• Tribology and Lubricants
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• 제16권5호
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• pp.324-331
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• 2000

Wear characteristics of Plastic and Nylon pinions against steel gear were studied to gain a better understanding of their tribological behaviors. Wear tests were conducted with power circulating gear test rig under dry contact conditions. Specific wear rates were measured as a function of applied load and the number of revolution. The worn teeth surfaces were examined with a profile projector and a camera. Nylon pinion showed lower specific wear rates than acetal pinion, but suffered teeth breakage under high load per unit tooth width. The dominant wear mechanisms found were adhesion and abrasion.

• 동력기계공학회지
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• 제8권2호
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• pp.39-44
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• 2004

The effects of the STS 304 hollow cylinder property variations on the non-steady heat conduction are considered in this paper. In the non steady state, the specific heat and conductivity are depended on the temperature variations, and these properties affect to the governing equation on heat conduction. But the most of numerical analysis on heat conduction is assumed to constant properties which is conductivity and specific heat. Assuming that the properties are reacted sensitively, the numerical results can have the difference of between constant properties with non constant properties. The main parameters are specific heat and conductivity. The temperature distributions of the STS 304 hollow cylinder became in steady state after 4 minutes in case of the constant properties. As the conductivity is varied with temperature, the temperature distributions became in steady state after 15 minutes. Therefore, a numerical analysis of the non steady state heat transfer is so important in case of varying temperature.

• 한국대기환경학회지
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• 제31권6호
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• pp.530-537
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• 2015

The wet electrostatic precipitator (wet ESP) is an effective control device which removes submicron particles reentrained in a collection plate and water soluble gas. However, its collection efficiency decreases, as its operation is subject to water-induced distortion of the collection electrode. In order to make up for the limitation, we modified the wet ESP system by installing electrosprayed discharge electrodes. The modified wet ESP system can wash both the collection plate and discharge electrode. As a result, we were able to fabricate a compact wet ESP with a small specific collecting area ($0.18m^2(m^3/min)$) that can accomplish a high collection efficiency of fine particles (97.1%). In addition, the device obtained a relatively low specific corona power of approximately $10W/(m^3/min)$.

• 한국식품과학회지
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• 제18권3호
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• pp.187-191
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• 1986

미강(쌀겨)의 유지, 단백질 및 vitamin을 효과적으로 활용하기 위한 연구로서, 미강(수분함량 9.5% 및 15. 6%)을 extrusion cooking 처리장치로서 주어진 specific dower consumption ($42.1{\sim}67.9w/kg$범위)extrusion temperature ($99{\sim}135^{\circ}C$범위) 조건에서 extrusion cooking하여, 미강이 함유하고 있는 thiamine, riboflavin 및 niacin의 잔동율에 관하여 연구한 결과를 요약하면 다음과 같다. 미강에 함유되어 있는 thiamine, riboflavin 및 niacin의 잔존율은 extrusion cooking 처리시의 원료수분함량에 영향을 받으며, 수분함량이 많으면 적은 specific power consumption 및 낮은 extrusion temperature에서도 이들 vitamin의 파괴현상이 더 일어난다. 동등한 수분함량의 원료미강을 extrusion cooking 처리할 때, specific power consumption이 커질수록 그리고 extrusion temperature가 높을수록 이들 vitamin의 잔존율이 저하된다. 그리고 전extrusion cooking 조건에서 thiamine은 $89.9{\sim}97.0%$, riboflavin은 $83.4{\sim}97.3%$, niacin은 94.0%. riboflavin은 $83.4%{\sim}97.3%$ 그리고 niacin은 $94.0{\sim}97.7%$의 잔존율을 보이므로써, 전반적으로 순간고온압출공정인 extrusion cooking이. 가열처리보다 높은 vitamin 잔존율을 나타내고 있었다.

• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.139-142
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• 2001

The one of important parameter involved in the calculation of internal radiation dose to the human body is the biological half-life of the radionuclide. The biological half-life is population specific and may differ from one population group to another. So the effective half-life of tritium exposure based on urinal bioassay measurement of Wolsong Nuclear Power Plants was investigated and studied.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 통신소사이어티 추계학술대회논문집
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• pp.140-144
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• 2003

A sensor network consists of many low-cost, low-power, and multi-functional sensor nodes. One of most important issues in of sensor networks is to increase network lifetime, and there have been researches on the problem. In this paper, we propose a routing mechanism to prolong network lifetime, in which each node adjusts its transmission power to send data to its neighbors. We model the energy efficient routing with power control and present an algorithm to obtain the optimal flow solution for maximum network lifetime. Then, we derive an upper bound on the network lifetime for specific network topologies.

