• Journal of Wetlands Research
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• v.14 no.1
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• pp.11-20
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• 2012

The aim of this study is to accumulate the data about the roof-harvested rainwater quality characteristics for the better rainwater management. According to the results of rainwater quality indicators (pH, COD, TSS, T-N, T-P, $NH_4$-N, $NO_3$-N, enteric bacteria, heterotrophs, Pb, Cd, Cu), the rainwater qualities of the first flush of roof-harvested was the most polluted about 2 or 3 times (more than 100 times in microbial contamination) compared to the qualities of directly collected rainwater. In the first 10 min flush, over the 60% amounts of contaminant were released from the roof during 30 minute rainwater monitoring. Through statistical factor analysis, relatively close items(variables) can be categorized. It is expected that the continuous monitoring of the roof-harvested rainwater will help to design the safe and economical rainwater storage system in Korea.

• Current Research on Agriculture and Life Sciences
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• v.32 no.1
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• pp.30-33
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• 2014

A simulation model was developed to monitor food contamination during the ripening process of Kimchi on a factory scale. The cabbages were divided into three groups: control (without salt or red pepper), samples with added salt, and samples with added salt and red pepper. The processed Kimchi was left to ripen in a refrigerator at $4^{\circ}C$ and five frog heads (contaminant) left on the surface of the cabbages in each group. For the control, the contaminant exhibited a long life span of 10 days or more, however, for the samples with salt and samples with salt and red pepper, the contaminant showed a relatively short life span. In particular, for the processed Kimchi that included salt and red pepper, the life-span of the contaminant was dramatically decreased to around 3 days. Therefore, the present results suggest that the proposed simulation trial is suitable for monitoring contamination during Kimchi production. Moreover, since the contaminant could not survive more than 3 days, this suggests that the salt concentration in the Kimchi damaged the permeability of the skin and other tissue membranes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1308-1312
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• 2011

CCFL(Cold Cathode Fluorescent Lamp)for BLU of LCD and special lighting has been widely utilized. The removal of oxide film formed on electrode of CCFL in manufacturing process is required. In this pape Plasma treatment was carried out to remove the oxide film. To ensure the optimum process, the analysis of sheet resistance, XRD, AFM and solder test was conducted. A minimum sheet resistance and the maximum percentage of the solder coverage ratio were measured in optimal process conditions such as plasma power consumption 600W and processing time of 70 seconds. As the plasma treatment is confirmed to be due to removal of copper oxide, this process is expected to be used as a treatment of electrode for CCFL.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.181-184
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• 2003

Low Energy High flux Plasma Source인 Stationary Plasma thruster (SPT)를 이용하여 폴리이미드의 표면개질 후 접촉각과 표면에너지의 변화를 조사하고 접착력과의 관계를 조사하였다. 이온에너지는 180 eV - 200 eV, 이온전류 밀도는 수백 ${\mu}A/cm^2$, 이온선량은 $5\times10^{15}/cm^2$부터, $10\times^{18}/cm^2$로 $Ar^+,\;N_2^+,\;O_2^+$를 이온 주입시켰다. 표면 처리된 폴리이미드에 대한 접촉각 변화는 dual contact anglemeter로 증류수와 에틸렌글리콜을 이용하여 측정하였고, 표면에너지의 변화량을 구하였다. 접촉각의 변화는 아르곤 이온의 경우는 최저 $35^{\circ}$, 질소와 산소의 경우 $1\times10^{17}/cm^2$에서 각각 $14^{\circ},\;10^{\circ}$정도의 전촉각을 보였으며, $5\times10^{17}/cm^2$이상에서는 측정하기 불가능하였다. 산소 이온빔으로 처리된 PI의 표면을 x-ray photoelectron spectroscopy를 통하여 측정하여본 결과, 친수성기가 많이 형성되었음을 확인할 수 있었다. 접촉각 측정으르부터 PI의 표변에너지는 42.1 mN/m에서 아르곤 이온빔의 처리 시 65.2 mN/m로 산소 이온빔의 처리 시 81.2 mN/m로 각각 1.5배, 1.9배 정도 증대하였다. 산소 이온빔으로 처리된 PI 표면위에 스퍼터링으로 300 nm 정도의 clad layer 형성 후 $20{\mu}m$ 정도의 구리 전기 도금막을 형성하여, peel 강도를 측정한 결과 0.79 kg/cm의 강도를 얻을 수 있었다.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.169-174
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• 2001

Low cycle fatigue tests are performed on high strength low alloy steels that be developed for submarine material. The relation between absorbed plastic strain energy and numbers of cycle to failure is examined in order to predict the low cycle fatigue life of structural steels by using plastic strain energy method. The cyclic properties are determined by a least square fit techniques. The life predicted by the plastic strain energy method is found to coincide with experiment data and results obtained from the Coffin-Manson method. Also the cyclic behavior of structural steels is characterized by cyclic softening with increasing number of cycle at room temperature. Especially, low cycle fatigue characteristics and microstructural changes of structural steels are investigated according to changing tempering temperatures. In the case of PFS steels, the $\varepsilon$-Cu is formed in 550C of tempering temperature and enhances the low cycle fatigue properties.

