• 한국물환경학회지
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• 제20권6호
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• pp.641-646
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• 2004

Vehicle emissions from highway landuse include different pollutants such as heavy metals, oil and grease and particulates from fuels, brake pad wear and tire wear. Since highways are impervious and have high pollutant mass emissions from vehicular activity, it is considered as stormwater intensive landuses. Therefore this research was performed to understand the magnitude of first flush and to suggest the criteria of first flush for storm runoff management in highways. The fractions of washed-off mass are very high in first 30% of runoff volume, which suggests a definition of first flush. The washed-off mass stabilizes after 30% of the runoff volume and it is apparent that treatment capacity in the early part of a storm is more valuable than treatment capacity in the later part of the storm. Using the criteria of "high" first flush and "medium" first flush, as 50% of the mass in the first 30% of the volume, and 30 to 50% in the first 30% volume, respectively, more than 30% of the storms showed high first flush. A "first flush friendly" best management practice(BMP), meaning a BMP that can treat a high percentage or all of the initial flow, would be advantageous up to 80% of the events.

• 한국물환경학회지
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• 제25권6호
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• pp.943-950
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• 2009

Cadmium (Cd) adsorption onto the activated carbon containing hydroxyapatite (HAP) was investigated in batch experiments and response surface methodology (RSM) using the Box-Behnken methods were applied to the experimental results. Cd adsorption with different HAP mass ratio of from 10% to 30%. With more HAP, Cd was more adsorbed. These results suggest that the higher HAP mass causes an increase of the ion exchange potential of the HAP sorbent. Equilibrium experimental results from Cd adsorption was fitted to Langmuir and Freundlich isotherm models. Cd adsorption on HAP sorbent were found to follow the Freundlich isotherm model well in the initial adsorbate concentration range. Also, Cd adsorption was a function of the HAP mass ratio ($x_1$), initial Cd concentration ($x_2$), and initial pH ($x_3$) from the application of the RSM. Statistical results showed the order of significance of the independent variables to be initial Cd concentration > HAP mass ratio > initial pH.

• 설비공학논문집
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• 제5권1호
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• pp.1-9
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• 1993

Mass transfer coefficients were measured for water vapor absorption into a LiBr-Water solution of 60wt% flowing down an absorber of vertical tube type. The absorber is copper tube of 25mm inner diameter and 1000mm length. The film Reynolds number were varied in the range of 35~130. The solution is fed from the top of the pipe, and the conditions of solution are supercooled liquid and superheated liquid. As results, the flowrates of LiBr solution which takes peak value of average absorption mass flux exist. Mass transfer coefficients decrease with increasing the flowrate of LiBr solution, and the decrease rate in the case of supercooled liquid is large as compared with that in the case of superheated liquid. But the absorption rate of supercooled liquid is decidedly superior to that of superheated liquid.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1400-1405
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• 2004

Experimental study is performed to investigate the effect of heat load and operating temperature on the thermal performance of a heat pipe with screen mesh wick. The heat pipe was designed in 200 screen meshes, 500mm length and 12.7mm O.D tube of copper, water as working fluid(4.8g) and nitrogen as non-condensible gas(NCG). The heat pipe used in this study has evaporator, condenser and adiabatic section, respectively. Experimental data of axial wall temperature distribution is presented for heat transport capacity, the temperature of cooling water of condenser, inclination angle, and operating temperature. For the results from this study, it is found that, for the same charging mass of working fluid, the initial operating temperature and the overall wall temperatures of heat pipe are higher for NCG charging mass of $5.0{\times}10^{-6}kg$ and $3.4{\times}10^{-6}kg$, than that of $1.0{\times}10^{-6}kg$.

• 동의생리병리학회지
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• 제34권4호
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• pp.209-214
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• 2020

The association of cold-heat (CH) pattern and anthropometry/body composition has been suggested in that they are related to thermoregulation. We aimed to study the association of CH pattern and anthropometry/body composition. A total of 1479 individuals aged 50-80 years were included in the study, and their CH pattern were evaluated by a self-administered questionnaire. After adjustment for age and sex, the CH score were significantly correlated with weight, BMI (body mass index), body surface area, waist-hip ratio, fat free mass, body fat mass, body cell mass, intracellular water, extracellular water, and basal metabolic rate; however, the correlation coefficients were mostly low (0.15-0.24). The selected variables for predicting CH score were various according to the methods used for variable selection; however, the adjusted R-squared of the final models were all around 0.12. Thus the most parsimonious model could be the one that includes sex and BMI. In conclusion, various anthropometry and body composition indices were associated with CH pattern. Future studies are necessary to improve the performance of the prediction model.

