• 한국환경보건학회지
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• 제39권1호
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• pp.56-70
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• 2013

Objectives: This paper aims to investigate the seasonal deposition characteristics of water-soluble ion species by comparing the deposition amount of two samples taken according to different sampling methods of deposition for ambient aerosol such as gases and particulate matters. Methods: Deposition samples were collected using two deposition gauges in the downtown area of Iksan City over approximately two weeks of each season in 2004. The type of deposition gauges consisted of two different sampling methods known as dry gauge and a wet gauge. The dry gauge was empty and used a dry PE bottle with an inlet diameter of 9.6 cm. Before the beginning of each deposition sampling, a volume of 30-50 ml distilled ionized water was added to the wet gauge to wet the bottom during the sampling period. Deposition samples were measured twice per day and analyzed for inorganic water-soluble ion species using ion chromatography. Results: The daily deposition amounts of all measured ions in the dry gauge and the wet gauge showed a significant increase when precipitation occurred, having no difference of deposition amount between in the wet gauge and in the dry gauge. By excluding two samples from rainy days during the sampling period, the mean daily deposition of all ions in dry gauge and wet gauge were $6.58mg/m^2/day$ and $18.16mg/m^2/day$, respectively. The mean deposition amounts of each ion species were higher in the wet gauge than in the dry gauge because of the surface difference of the sampling gauge, especially for $NH_4{^+}$ and ${SO_4}^{2-}$. The mean deposition amounts of $NH_4{^+}$ and ${SO_4}^{2-}$ in the wet gauge were found to be about 15.4 times and 5.2 times higher than that in dry gauge, with a pronounced difference between spring and summer, while the remaining ion species were 1.1-2.0 times higher in the wet gauge than in the dry gauge. Dominant species in the dry gauge were $Ca^{2+}$ and $NO_3{^-}$, accounting for 36.4% and 18.1% of the total ion deposition, whereas those in the wet gauge were $NH_4{^+}$ and ${SO_4}^{2-}$, accounting for 32.5% and 25.0% of the total ion deposition, respectively. Conclusion: The seasonal differences in deposition amounts of water-soluble ion species in ambient aerosol depending on the two types of different sampling methods were identified. This suggests that the removal of ambient aerosol is strongly influenced by the weather conditions of each season as well as the condition of earth's surface, such as dry ground and water.

• 한국환경보건학회지
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• 제32권4호
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• pp.359-372
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• 2006

In order to investigate the daily deposition characteristics of water-soluble inorganic components in airborne deposit on the Iksan, deposition samples were collected using a deposition gauge from October 16 to November 1, 2004. Deposition samples were collected using two different sampling gauges, a dry gauge and a wet gauge, respectively. To get wet the bottom of wet gauge during the sampling period, the volume of $30{\sim}50ml$ distilled ionized water was added in a wet gauge before the beginning of each deposition sampling. Deposition samples were collected twice a day and analyzed for inorganic water-soluble anions ($Cl^-,\;{NO_3}^-,\;{SO_4}^{2-}$) and cations (${NH_4}^+,\;Na^+,\;K^+,\;Mg^{2+},\;Ca^{2+}$) using ion chromatography. Qualify control and quality assurance of analytical data were checked by the data obtained from reinjection of standard solution, Dionex cross check standard solutions, and random several deposition samples, and measured data was estimated to be reliable. Considering the deposition sample volume, the sampling time, the surface area of sampling container, and the ion concentration measured, the daily deposition amounts for measured ions were calculated in $mg/m^2$. The total daily deposition amounts of all measured ions for dry and wet gauge were $7.5{\pm}2.8$ and $17.7{\pm}4.2mg/m^2$, respectively. A significant increase in deposition amount during rainfall days was observed for both wet gauge and dry gauge, having no difference of deposition amount between in wet gauge and in dry gauge. The mean deposition of all ions measured in this study were higher in wet gauge than in dry gauge because of the surface difference of the sampling container, especially for ${NH_4}^+\;and\;{SO_4}^{2-}$. The mean deposition amounts of ${NH_4}^+\;and\;{SO_4}^{2-}$ in wet gauge were found to be about 10 times and 3 times higher than those in dry gauge, while the rest of the chemical species were equal or a little higher in wet gauge than in dry gauge. Dominant species in dry gauge were ${NO_3}^-\;and\;Ca^{2+}$, accounting for 21% and 28% of the total ion deposition, whereas those in wet gauge were ${SO_4}^{2-}\;and\;{NH_4}^+$, accounting for 19% and 41% of the total ion deposition, respectively.

