• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.21-27
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• 2009

Resins were synthesized by mixing 1-aza-15-crown-5 macrocyclic ligand attached to styrene (a hazardous material) divinylbenzene (DVB) copolymer with crosslink of 1％, 2％, 5％ and 20％ by a substitution reaction. The characteristic of these resins was confirmed by the content of chlorine, element analysis, thermogravimetric analysis (TGA), surface area (BET), and IR-spectroscopy. The effects of pH, time, dielectric constant of solvents and crosslink on adsorption of metal ions by the synthetic resin adsorbent were investigated. The metal ion was showed a fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order of uranium ($UO_2^{2+}$) > manganese ($Mn^{2+}$) > praseodymium ($Pr^{3+}$). The adsorption was in the order of 1％, 2％, 5％, and 20％ crosslink resin and adsorption of resin decreased in proportion to the order of dielectric constant of solvents.

• 월간산업보건
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• s.105
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• pp.16-25
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• 1997

직업성 피부질환은 1988년 미국 전체 직업성 질환중 20%에 해당된다(미 노동부 자료 참고). 그 비율은 주에 따라 크게 달라지기도 한다. 피부질환은 어떤 주에서는 보상되는 직업성 질환의 대다수를 차지하기도 한다; 예를 들어, 캘리포니아와 플로리다주에서는 농작물에 의한 접촉성 피부염이 흔하다. 접촉성 피부염은 직업성 피부질환으로 보고되는 가장 흔한 피부질환이다. 이러한 사례의 4/5는 유기용제, 절삭유, 세척유, 알칼리, 산 등과 같은 자극성 화학물질에 대한 노출과 관련이 있다. 자외선은 어떤 화학물질(예를 들면, 코울 타르, 크레오소오트)과 반응하여, 이 화학물질 및 빛에 노출되는 부위에 자극성 접촉성 피부질환을 유발하기도 한다. 1/5의 사례는 에폭시 수지, 크롬, 식물 수지, 그 밖의 많은 것 등 특수 접촉 감광제와 관련될 수 있다. 강한 자극제에 노출되어 발상하는 화학적 화상은 비교적 흔하게 일어난다. 백반과 유사한 피부탈색은 드물게 일어나며 피부 접촉을 통하여 야기하는 특수 화학물질과 관련될 수 있다. 여드름과 모낭염은 기름 및 유지들과의 피부 접촉을 통하여 생겨날 수 있다. 10대 여드름과 구별되는 염소성 여드름이라고 불리는 질환은 여러 종류의 염화 탄화수소들(예를들면 다브롬화 디페닐, 다염화 디페닐, 디옥신)에 노출되어 발생되기도 한다. 신체적인 손상으로 반복되는 외상부위에 가골이 형성되기도 한다. 여러 종류의 일에 특징적인 것(예를 들면 바이올린 연주자의 목에 가골)이 소위 "직업적인 표지" 이다. 전기톱 작동 기술자, 분쇄기 작동기술자, 지하 광산 암석 천공 기술자에게서 발생하는, 손 - 팔 부위의 진동은 오랜기간 혹은 심하게 노출된 노동자에 있어서 - 손에 혈관수축질환 - 진동장애 백색 수지질환을 일으킬 수 있다. 피부암은 직업과 관련이 있다고 할 수 있다. 하지만 몇몇 사례가 산재 관련 기관에 보고외어 있지만, 암등록소에 보고는 불완전하며, 피부암으로 인한 사망은 드물기 때문에 피부암의 발생률은 알 수 없다. 예방적인 방법은 개인보호구(장갑, 구두 등), 기계공학적 통제, 노동자 교육, 피부에 노출되는 것을 피하기 위해 주어진 일을 맡는 노동자들의 교대와 같은 관리적인 통제가 있다. 이러한 방법들은 화학적 화상, 알러지성 접촉성 피부염과 같은 피부염, 진동장애, 직업관련성 질환(예를 들면, 건선, 단순태선, 백반)을 예방하는데 도움이 된다. 만성 자극성 접촉성 피부염은 아직 잘 이해하고 있지 못하여 현재 예방하는 방법은 아직 만족스럽지 못하다.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.6
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• pp.436-441
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• 2013

