• 한국재료학회지
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• 제28권4호
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• pp.201-207
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• 2018

Infrared(IR) heating has many advantages, such as energy efficiency, reduced heating time, cleanliness, equipment compactness, high drying rate and easy automation. These features of IR heating provide widely industrial applications, such as surface heat treatment in semiconductor fabrication, thermoforming of polymers, drying and disinfection of food products, heating to metal forging, and drying of wet materials. In this study, the characteristics of a protected gold mirror were examined by spectrophotometer and the lifetime of the coating layers were evaluated by a cross-cutting method and salt spray test. The effects of manufacturing conditions on the protected gold mirror were seen and remedies for these effects were noted in order to improve the properties of the protected gold mirror in the drying process. The reflectance and lifetime of the protected gold mirror was influenced by manufacturing conditions, such as surface roughness and forming conditions of the anti-oxide layer, the adhesion layer, the reflecting layer and the protection layer. The results of this study showed that the protected gold mirror manufactured using a buffing method for pre-treatment resulted in the most effective reflectance. In addition, $Al_2O_3$ coating on an Al substrate as an anti-oxide layer was more effective than the anodizing process in the test of reflectance. Furthermore, the protected gold mirror manufactured by layers forming of various materials resulted in the most effective reflectance and lifetime when coated with $Al_2O_3$ as the anti-oxide layer, coated Cr as the adhesion layer, and coated $MgF_2$ as the protection layer.

• 한국대기환경학회지
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• 제19권6호
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• pp.701-717
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• 2003

The objective of this study was to extensively estimate the air quality trends of the study area by surveying con-centration trends in months or seasons, after analyzing the mass concentration of PM-10 samples and the inorganic lements, ion, and total carbon in PM-10. Also, the study introduced to apply the PMF (Positive Matrix Factoriza-tion) model that is useful when absence of the source profile. Thus the model was thought to be suitable in Korea that often has few information about pollution sources. After obtaining results from the PMF modeling, the existing sources at the study area were qualitatively identified The PM-10 particles collected on quartz fiber filters by a PM-10 high-vol air sampler for 3 years (Mar. 1999∼Dec.2001) in Kyung Hee University. The 25 chemical species (Al, Mn, Ti, V, Cr, Fe, Ni, Cu, Zn, As, Se, Cd, Ba, Ce, Pb, Si, N $a^{#}$, N $H_4$$^{+}$, $K^{+}$, $Mg^{2+}$, $Ca^{2+}$, C $l^{[-10]}$ , N $O_3$$^{[-10]}$ , S $O_4$$^{2-}$, TC) were analyzed by ICP-AES, IC, and EA after executing proper pre - treatments of each sample filter. The PMF model was intensively applied to estimate the quantitative contribution of air pollution sources based on the chemical information (128 samples and 25 chemical species). Through a case study of the PMF modeling for the PM-10 aerosols. the total of 11 factors were determined. The multiple linear regression analysis between the observed PM-10 mass concentration and the estimated G matrix had been performed following the FPEAK test. Finally the regression analysis provided source profiles (scaled F matrix). So, 11 sources were qualitatively identified, such as secondary aerosol related source, soil related source, waste incineration source, field burning source, fossil fuel combustion source, industry related source, motor vehicle source, oil/coal combustion source, non-ferrous metal source, and aged sea- salt source, respectively.ively.y.