• 한국환경보건학회지
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• 제20권2호
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• pp.39-54
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• 1994

Dry and wet deposition samples were continuously collected by deposit gauge. In Bulkwang area of Seoul and Kanghwa in west coastal area of Korea. In order to evaluate the level of air pollution and its chemical composition, Bulkwang area located in Seoul and Kanghwa in west coastal area were chosen for sampling site. dry deposition concentrations, pH, electric conductivity and water soluble ion concentrations of deposit gauge were analysed. The results of comparison between urban area and coastal area were summarized as follows. Mean concentrations of dry deposition in Bulkwang was 2.807 ton/km$^2$/month (range: 5.171~1.128 ton/km$^2$/month) while that in Kanghwa was 1.990 ton/km$^2$/month (range: 3.358 ~ 1.084 ton/km$^2$/month), which showed a significant difference between two areas. The rainfall during the period from June to September in 1990 recorded 1859.7 mm which was 78.8% of its mean amount in Seoul, and 1846.9 mm which was 81.6% that of Kanghwa. In Bulkwang area, correlation coefficients of deposit chemical composition were 0.95 for SO$_4^{-2}$ and Na$^+$, 0.94 for SO$_4^{-2}$ and NH$_4^+$, 0.93 for CI$^-$ and NH$_4^+$ and 0.85 for Cl$^-$ and Ca$^{2+}$, respectively. Then, the results indicate that sulfates such as $Na_2SO_4$, $(NH_4)_2SO_4$, and CaSO$_4$ were the major chemical state of deposit. In Kanghwa area, it was considered that NaCl, $NH_4NO_3$, NaNO$_3$, and $Ca(NO_3)_2$ were the major chemical state of deposit.

• Journal of Radiation Protection and Research
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• 제22권4호
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• pp.289-298
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• 1997

중성자 수분함량 측정기의 개발에 있어서 중성자 계측값과 흙속의 수분함량에 대한 관계식을 유도하기 위해서는 공시체 제작 등의 많은 실험을 통해 유도한 교정식이 필요하다. 또한 공시체 제작 및 측정실험의 통계적 오차를 줄이기 위해서는 많은 시간과 노력이 필요하다. 하지만 몬테카를로방법을 사용한 전산코드를 이용하여 수행할 경우 시간과 노력을 줄일 수 있을 뿐만 아니라, 보다 일반적인 흙에 대한 교정식을 얻을 수 있다. 본 연구에서는 중성자의 수송문제를 계산하는데 유용한 MCNP4A 전산코드를 이용하여 실제 실험을 모사하였다. 또한 모사결과를 공시체를 제작하여 실험한 결과와 비교하였다. 비교결과 실제실험의 결과와 모사 범위 내에서 일치함을 알 수 있었다. 중성자 수분함량 측정기의 교정식 도출 및 교정상수를 결정하기 위해 적용할 수 있음을 알 수 있었다. 또한 수분함량 측정기의 계측값에 영향을 미치는 인자중의 하나인 흙의 건조밀도 변화에 대한 영향을 살펴보았다.

• 센서학회지
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• 제16권2호
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• pp.126-131
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• 2007

In this paper, we fabricated piezoresistive pressure sensor with dry etching technology which used ICP-RIE (inductively coupled plasma reactive ion etching) and etching delay technology which used SOI (silicon-on-insulator). Structure of the fabricated pressure sensor shows a square diaphragm connected to a frame which was vertically fabricated by dry etching process and a single-element four-terminal gauge arranged at diaphragm edge. Sensitivity of the fabricated sensor was about 3.5 mV/V kPa at 1 kPa full-scale. Measurable resolution of the sensor was not exceeding 20 Pa. The nonlinearity of the fabricated pressure sensor was less than 0.5 %F.S.O. at 1 kPa full-scale.

• 한국정밀공학회지
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• 제33권7호
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• pp.541-549
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• 2016

Rolling contact fatigue and wear on rails are inevitable in railway operations due to excessive wheel-rail contact stress. The wear is influenced by vehicle speed, contact pressure, environmental conditions, and many other factors. Speeding on a curved track causes many problems such as wear on the gauge of the rail and rolling contact fatigue. Managing environmental conditions can reduce problems on the wheel and rail interface. In this study, the wear characteristics of wheel and rail materials were investigated by twin-disc testing using various parameters. The results of the wear test indicated that the wear rate under dry conditions was larger than that under wet conditions. We found that contact fatigue damage occurred on the rail in dry conditions, however, the surface of the specimen under water remained smooth. Also, the friction coefficient in dry conditions was larger than in wet conditions.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.275-275
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• 2021

