력, 표면에너지, 절단면의 상태 등을 고려하여 적정 가교제의 투입량을 1.0 wt%로 확정하였다.

• The Journal of the Acoustical Society of Korea
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• 제20권1E호
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• pp.3-6
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• 2001

Sound pressure level (SPL) measurements were performed on a controlled test track vehicle coast-by runs of a passenger vehicle with six different sets of tires across a range of temperatures. A small but significant reduction of noise level with positive temperature increases was observed for some tires. The temperature gradient of the different tires at 80㎞/h ranged from -0.07 to + 0.01 dB/℃. Frequency analysis of the tire noise identified that noise content in the range of 1,300 to 1,900Hz was particularly sensitive to temperature changes. Differences in SPL due to speed and tire type were much greater than that due to temperature.

• Journal of Biosystems Engineering
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• 제16권4호
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• pp.363-371
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• 1991

It is important to measure the somatic informations for stockbreeding automatization. This study was carried out for the development of wireless measurement system of temperature in living animals. New method to measure somatic temperature was developed using the single-channel wireless instrument. This system was constructed by oscillator, temperature sensor, wireless transmitter and receiver circuit, single processing circuit, and microcomputer. Two types of sensor were used and compared to measure the temperature. The thermistor sensor was more sensitive and accurate than platinum resistance sensor, however both sensors were performed efficiently. The single-channel wireless measurement systems developed could measure the somatic temperature successfully and offered a versatile system.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.391-396
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• 2001

In order to estimate thermal cracking in mass concrete and to decide the removal time of the forms outside the concrete structures in wintertime, temperature measurement is indispensible. Until now, the measurement system employs thermocouple type. In this paper, we introduce economical and accurate NTC(Negative Temperature Coefficient) ceramic type measurement system. In principle, NTC ceramic type sensor is very sensitive in the range -20~15$0^{\circ}C$. In this range, the signal change is so large that the sensor needs less amplification than thermocouple. Therefore, not only the sensor itself is inexpensive but also the system is too. In this experiments the temperature of the NTC system are identical to those of thermocouple. In conclusion, inexpensive NTC thermistor system is very adequate to the temperature measurement during concrete curing.

• 한국인쇄학회지
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• 제14권1호
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• pp.17-29
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• 1996

N-substituted acrylamide hydrogel is reported to have the feature of bing transparent and sensitive enough to response to a temperature stimulus below the temperature of phase transition. Especially at the near of 35 C it becomes shrunk and opaque very quickly. It has also the characteristic of reversing swelling and shrinking. The experiment showed that it is possible to produce a functional gel of super water absorption with the process of free radical polymerizing PVA(polyvinylalcohol) and PAA(polyacrylamide), and crosslinking. The ratio of shrinking and swelling caused by copolymerization rises 10% to 80% at the each temperature of 20 C, 30 C, 40 C, respectively. Phase transition temperature of this gel by copolymerization is50 C while that of ordinary N-substituted acrylamides is between 32~35 C. This temperature reaches the rearing limit of animals and plants so that volumetric transition polymer gel can be ulilized in varying fields such as agriculture/gardening which are water-using field, on-off switch sensing temperature and volumetric variation, processing of liquid wastes and civil engineering works, architecture and electronics. We have no doubt that this material will be the high-functional resin in the hi-tech age of the near future.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.620-626
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• 1988

GaAs solar cells may be the most attractive and efficient power source of a satellite. GaAs is more radiation tolerant and less temperature sensitive than widely used silicon. $Al_{x}$ Ga$_{1-x}$ As/GaAs solar cells have been designed and fabricated by Liquid Phase Epitaxial method. GaAs solar cells, of which structure is about 0.2 .mu.m p$^{+}$ - window layer, 0.6-1.O .mu.m Ge-doped p-layer. 3.mu.m n-GaAs layer and n$^{+}$ - buffer layer, have been characterized as a function of operating temperature from 25 .deg.C to 130 .deg.C. Open circuit voltage decreases linearly with increasing temperature by 1.4-1.51 mV/ .deg.C while degradation of silicon solar cells is about 2.2-2.5 mV/ .deg.C, short circuit current does not increase much with increasing temperature. Relative efficiency decreases with increasing of temperature by about 0.21-0.29 %/ .deg.C. Efficiency degradation of silicon solar cells with temperature is known to be about 0.5%/ .deg.C and our results show GaAs solar cells may be an excellent candidate for concentrated solar cells.ells.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.576-580
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• 2000

Tire-pavement noise is a significant portion of noise coming from road vehicles and is therefore a logical focus of efforts to reduce overall traffic noise. A small but significant reduction of noise level with positive temperature increases was observed for some tires. The reduction was evident in two of the tires at 53 km/h and five of the tires at 80 km/h. The temperature gradient of the different tires at 80 km/h range from -0.07 to +0.01 dB/$^{\circ}C$. Frequency analysis of the tire noise identified that noise content in the range of 1,300 to 1,900 Hz is particularly sensitive to temperature changes.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.300-303
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• 2008

In the present study, the simple form of the heat transfer equation were suggested to estimate the temperature variation inside the oil pipe in order to determine the thickness of the insulating materials to retain the working oils below the critical temperature. The conservation of the thermal energy at arbitrary time were modeled to one dimensional unsteady equation with the empirical formula or data. The calculating results for non-insulation case showed that the temperature were very sensitive to the thermal convection by the velocity of the external wind. For insulation case, the insulation material which has higher density and specific heat, lower thermal conductivity should be chosen with more brighter coloring outside the pipe in order to retain the working oils below the critical temperature.