• 한국자원식물학회지
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• 제11권1호
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• pp.70-79
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• 1998

This study was conducted to understand the effects of weather and tapping date on yield and quality of lactree(Rhus verniciflua) sap yield showed a significant positive correlation with the minimum temperature of one day before sap collection at 1% level and with theminimum humidity of theday of sap collection at 5% level. However, the differences between the maximum and the minimum temperatures and humidities of the day of sap collection were negatively correlated with the sap yield at 5% level. Multiple regression analysis indicated that the minimum temperature of one day bofore sap collection and the minumum humidity of the day sap collection were important factors for increasing sap yield. The high sap yield of lactree by Japanese tapping method was recorded during mid-July and early August. Seasonal variation in lactree sap constituents was observed. The sap collected on 15th of August contained the highest urushiol content (68.3%) and the lowest water content resulting in high quality of lactree sap. By reversed-phase HPLC analysis, fove urushiol components were separated from each other depending on the number of doulbe bonds in the side-chain , and seaxonal variation of urushiol composition was noticed. The 3-C15 triene content fo the sap collected on 5th of July was the highest(77.56%) indicating the major component of urushiol which affects lactree sap quality.

• 한국자기학회지
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• 제25권1호
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• pp.4-9
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• 2015

본 연구는 PFC(Planar Flow Casting)프로세스에 의한 Fe기 $Fe_{78}Si_9B_{13}$ 비정질 합금리본 제조에 있어서 습도변화(55~85 %)가 비정질 합금리본의 표면결함 및 자기적 특성에 미치는 영향을 조사하였다. 그 결과, 비정질 합금리본의 접촉면과 자유면에서 관찰된 air pocket/droplet의 크기는 습도가 증가할수록 커지는 경향을 보임과 동시에 표면조도과 함께 크게 증가하였으며, 특히 습도 65 %에서 제조한 표면조도 값이 접촉면($Ra=0.60{\mu}m$, $Rz=3.11{\mu}m$)과 자유면($Ra=0.47{\mu}m$, $Rz=3.00{\mu}m$)에서 모두 가장 낮은 값이 얻어졌다. 또한 $23(OD)^*20(ID)^*20(H)$ 크기의 토로이달 코어로 제조된 자성코어의 연자기적 특성의 경우에도 65 %에서 제조한 비정질 합금리본의 시료에서 $B_s(B_{700})=1.055T$, $H_c=0.083Oe$, 투자율 = 1,197 및 core loss = 0.276 W/kg로 가장 우수한 값이 얻어졌다.

• 콘크리트학회논문집
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• 제17권5호
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• pp.751-760
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• 2005

본 논문에서는 확산과 수분이동에 의한 침투를 함께 고려할 수 있는 염소이온침투 모델을 제시하고 이를 바탕으로 유한요소 프로그램을 개발한다. 개발된 프로그램을 이용하여 습도와 온도가 연속적으로 변화하는 현장상태에 대한 염소이온 침투 해석을 수행한다. 해석과정으로 먼저 수분확산해석을 수행한다. 이 해석에 의한 각 유한요소의 상대습도를 바탕으로 염소이온 침투해석을 위한 재료상수를 구한다. 이러한 재료상수를 이용하여 염소이온 침투해석을 수행하게 된다. 각 유한요소들은 시간과 재령에 따라 연속적으로 변화하는 재료상수 값을 가지게 된다. 내외부의 상대습도 차이가 크면 수분이동에 의한 염소이온 침투의 영향이 커지지만 내외부의 상대습도의 차이는 수분확산에 의해서 재령에 따라 감소하므로 수분이동에 의한 염소이온 침투의 영향은 재령에 따라 감소한다. 반복 습윤은 수분이동에 의한 염소이온 침투의 영향을 증가시켜 철근 주위의 염소이온 농도를 커지게 한다. 현장상황과 같이 건습의 반복이 장기적으로 발생하게 되면 수착과 확산을 함께 고려한 염소이온 침투량이 수분이동을 고려하지 않은 염소이온 침투량보다 매우 크다. 따라서, 항만 콘크리트 구조물에 대한 염소이온 침투해석을 장기재령동안 수행할 경우에는 수분이동 메커니즘을 포함한 수치 모델링을 바탕으로 건습의 반복을 고려하여 해석을 수행하는 것이 해석의 오차를 줄일 수 있을 것이다.