• Korean Journal of Materials Research
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• v.30 no.1
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• pp.44-49
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• 2020

The effect of intercritical annealing temperature on the microstructure and mechanical properties of Fe-9Mn-0.2C-3Al-0.5Si medium manganese steels containing Cu and Ni is investigated in this study. Six kinds of medium manganese steels are fabricated by varying the chemical composition and intercritical annealing temperature. Hardness and tensile tests are performed to examine the correlation of microstructure and mechanical properties for the intercritical annealed medium manganese steels containing Cu and Ni. The microstructures of all the steels are composed mostly of lath ferrite, reverted austenite and cementite, regardless of annealing temperature. The room-temperature tensile test results show that the yield and tensile strengths decrease with increasing intercritical annealing temperature due to higher volume fraction and larger thickness of reverted austenite. On the other hand, total and uniform elongations, and strain hardening exponent increase due to higher dislocation density because transformation-induced plasticity is promoted with increasing annealing temperature by reduction in reverted austenite stability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.873-877
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• 2005

The burr of micro drilling and micro cutting on thin metal film is a major obstacle to mass production for micro PCB boards in micro technologies of personal computing and telecom explosion. As the burr affects on the assembling process, it is necessary to study continuously on control or elimination of the burr. In order to get higher valued products, it is also needed to competitive techniques with the high resolution. In this paper, we studied experimentally the burr generation that when it is processed on the copper foil by laser in micro-hole machining. Unlike mechanical machining the burr produced on substrate is a resultants of melt and re-solidification of a melten metal which was heated and treated by laser. And higher laser energy increases the size of burr. Therefor in micro-drilling with laser, it is difficult to reduce the effects of burr for very thin metal sheets. We investigated the stale of the burr and analyzed the laser ablation Cu micro machining with respect to laser intensity and processing time.

• Journal of the Korean Solar Energy Society
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• v.35 no.1
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• pp.29-34
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• 2015

The photovoltaic ribbon attached the flux reduces the solar module manufacturing process and the pollution. This paper presents an analytical method for solving the continuous flux drying system of photovoltaic ribbon. Also, some experiments of the drying of photovoltaic ribbon are carried out in order to design the drying system. Numerical results indicate the air temperature, the air velocity, the air pressure and the timewise temperature variation of ribbon during drying process. In case of the drier process length is short, 400mm, the photovoltaic ribbon is wet. Thus, another study of drying system is necessary to improve the drying ability. As a result, multi-stage drier system is proposed and shown to be good drying ability.

• Journal of the Korean institute of surface engineering
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• v.54 no.3
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• pp.124-132
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• 2021

Graphene which grown on the cobalt or nickel sputtered copper foil depending on the annealing time was studied. Graphene on the copper foil grown by chemical vapor deposition was compared to those on cobalt or nickel sputtered copper foil by using a RF (Radio Frequency) magnetron sputtering at room temperature. FLG(few-layer graphene) was identified independent of substrates by Raman and X-Ray Photoelectron Spectroscopy analyses. On copper foil, size and area fraction of the graphene growth increased until 30 minutes annealing and then didn't changed. Comparing to that, graphene on the cobalt refined till 50 minutes annealing, after then the effect disappeared which means a similar shape to that on copper foil. On nickel the graphene refined irrespective of annealing time that is possibly because of the complete solid solution of nickel with copper.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.3
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• pp.190-198
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• 2008

There is an increasing concern over heavy metal contamination of paddy soils and the subsequent translocation of heavy metals to rice. Objective is to monitor the status and long-term trend of heavy metal contamination in paddy soils, periodically. In 2007 survey, the average concentrations of As(arsenic), Cd(cadmium), Cu(copper), Ni(nickel), Pb(lead), and Zn(zinc) in 2,010 paddy soils nationwide were 0.87, 0.08, 3.33, 1.19, 4.95 and $4.67mg\;kg^{-1}$, respectively. Few sites, which were contaminated by As in 2003 and 2007 survey and by Ni in 1999 and 2007 survey, were over the threshold level for soil contamination designated by the Soil Environmental Conservation Act in Korea. Long-term change was shown that As, Ni, and Zn were gradually increased whereas Cd and Cu were decreased. In the distribution of extractable heavy metal contents, the modes of each heavy metal content were similar with the average contents of each heavy metals. Mean value of heavy metals except copper in paddy soils was higher than median value. It means that the downward distribution of heavy metal content in paddy rice was shown against normal distribution.