• Korean Journal of Acupuncture
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• 제28권3호
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• pp.85-98
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• 2011

Objectives : The aim of this thesis is to examine the effect of acupuncture treatment at the GB37 on normal humans by using the power spectral analysis of the EEG. Methods : EEG (Electroencephalogram) power spectrum exhibits site-specific and state-related differences in specific frequency bands. In this thesis, the power spectrum was measured by the complexity. the 32 channels EEG study was carried out in the 13 subjects (12 males ; age=22.58 years old, 1 females ; 22 years old). Results : In the ${\alpha}$ (alpha) band, the power values at F7, F3, F4, F8, FTC2, C4, T4, CP1, CP2, TCP2, TT2, Pz, P4, Po1, Po2, O1, Oz, O2 channels (p<0.05) during the GB37-acupoint treatment were significantly changed. And in many channels were decreased. In the ${\beta}$ (beta) band, the power values at Cz, C4, T4, Tcp1, T6, Po1, O1, Oz, O2 channels (p<0.05) during the GB37-acupoint treatment were significantly changed. And in many channels were decreased. In the ${\delta}$(delta) band, the power values at Fp1, TT2 channels (p<0.05) during the GB37-acupoint treatment were significantly changed. And in many channels were decreased. In the $\theta$ (theta) band, the power values at Fp1, F8, FTC2, Pz channels (p<0.05) during the GB37-acupoint treatment were significantly changed. And in many channels were decreased. Conclusions : This results suggest that the acupuncture treatment at the GB37 significantly mostly change the power spectrum value on the alpha (18 channels), beta (9 channels) bands.

• 대한기계학회논문집B
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• 제27권7호
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• pp.929-937
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• 2003

In general, the electric motor for driving the centrifuge of Decanter type is selected based on the power(starting power) necessary to start the bowl and the screw shaft. However the operation cost of the machine is dependent on the power needed at a steadily operating condition, including the power against the bearing friction and that for the sludge removal. In this paper, the formulation for the sludge-removal power is presented. Sample calculation for a specific design shows that the sludge-removal power is increased with the friction coefficient. It also reveals that the power is mainly dependent on the length of the screw blade rather than the beach angle. Further it is shown that the power increases in square of the rotational speed of the machine.

• 전기의세계
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• 제29권12호
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• pp.804-808
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• 1980

The specific objective of this paper is to develop an useful power flow program for real time applications. Great emphasis has been put to the combination of algorithms and programming techniques for high speed, low storage, reliability, versatility and simplicity. A practical application in several cases has produced satisfiable results.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.64.2-64.2
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• 2010

In order to improve the overall power conversion efficiency in dye-sensitized solar cells (DSSCs), it is very important to secure the sufficient surface area of photocatalytic nanoparticles layer for absorbing dye molecules. It is because increasing the amount of dye absorbed generally results in increasing the amount of light harvesting. In this work, we proposed a new method for increasing the specific surface area of photocatalytic titanium oxide ($TiO_2$) nanoparticles by using an inorganic templating method. Salt-$TiO_2$ composite nanoparticles were synthesized in this approach by spray pyrolyzing both the titanium butoxide and sodium chloride solution. After aqueous removal of salt from salt-$TiO_2$ composite nanoparticles, mesoporous $TiO_2$ nanoparticles with pore size of 2~50 nm were formed and then the specific surface area of resulting porous $TiO_2$ nanoparticle was measured by Brunauer-Emmett-Teller (BET) method. Generally, commercially available P-25 with the average primary size of ~25 nm $TiO_2$ nanoparticles was used as an active layer for dye-sensitized solarcells, and the specific surface area of P-25 was found to be ~50 $m^2/g$. On the other hand, the specific surface area of mesoporous $TiO_2$ nanoparticles prepared in this approach was found to be ~286 $m^2/g$, which is 5 times higher than that of P-25. The increased specific surface area of $TiO_2$ nanoparticles will absorb relatively more dye molecules, which can increase the short curcuit current (Jsc) in DSSCs. The influence of nanoporous structures of $TiO_2$ on the performance of DSSCs will be discussed in terms of the amount of dye molecules absorbed, the fill factor, the short circuit current, and the power conversion efficiency.