A fixed Z-R relationship approach, such as the Marshall-Palmer relationship, for an entire year and for different seasons can be problematic in cases where the relationship varies spatially and temporally throughout a region. From this perspective, this study explores the use of long-term radar reflectivity for South Korea to obtain a nationwide calibrated Z-R relationship and the associated uncertainties within a Bayesian regression framework. This study also investigates seasonal differences in the Z-R relationship and their roles in reducing systematic error. Distinct differences in the Z-R parameters in space are identified, and more importantly, an inverse relationship between the parameters is clearly identified with distinct regimes based on the seasons. A spatially structured pattern in the parameters exists, particularly parameter α for the wet season and parameter β for the dry season. A pronounced region of high values during the wet and dry seasons may be partially associated with storm movements in that season. Finally, the radar rainfall estimates through the calibrated Z-R relationship are compared with the existing Z-R relationships for estimating stratiform rainfall and convective rainfall. Overall, the radar rainfall fields based on the proposed modeling procedure are similar to the observed rainfall fields, whereas the radar rainfall fields obtained from the existing Marshall-Palmer Z-R relationship show a systematic underestimation. The obtained Z-R relationships are validated by testing the predictions on unseen radar-gauge pairs in the year 2018, in the context of cross-validation. The cross-validation results are largely similar to those in the calibration process, suggesting that the derived Z-R relationships fit the radar-gauge pairs reasonably well.

• 한국제4기학회지
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• 제14권2호
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• pp.87-99
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• 2000

설악산에서 작성된 8개 지역 연륜연대기 중 강수량 복원에 적합한 대승폭포 인근 2개 지역(해발고 700~900m)의 연륜연대기를 이용하여 253년간 (A.D. 1746~A.D. 1998)의 5월~6월 총강수량을 복원하였다. 1765~1800년(최장 가뭄), 1835~1845년, 1890~1910년, 1920~1940년, 1980~1995년이 건조기로 나타났으며, 1810~1830년, 1860~1890년, 1950~1970년이 습윤한 시기로 나타났다. 장기간으로 보았을 때, 18세기 후반기는 건조한 기간이었으며, 19세기의 5월~6월 총강수량이 250mm로 20세기의 231mm보다 많아 19세기가 20세기보다 상대적으로 습윤하였음을 알 수 있었다. 강수량 변화폭이 19세기가 20세기보다 큰 것으로 관찰되었다. 전 기간에 걸친 주요한 건습 주기는 단기간은 3년, 장기간은 60~80년으로 조사되었다. 서울지방의 측우기 자료와는 1800년대 초를 제외하곤 대체로 일치하였다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.236-240
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• 2009

Dry wall using steel stud has the advantage of possibility to install various building, so it used to many buildings inside and outside of the country very rapidly. Though Light gauge steel framed housing offers many advantages to the consumer and the builder, the use of steel studs in wall system cause thermal problems such as thermal performance and pattern staing on walls. The present study has been conducted to observe effect of stud by the shape, and two kind of stud is made for this test to compare thermal performance. The test was conducted by setting those stud on the chamber and heating them. As the results of test and photograping by using TVS, there was temperature gap of each stud, and surface temperature of each section was appeared differently due to shape of stud delaying thermal bridge.

• 한국농공학회지
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• 제26권4호
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• pp.37-51
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• 1984

The purpose of this study is to find out the determination method of designed duty of water in the rice fields through the comparison of the net unit duty of water at the late reduction division to heading stage with that at the planting stage. The data used for analysing this problem are the data of precipitation and gauge evaporation observed by Cheong-ju Meterological Center, the coefficient of evapotranspiration by College of Agriculture, Chung Buk University and the data of transplanting progressing in Boun area. The results obtained from this analysis are summarized as follows. 1.The occurring year of 1/10 probability value for available precipitation, gauge evaporation and mean maximum daily evapotranspiration during growing season is the year of 1977. 2.The 1/10 probability values of mean maximum evapotranspiration per day under the production rate of 1, 400kg/l0a and 1, 500kg/10a based on the weight of dry matters are 9. 2mm/day and 9. 6mm/day, respectively. 3.The net unit duty of water required in the fields that the maximum planting rate exists is more than the one in the fields that the planting rate is uniform in the planting stage. 4.The determination of net unit duty of water in the late reduction division to heading stage or the planting stage depends upon the daily evapotranspiration and percolation rate in the late reduction division to heading stage or the water depth required for planting and daily consumptive use of water after planting at the planting stage. Therefore the use of figure 5-(1) to figure 5-(6) can easily make the determination of the designed net unit duty of water out of above two kinds of net unit duty of water.