• 한국농공학회논문집
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• 제59권3호
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• pp.1-10
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• 2017

The aim of this study is to investigate the chemical properties and heavy metal concentration of soils in conventional and organic paddy. We sampled and analyzed topsoil (0~15 cm) and subsoil (15~30 cm) of conventional and organic paddy fields in Yongin and Anseong, South Korea. The statistical significance between groups was determined by Duncan's multiple range test and correlation between soil properties was also analyzed. The results show that organic matter (OM) and T-N of conventional paddy soil were higher than those of organic paddy soil. However, higher T-P concentration was observed in organic paddy soil than conventional paddy soil. As, Pb, and Zn concentration in organic paddy soil were statistically lower than those in conventional paddy soil. The couple of water content (WC) & As, OM & T-N, T-P & $P_2O_5$, T-P & Zn, $P_2O_5$ & Zn, and Cr & Ni had a good positive correlation but the couple of WC & T-P, WC & Zn, T-P & As, and As & Zn had a strong negative correlation. It can be concluded that organic farming is beneficial to soil environment by reducing the amounts of organic matter, T-N, As, Pb, and Zn concentration in paddy soil when compared to conventional farming.

• 한국환경복원기술학회지
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• 제14권3호
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• pp.15-32
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• 2011

This study was carried out to investigate the soil characteristics and propose the management for the Monument Beobsoo Marsh, Korea. The soil properties of O.M, $Ca^{2+}$, $Na^+$ and CEC were higher and the soil properties of pH_{1:5}$ and $P_2O_5$ were lower the studied sites than other marsh sites in Korea. Although the Heavy metals such as Pb, Hg, Cd, Cu, Zn, Cr and As were lower compare to the safety standard of soil pollution in Korea, the overall conservation management plan based on long-term monitoring should be considered just because it varied by the point and non-point source pollution within the studied marsh. The source of water pollution varied due to non-point polluting origins such as sewage inlet, degraded terrain for agriculture, fishing sites, sites of removed water grasses, pesticides, chemical fertilizers, as well as fallen leaves. The creation of an artificial marsh is recommended due to the soil environment of the studied sites may be changed owing to the accumulated contaminants from the sources of both of point or non-point contaminants. The establishment of the zones of core, buffer and transition which is basic management structure of the UNESCO MaB could be applied to manage the studied site. Simultaneously the promotion of voluntary participation and education of the local residents are needed.

• Corrosion Science and Technology
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• 제11권3호
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• pp.96-102
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• 2012

0.1 M NaOH 용액에 PbO첨가양이 증가함에 따라 Alloy 600에 형성되는 산화막의 부동태 피막 특성이 열화되었다. 또한 뚜렷한 2중층 구조의 산화막이 점차 사라지고, 산화막내 존재하는 납의 양이 증가하였다. 산화막 내부 납의 양이 증가함에 따라 산화막 내부 니켈의 결핍이 점차 커졌다. 납에 의해 산화막의 부동태 특성이 약화됨에 따라, 응력부식균열 저항성 또한 급감하였을 것으로 판단된다.

• 공업화학
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• 제9권5호
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• pp.619-623
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• 1998

불화된 금속 산화물 촉매상에서 이염화메탄을 불화하여 이불화메탄을 합성하는 연구를 하였다. 실험 변수는 반응온도, HF/DCM (dichloromethane) 몰비, 접촉시간 그리고 촉매의 형태이었다. 촉매의 성능은 불화된 알루미나 보다는 크롬이 담지된 불화된 알루미나가 우수하였으며 크롬을 담지한 촉매에서 전처리 하지 않은 경우가 수소와 공기 분위기로 소성처리한 경우보다 더욱 우수하였다. 최적 반응 조건은 반응온도 $340^{\circ}C$, HF/DCM 몰비 5이상 그리고 접촉시간 20 초 이상이었다. 이들 조건에서 얻은 이불화메탄의 최대 수율은 80% 이상이었다. 특히 반응시간이 8시간까지 촉매의 활성 감소나 이불화메탄의 선택성의 감소가 나타나지 않았다.