• 한국환경복원기술학회지
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• 제23권5호
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• pp.29-43
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• 2020

Thermal environment of city is getting worse due to severe urban heat island caused by climate change and urbanization. The cooling effect of street tree is regarded as a effective way to ameliorate the urban heat environment. The effect is largely made up of shadow formation and transpiration. This study aims to identify how the transpiration affects the discomfort index by analyzing comprehensive impact of the transpiration on the air temperature and relative humidity. The changes in the amount of transpiration, air temperature, and relative humidity were estimated for Seogyo-dong area which has a lot of floating population in Seoul, at 2 p.m. in dry day in July and August. On average, the transpiration of the street tree decreased the temperature 0.3℃ and increased the relative humidity 2.6% in an hour. As a result of these changes in temperature and humidity, the discomfort index rose mostly(0.036 on average). It was always get rise especially on the day when the discomfort index was above 80(0.05 on average). However, compared with the significant change in temperature and humidity, the variation of the discomfort index itself was very slight(up to 0.107). Therefore, the effect of transpiration by the street trees might not be effective in the planning to improve the thermal environment(especially on the day when the discomfort index is high). It is necessary to select the species of trees and planting location considering the cooling effect of shade formation synthetically.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.57.1-57.1
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• 2011

The effects of relative humidity on the properties of the porous $ZrO_2$ ceramics were investigated in terms of the curing behavior of phenolic resin as a binder. The $ZrO_2$ powders containing 5wt% of phenolic resin were conditioned in a consistent chamber condition at a temperature of $50^{\circ}C$ and different humidity levels (25, 50, 75, and 95%) for 1 h. The exposure of humid atmosphere caused changes of density and microstructure in the green bodies. The higher level the powders were exposed to the humid atmosphere, the lower green density was obtained and the more irregular microstructure was observed due to aggregation by the curing of phenolic resin. After firing, the porosity of specimens has risen from 35.7% to 38.1% and Young's modulus has declined in response to the variation of green density. These results could be explained by the degree of resin cure which was associated with the area under the exothermic peak enclosed by a baseline of DSC thermogram curve. Also, the curing behavior of phenolic resin according to relative humidity has been confirmed by decrease of ether groups which have interacted with the phenolic-OH group and the hexamine as a curing agent. Consequently, it could be demonstrated that increase the relative humidity during fabrication of porous $ZrO_2$ diminished the compaction and properties of specimens after firing owing to curing of phenolic resin.

• 대한인간공학회지
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• 제17권3호
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• pp.41-59
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• 1998

Thermal comfort aspect of a locally-cooled target space in warm and humid environments(typically in the rainy summer season) was studied in view of PPD index. First. theoretical analyses were conducted to examine the effect of the governing parameters(such as air temperature, relative humidity and air velocity, etc.) using a computer model. Secondly, experimental investigations were also performed in a climatic room designed to simulate corresponding thermal conditions of outdoor environments. During the tests, temporal variation of PPD was recorded as functions of climatic variables(outdoor and indoor temperatures, relative humidity and air velocity) for the given human factors(metabolic heat generation and clothing). From both theoretical and experimental investigations, air temperature and air velocity were found to be the most dominant parameters affecting PPD of the target space. Results were summarized as: 1. Relative humidity of the locally-cooled target space tends to approach that of outdoor's as the space is subjected to an ON-OFF mode of cooling, since moisture potential of the two rooms reaches an equalized state as a result of moisture diffusion. 2. It was recognized that changes in relative humidity did not show any significance in view of thermal comfort as was reported in the previous studies, while variations of both temperature and air velocity caused relatively large changes in the degree of thermal comfort. 3. In-door environment should be evaluated in terms of PPD instead of relative humidity commonly recognized as an important climatic variable particularly in warm and humid environments.

