• Journal of Fisheries and Marine Sciences Education
• /
• v.18 no.3
• /
• pp.229-235
• /
• 2006

This study investigated physiology and psychological response of subjects, when heat pump was operated long time within comfort temperature range. Eight subjects were participated for the experiment. Their age was from 22 to 25 years old. The results of this experiment will propose basic data for improving comfort control algorithm in fluctuating environment by using heat pump. When indoor temperature was controlled by heat pump, the conclusion was as follows. 1) When votes of subjects was considered, the thermal comfort neutrality or lower range helped formation of comfort sensation for subjects. 2) When room temperature was lower, thermal comforts of shoulder, knee and foot with subjects thermal comfort showed high correlation. And when room temperature was higher, thermal comfort of face region with subjects thermal comfort showed high correlation. 3) The necessity of temperature change after 50 minutes from initially operating heat pump demands the additional analysis against the physiological signal.

• Journal of the Korean Society of Safety
• /
• v.29 no.6
• /
• pp.166-171
• /
• 2014

Nuclear power plants are equipped with the reactor trip system (RTS) and the engineered safety features actuation system (ESFAS) to improve safety on the normal operation. In the event of the design basis accident (DBA), a various of post accident monitor(PAM)systems support to provide important details (e.g. Containment pressure, temperature and pressure of reactor cooling system and core exit temperature) to determine action of main control room (MCR). Operator should be immediately activated for the accident mitigation with the information. Especially, core exit temperature is a critical parameter because the operating mode converts from normal mode to emergency mode when the temperature of core exit reaches $649^{\circ}C$. In this study, uncertainty which was caused by exterior environment, characteristic of thermocouple/connector and accuracy of calibrator/indicator was evaluated in accordance with ANSI-ISA 67.04. The square root of the sum of square (SRSS) methodology for combining uncertainty terms that are random and independent was used in the synthesis. Every uncertainty that may exist in the hardware which is used to measure the core exit temperature was conservatively applied and the associative relation between the elements of uncertainty was considered simultaneously. As a result of uncertainty evaluation, the channel statistical allowance (CSA) of single channel of core exit temperature was +1.042%Span. The range of uncertainty, -0.35%Span ($-4.05^{\circ}C$) ~ +2.08%Span($24.25^{\circ}C$), was obtained as the operating criteria of core exit temperature.

• The Journal of Korean Academy of Prosthodontics
• /
• v.44 no.4
• /
• pp.374-382
• /
• 2006

Purpose: This study was designed to investigate the present conditions of illumination techniques in dental clinics in order to contribute improvement of operating environment. This study also aimed exploring qualitative and quantitative luminous intensity required for color temperature in dental clinic illumination, which was a critical part of esthetic dentistry. Materials and methods: A total of forty-eight local dental clinics were selected for sampling a) luminous intensity, and b) color temperature. The author measured the luminous intensity and the color temperature with lux meter and color meter respectively between 12pm and 2pm. The dental unit chair placed in the general operation positions were kept the distance 60 cm then all dental units were measured three times and averaged. The author measured the luminous intensity and color temperature with both common dental operating light and then without operating light in different office environments. The study was conducted under three conditions: 1 artificial illumination in clear day light 2. artificial illumination in cloudy day light, and 3. artificial illumination alone. Results : The results obtained were as follows. 1. The average luminous intensity in dental clinic lighting was 425 lux which was not sufficient to produce the optimal shade of the patient's teeth. Furthermore, the average luminous intensity even in full operating lighting was 9532 lux which fell short of the required level of 10,000 lux. 2. The average color temperature of all dental clinics surveyed was 5169 K which met the optimal range. However, only 33.3% fell in the correct region between 5,000-5,500 K as 25% were over 5,500 K and 41.6% were below 5,000 K. As a result, 66.7% were under insufficient color temperature conditions. 3. The dental unit chair placed next to a window, hence exposure to natural lighting, had significantly higher luminous intensity and color temperature compared to the dental unit chair which didn't have a window or natural lighting. 4. The data analysis revealed that only 6.3% of the dental clinic were met the standard of the average luminous intensity and color temperature.

• ETRI Journal
• /
• v.31 no.5
• /
• pp.601-603
• /
• 2009

This letter presents a high performance 2.4 GHz two-stage power amplifier (PA) operating in the temperature range from $-30^{\circ}C$ to $+85^{\circ}C$ for IEEE 802.11g, wireless local area network application. It is implemented in InGaP/GaAs hetero-junction bipolar transistor technology and has a bias circuit employing a temperature compensation technique for error vector magnitude (EVM) performance. The technique uses a resistor made with a base layer of HBT. The design improves EVM performance in cold temperatures by increasing current. The implemented PA has a dynamic EVM of less than 4%, a gain of over 26 dB, and a current less than 130 mA below the output power of 19 dBm across the temperature range from $-30^{\circ}C$ to $+85^{\circ}C$.