• 한국표면공학회지
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• 제40권4호
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• pp.175-179
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• 2007

An Fe-Ni-Co based superalloy Incoloy 909 (Incoloy 909) has been used for gas turbine engine component material. This alloy is susceptible to high temperature oxidation and corrosion because of the absence of corrosion resistant Cr. For the improvement of durability of the component of Incoloy 909 aluminizing-chromate coating by pack cementation process has been investigated at relatively low temperature of about $550^{\circ}C$ to protect the surface microstructure and properties of Incoloy 909 substrate. As a previous study to aluminizing-chromate coating by pack cementation of Incoloy 909, the optimal aluminizing process has been investigated. The size effects of source Al powder and inert filler $Al_O_3$ powder and activator selection have been studied. And the dependence of coating growth rate on aluminizing temperature and time has also been studied. The optimal aluminizing process for the coating growth rate is that the mixing ratio of source Al powder, activator $NH_4Cl$ and filler $Al_O_3$ are 80%, 1% and 19% respectively at aluminizing temperature $552^{\circ}C$ and time 20 hours.

• 한국산업보건학회지
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• 제24권4호
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• pp.547-555
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• 2014

Objective: This study was conducted to investigate the association between subjective distress symptoms and argon welding among workers in Gyeongnam Province shipyard. Method: 31 argon and 29 non-argon welding workers were selected as study subjects in order to measure concentrations of personal dust, welding fumes and other hazardous materials such as ZnO, Pb, Cr, FeO, MnO, Cu, Ni, $TiO_2$, MgO, NO, $NO_2$, $O_3$, $O_2$, $CO_2$, CO and Ar. An interviewer-administered questionnaire survey was also performed on the same subjects. The items queried were as follows: age, height, weight, working duration, welding time, welding rod amounts used, drinking, smoking, and rate of subjective distress symptoms including headache and other symptoms such as fever, vomiting and nausea, metal fume fever, dizziness, tingling sensations, difficulty in breathing, memory loss, sleep disorders, emotional disturbance, hearing loss, hand tremors, visual impairment, neural abnormality, allergic reaction, runny nose and stuffiness, rhinitis, and suffocation. Statistical analysis was performed using SPSS software, version 18. Data are expressed as the mean ${\pm}SD$. An ${\chi}^2$-test and a normality test using a Shapiro wilk test were performed for the above variables. Logistic regression analysis was also conducted to identify the factors that affect the total score for subjective distress symptoms. Result: An association was shown between welding type (argon or non-argon welding) and the total score for subjective distress symptoms. Among the rate of complaining of subjective distress symptoms, vomiting and nausea, difficulty breathing, and allergic reactions were all significantly higher in the argon welding group. Only the concentration of dust and welding fumes was shown to be distributed normally after natural log transformation. According to logistic regression analysis, the correlations of working duration and welding type (argon or non-argon) between the total score of subjective distress symptoms were found to be statistically significant (p=0.041, p=0.049, respectively). Conclusion: Our results suggest that argon welding could cause subjective distress symptoms in shipyard workers.

• 한국토양비료학회지
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• 제43권5호
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• pp.590-595
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• 2010

토양오염 방지사업에 의해 복원이 완료된 지역인 밀양시 구운동광산의 오염원인 잔존 광미 퇴적지의 광미와 주변 농경지에 대한 오염형태를 조사하여 환경 복원의 기초 자료를 얻고자 수행하게 되었다. 본 연구 대상지는 경남 밀양시 무안면 마흘리 구운동 광산 주변 수계 및 토양으로 조사지의 지질은 신라통 안산암질이며 광산의 광상은 함유 황광으로 주 채굴금속은 금, 은, 동, 납, 아연이었으며, 잔존 광미 퇴적지의 광미와 주변 농경지의 중금속을 분석하였다. 광구 직하류 휴경논 표토 (0-16 cm)의 화학성은 pH는 4.3-4.4내외, 치환성석회 및 고토함량은 각각 0.2 및 0.04 $cmol_c\;kg^{-1}$ 인 반면 토심이 깊어질수록 높아졌다. 광구수 및 광미 적치장 유출수의 직접 영향은 받는 최상류 퇴적토양(SI)의 0.1N HCl 가용성 Cu, Cd, Pb, Cr 및 Ni의 함량은 각각 97, 0.6, 197, 0.28 및 0.12 mg $kg^{-1}$이었고, 최하류 논 (SIII)의 경우 Cu 25, Cd 2.8, Pb 16.7, Cr 0.17 및 Ni 0.44 mg $kg^{-1}$이었다. 휴경지 논 토양 토심별 중금속 함량은 Cr, Pb, Cu는 토심 16 cm 상부에서, Cd, Ni는 토심 16-60 cm 부위에서 높은 분포특성을 보였다.