• Ocean and Polar Research
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• 제44권3호
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• pp.191-207
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• 2022

Using the results of CTD casts made in Spring from 2017 to 2021, in this study we investigated the water mass distribution and occurrence of temperature inversion in the western seas of Jeju Island in spring. The distribution of water masses was characterized by cold and fresh water in the northwest and warm and saline water in the southeast, forming a strong thermohaline front running in the southwest-to-northeast direction. Strong temperature inversion mainly occurred in the frontal boundary when the cold water intrudes beneath the warm water at depths of 30-50 m. Analysis of the mixing ratio demonstrated that Jeju Warm Water is dominantly distributed in the western seas of Jeju Island, but its ratio can be modified depending on the southward extension of Yellow Sea Cold Water (YSCW). Results of in situ measurement showed that in 2020, the YSCW largely expanded to the western seas of Jeju Island, occupying approximately 40 % of the mixing ratio. Due to the expansion of YSCW, a strong thermohaline front was formed in the study area, thereby causing thick and strong temperature inversion. On the other hand, in 2018 the mixing ratio of YSCW was minimum (~18%) during the study period of 2017-2021, and thus a relatively weak frontal boundary was formed, without the occurrence of temperature inversion. The observational results also suggest that the interannual changes of water mass distribution and the associated temperature inversion in the western seas of Jeju Island are closely related with wind-driven Yellow Sea circulation in spring, which is the summer monsoon transition period.

• 한국농림기상학회지
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• 제14권1호
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• pp.39-44
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• 2012

본 연구는 1963년도에 식재된 낙엽송, 소나무, 리기테다소나무 조림지를 대상으로 셀룰로오스 분해와 토양 환경인자 사이의 관계를 구명하기 위해 수행하였다. 셀룰로오스 분해에 영향을 미칠 수 있는 토양온도, 토양 수분함량, 토양 pH, 토양 이산화탄소 방출량을 2006년 7월부터 10월까지 4개월 동안 측정하였다. 셀룰로오스 분해율은 리기테다소나무($6.5mg\;g^{-1}\;day^{-1}$), 소나무($6.2mg\;g^{-1}\;day^{-1}$), 낙엽송($6.1mg\;g^{-1}\;day^{-1}$) 순이었으나 수종간 유의적인 차이는 없었다(P > 0.05). 셀룰로오스 분해율은 20cm 깊이의 토양 온도와 양의 상관(소나무: r = 0.77, P < 0.05; 리기테다소나무: r = 0.59, P < 0.05; 낙엽송: r = 0.48, P < 0.05)을 보였으나, 토양 pH와는 음의 상관(소나무: r = -0.63, P < 0.05; 리기테다소나무: r = -0.47, P < 0.05; 낙엽송: r = -0.43, P < 0.05)이 있었다. 토양이산화탄소방출량과 셀룰로오스 분해율은 소나무(r = 0.46, P < 0.05), 낙엽송(r = 0.37, P < 0.05), 토양 수분함량과 셀룰로오스 분해율은 소나무(r = 0.53, P < 0.05)와 유의적인 양의 상관(P < 0.05)이 있었다. 본 연구 결과에 따르면 셀룰로오스 분해는 각기 다른 침엽 수종으로부터 발생하는 토양 환경요인에 의해 영향을 받는 것으로 나타났다.

• 한국대기환경학회지
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• 제20권6호
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• pp.803-810
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• 2004

Water contents in fine particles at Seoul and Gosan are estimated by using a gas/particle equilibrium model, SCAPE (Simulating Composition of Atmospheric Particles at Equilibrium). Also, sensitivity of particulate inorganic ionic concentrations on the total ionic species is estimated. Water content at Gosan is more sensitive to ambient relative humidity (RH) than Seoul. At both sites water content is most sensitive to sulfate concentration among sulfate, nitrate, and ammonium. Solid salts levels and compositions are also studied.

• 대한기계학회논문집B
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• 제20권10호
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• pp.3293-3303
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• 1996

Numerical analyses have been performed to estimate the absorption heat and mass transfer coefficients in absorption process of the LiBr aqueous solution and the total heat and mass transfer rates in a vertical tube absorber which is coolING ed by air. Axisymmetric cylindrical coordinate system was adopted to model the circular tube and the transport equations were solved by the finite volume method. Absorption behaviors of heat and mass transfer were analyzed through falling film of the LiBr aqueous solution contacted by water vapor in tube. Effects of film Reynolds number on heat and mass transfer coefficients have been also investigated. Especially, effects of tube diameter have been considered to observe the total heat and mass transfer rates through falling film along the tube. Based on the analysis it has been found that the total mass transfer rate increases rapidly in a region with low film Reynolds number(10 ~ 40) as the film Reynolds number increases, while decreases beyond that region. The total heat and mass transfer rates increase with increasing the tube diameter.

• 한국안전학회지
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• 제18권1호
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• pp.19-27
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• 2003

This paper presented an experimental modal analysis of clamped perforated rectangular plates submerged in water. The penetration of holes in the plates had a triangular pattern with P/D (pitch to diameter) 1.750, 2.125, 2.500, 3.000 and 3.750. The natural frequencies of the perforated plates in air were obtained by the Rayleigh-Ritz method and compared with the experimental results. Good agreement was obtained between the analytical solution and experimental result. The experimental results in water showed that the mode shapes are not sensitive to the depth of submergence. The natural frequencies were shown to decrease drastically once the perforated plates come in contact with water. However, the natural frequencies decrease with the depth of submergence until a certain depth is reached, and become the asymptotic values beyond this depth of submergence. The depth of submergence did not affect the damping ratio greatly.