• Journal of the Optical Society of Korea
• /
• v.3 no.2
• /
• pp.74-79
• /
• 1999

We present a simple design rule for a passive temperature-compensating optical package. We also present experimentally that a package fabricated by using the design rule compensates the temperature dependence of the resonant wavelength of an optical long period fiber grating by varying the strain inside the fiber, The package fabricated in this work consists of two pieced of brass tube, 10 mm long, and a piece of nylon rod, 45.4 mm long. It is shown that the package can compensate the temperature-induce wavelength shifts of the long period grating to a range of 6.8 pm/$^{\circ}C$, compared with 0..48 nm/$^{\circ}C$ for an uncompensated grating. The reduced strength of the fiber caused by exposure to ultraviolet limits the performance of the package to the range operating temperature form -3 $^{\circ}C$ to 7$0^{\circ}C$.

• Journal of the Korean Institute of Telematics and Electronics C
• /
• v.34C no.12
• /
• pp.37-42
• /
• 1997

A new temperature and supply-insensitive CMOS current reference circuit was designed and tested. Te temperature insensuitivity was achieved by eliminating the mobility dependence term through the multiplication of two current components, one which is proportional to mobility and the other which is inversely proportional to mobility, by using a newly designed CMOS square root circuit. The CMOS sqare root circuit was derived from its bipolar counterpart by operating the MOS transistors in the subthreshold region. The supply insensitivity was achieved by using an internal voltage generator. Te test chip was designed ans sent out for fabrication by using a 2.mu.m double-poly double-metal n-well CMOS technology. When an external voltage source was used for the square root circuit, the maximum variation and the average temperature sensitivity were measured to be 3% and 21.4ppm/.deg.C, respectively, for the temperature range of -15~130.deg.C. The maximum current variation with supply voltage was measured to be 3% within the commerical supply voltage range of 4.5~5.5V at 30.deg. C.

• Transactions of the Korean hydrogen and new energy society
• /
• v.29 no.4
• /
• pp.393-400
• /
• 2018

To confirm the operating range of two oxygen carriers for chemical looping combustion system, the effects of operating variables on solid circulation rate were measured and discussed using a two-interconnected circulating fluidized bed system at ambient temperature and pressure. Moreover, suitable operating ranges to avoid choking of the fast fluidized bed (air reactor) were confirmed for two oxygen carriers. A continuous long-term operation of steady-state solid circulation more than 24 hours was also demonstrated within the operating windows. Finally we could confirm that those two oxygen carriers are suitable for chemical looping combustion system with high solid circulation rate and smooth solid circulation.

• Proceedings of the SAREK Conference
• /
• 2005.11a
• /
• pp.317-322
• /
• 2005

This study is aimed to analyze the effects of heat pipe shape on the heat transfer in solar collector with a axial grooved heat pipe. In the design of a heat pipe. two of the most important criteria to be met are the operating temperature range and the maximum heat transport capacity, When the operating temperature range is known and the working fluid has been selected, the maximum heat transport capacity depends strongly on capillary pressure and liquid flow. The heat transport capacity of the heat pipe will depend on the geometry of the heat pipe, the wick structure. the vapor channel shape. groove number. cooling temperature. condenser length and pipe diameter. So various shapes are used for mathematical models of two-phase flow in grooved heat pipe. From the results. the adequate groove shape and scale are presented by considering the heat transport and capillary limitation.

• Transactions of the Korean hydrogen and new energy society
• /
• v.29 no.5
• /
• pp.442-449
• /
• 2018

Research on High temperature polymer electrolyte fuel cell (HT-PEMFC) has actively been conducted all over the world. Since the HT-PEMFC can be operated at a high temperature of $120-180^{\circ}C$ using phosphoric acid-doped polybenzimidazole (PBI) electrolyte membrane, it has considerable advantages over conventional PEMFC in terms of operating conditions and system efficiency. However, If the thermal distribution is not uniform in the stack unit, degradation due to local reaction and deterioration of lifetime are difficult to prevent. The thin plate separator reduces the volume of the fuel cell stack and improves heat transfer, consequently, enhancing the cooling effect. In this paper, a large area flow field of thin plate separator for HT-PEMFC is designed and sub-stack is fabricated. We have studied stack performance evaluation under various operating conditions and it has been verified that the proposed design can achieve acceptable stack performance at a wide operating range.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.22 no.8
• /
• pp.659-664
• /
• 2009

This paper describes lightning impulse operating duty performance and temperature dependence of series gap type for transmission line arresters. The ageing parameters of lightning arresters are impulse current, moisture ingress, temperature ageing and so on. Especially it is important to estimate the change of electrical characteristics by lightning impulse current. In the discharge withstand test, total energy applied to the ZnO arrester each time is 4/10 ${\mu}s$, 30 kA. and in the operating duty test, the arrester has passed the test if thermal stability is achieved, if the residual voltage measured before and after the test is not changed by more than 5 %, and after the test reveals no evidence of puncture, flashover or cracking of the ZnO block. As a results, the residual voltage was in the range of 17.2${\sim}$20.3 kV and ZnO block bear up against at 2 shot of series impulse current of 30 kA. Also it was so excellent that the mechanical destruction does not occur at the 2 groups of 5 impulses current of 2/20 ${\mu}s$ 10 kA. According to the tests, it is thought that the ZnO arrester shows good stability with impulse current test. and it was found that the ambient temperature is increased resistive leakage current was increased in the range 47.3${\sim}$167.4 ${\mu}A$.