• 자원환경지질
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• 제32권6호
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• pp.611-631
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• 1999

Enviromental geochemisty and heary metal contamination at the Kongjueil mine creek were underaken on the basis of physicohemical properties and mineralogy for various kinds of water (surface, mine and ground water),soil, precipitate and sediment collected of April and December in 1998. Hydrgeochemical composition of the water samples are characterized by relatively significant enricant of Ca+Na, alkiali ions $NO_3$ and Cl inground and surfore water, wheras the mine waters are relatively eneripheral water of the mining creek have the characteristics of the (Ca+Mg)-$(HCO_3+SO_4)$type. The pH of the mine water is high acidity (3.24)and high EC (613$\mu$S/cm)compared with those of surface and ground water. The range of $\delta$D and $\delta^{18}O$ values (relative to SMOW) in the waters are shpwn in -50.2 to -61.6% and -7.0 to -8.6$\textperthousand$(d value=5.8 to 8.7). Using computer program, saturation index of albite, calcite, dolomite in mine water are nearly saturated. The gibbiste, kaolinite and smectite are superaturated in the surface and ground water, respectively. Calculated water-mineral reaction and stabilities suggest that weathing of silicate minerals may be stable kaolinite owing to the continuous water-rock reaction. Geochemical modeling showed that mostly toxic heavy metals may exist larfely in the from of metal-sulfate $(MSO_4\;^2)$and free metal $(M^{2+})$ in nmine water. These metals in the ground and surface water could be formed of $CO_3$ and OH complex ions. The average enrichment indices of water samples are 2.72 of the groundwater, 2.26 of the surface water and 14.15 of the acid mine water, normalizing by surface water composition at the non-mining creek, repectively. Characteristics of some major, minor and rate earth elements (Al/Na, K/Na, V/Ni, Cr/V, Ni/Co, La/Ce, Th/Yb, $La_N/Yb_N$, Co/Th, La/Sc and Sc/Th) in soil and sediment are revealed a narrow range and homogeneous compositions may be explained by acidic to intermediate igneous rocks. And these suggested that sediment source of host granitic gneiss colud be due to rocks of high grade metamorphism originated by sedimentary rocks. Maximum concentrations of environmentally toxic elements in sediment and soil are Fe=53.80 wt.% As=660, Cd=4, Cr=175, Cu=158, Mn=1010, Pb=2933, Sb=4 and Zn=3740 ppm, and extremely high concentrations are found are found in the subsurface soil near the ore dump and precipitates. Normalizing by composition of host granitic gneiss, the average enerichment indices are 3.72 of the sediments, 3.48 of the soils, 10.40 of the precipitates of acid mine drainage and 6.25 of the soils near the main adit. The level of enerichment was very severe in mining drainage sediments, while it was not so great in the soils. mineral composition of soil and sediment near the mining area were partly variable being composed of quartz, mica, feldspar, chlorite, vermiculite, bethierin and clay minerals. reddish variable being composed of quartz, mica, feldspar, chlorite, vermiculite, bethierin and clay minerals. Reddish brown precipitation mineral in the acid mine drainage identifies by schwertmanite. From the separated mineralgy, soil and sediment are composed of some pyrite, arsenopyite, chalcopyrite, sphalerite, galena, malachite, goethite and various kinds of hydroxied minerals.