• 전기학회논문지P
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• 제61권1호
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• pp.55-58
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• 2012

By using EEG and HRV, subjects were estimated on their psychological and physiological reaction when reading psychrometric chart in 7 point century font, in an environmental test room in the condition of temperature 25[$^{\circ}C$], relative humidity 50[RH%], air current speed 0.02[m/sec], giving variation in illuminance to 0.1, 300, 600, 1000, 1300 and 1600[lux]. As a result, it was at 1300[lux] that absolute ${\alpha}$ wave, SMR, SDNN were most vitalized, and also both sides ${\alpha}$ wave asymmetry index, SEF50, HRT, stress and fatigue degree were at the lowest. It was found that a certain illuminance which minimizes psychological stress and fatigue degree while enhancing concentration and task achievement stably does exist.

• 한국건축시공학회지
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• 제7권3호
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• pp.107-113
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• 2007

This study is to investigate adhesive properties depending on the temperature, humidity, and freeze-thraw of the Steel plate adhesive strengthening method by the epoxy resin. The results are summarized as following. For the temperature variation, the debonding failure appear only after 1 cycle of temperature varoation because the coefficient of thermal expansion of the epoxy resin is comparatively large, and the bonding strength is decreased. The deformation properties and ultrasonic pulse velocity on each materials are similar until 4 cycles on the dry and moisture test. As the freeze-thraw test, the epoxy resin is degraded easily subjected to freeze-thaw cycle, comparatively easy, so the debonding failure may occur in short term because of the freeze-thaw repeatition.p

• 항공우주기술
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• 제9권2호
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• pp.98-104
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• 2010

대기 중의 수증기는 가스터빈엔진의 주요성능에 많은 영향을 끼친다. 습공기의 영향은 기온 및 기압이 높은 여름철 해면 고도, 높은 비행 마하수 그리고 낮은 엔진 회전수에서 이 더욱 두드러진다. 이러한 습공기 유입에 따른 가스터빈 엔진의 성능변화의 정도를 살펴보고자 가스터빈 시뮬레이션 프로그램(GSP)과 200lbf 급 초소형 터보제트 엔진의 고공환경 성능시험을 통해 습도가 엔진성능에 미치는 영향에 대하여 알아보았다. 고공환경 엔진시험을 통해, 건공기 유입에 비해 습공기 유입 시 순추력에서 2.826% 낮게, 비연료소모율에서 1.325% 높게 측정되었다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 추계학술발표회
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• pp.99-102
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• 2001

The soil-to-air fluxes of three PAHs(Phenanthrene, Pyrene, Benzo(a)pyrene) from a laboratory contaminated forest soil were investigated in experimental microcosms. The effects of soil temperature(45$^{\circ}C$, $25^{\circ}C$, 5$^{\circ}C$) and relative humidity(0%, 100%) were investigated according to existence of the humic layer(O layer) over the mineral layer(A layer). Volatilization flux experiments were carried out for a period of 96 hrs. The resulting PAHs volatilization fluxes from the different conditions were quantified and compared. In the mineral layer, highest volatilization flux among the individual PAHs was Phenanthrene >Pyrene> Benzo(a)pyrene on the conditions of 45 $^{\circ}C$, RH=100%. In the humic layer over the mineral layer, maximum volatilization flux was Phenanthrene on the condition of 45$^{\circ}C$, RH=0%. Results from flux experiments showed that volatilization fluxes of PAHs were dependent on soil temperature. Existance of humic layer over the mineral layer delayed transportation to the air of especially heaveir molecular PAHs. But, if humic layer is contained water sufficiently, it is possible that volatilization fluxes are enhanced by water convective flux according to variation of soil temperature and air relative humidity.