An experiment using a 5 m-long sand column was performed to evaluate the resisting capability against micro-pollutants of the infiltration gallery, multi-purpose filtration pond and riverbank/bed filtration, of which the filtration distance is becoming increasingly shorter in Korea. Results suggested that the Korean riverbed sand contained significant amount of organics, resulting in a relatively vigorous adsorption of chloride ion on the sand surface. Results also indicated that while phenol was not detected in the column filtrate, both 1,4-dioxane and diazinon were exposed to adsorption by the sand as they moved through the column, decreasing their peak concentrations during the movement. It can be expected that the peak concentrations will diminish significantly in the practical scale due to its longer travel distance.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.161-171
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• 1997

Anodic regeneration of PCB enchant and cathodic deposition of copper using electrochemical method has been studied. Cu(I)/Cu(II) concentration ratio as a function of Cu(I) oxidation at the anode was measured from the potential difference between platinum and Ag/AgCl/4M KCl electrodes. Chlorine gas evolution was minimized by maintaining Cu(I) concentration above a specific concentration and using non-porous graphite electrode. Dendritic copper deposition was observed at the cathode and the optimum conditions for Cu deposition was identified as the current density of $360mA/cm^2$, and copper concentration of 12 g/l. Titanium was the most effective cathode material which showed a higher current efficiency and copper recovery. The current efficiency decreased with increasing temperature, but the highest power efficiency was achieved at $50^{\circ}C$.

• Applied Chemistry for Engineering
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• v.20 no.2
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• pp.165-171
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• 2009

Resins were synthesized by mixing 1-aza-15-crown-5 macrocyclic ligand attached to styrene (2th petroleum in 4th class hazardous materials) and divinylbenzene (DVB) copolymer with crosslinkage of 1%, 2%, 8%, and 16% by substitution reaction. The characteristic of these resins was confirmed by content of chlorine, element analysis, thermogravimetric analysis (TGA), surface area (BET), and IR-spectroscopy. The effects of pH, time, dielectric constant of solvent and crosslinkage on adsorption of metal ion by the synthetic resin adsorbent were investigated. The metal ion showed a fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in an increasing order of uranium $(UO_2^{2+})$ > lead $(Pb^{2+})$ > chromium $(Cr^{3+})$ ion. The adsorption was in the order of 1%, 2%, 8%, and 16% crosslinkage resin and adsorption of resin decreased in proportion to the order of dielectric constant of solvents.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.304-309
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• 2008

Cryptand series ion exchange resins were synthesized with 1-aza-12-crown-4 macrocyclic ligand attached to styrene (4 series dangerous matter) divinylbenzene (DVB) copolymer with crosslink of 1％, 2％, 4％ and 8％ by a substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, electron micrograph, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of uranium (${UO_2}^{2+}$) ion were investigated. The uranium ion showed a fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium (${UO_2}^{2+}$) > nickel ($Ni^{2+}$) > gadolinium ($Gd^{3+}$) ion. The adsorption was in order of 1％, 2％, 4％, and 8％ crosslinked resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.

• Journal of the Korean Electrochemical Society
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• v.24 no.3
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• pp.35-41
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• 2021

In this study, the effect of zwitterionic surfactant on Cu electrodeposition was investigated through cyclic voltammetry. With the addition of (dodecyldimethylammonio)propanesulfonate (DDAPS) as a representative zwitterionic surfactant in the electrolyte for Cu electrodeposition, the electrochemical Cu²⁺ reduction was inhibited on Cu and glassy carbon electrodes. Its inhibition effect was similar to that of cationic surfactant rather than anionic surfactant. Moreover, DDAPS interacted with chloride ion and exhibited the mass transfer-dependent inhibition behavior, which indicates that its inhibition function is associated with the formation of its surface aggregates on anion-covered Cu surface. In addition, adsorbed DDAPS slightly reduced the surface roughness of Cu electrodeposits. These characteristics were similar to those of cationic surfactant, but less obvious. It means the effect of DDAPS on Cu electrodeposition originates from the cationic head group which is shield by anionic head group.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.6
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• pp.677-686
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• 2006

This study was the effectiveness of two downflow BAF(Biological Aerated Filter) systems at conventional water treatment system. A BAF reactor placed in front of coagulation and sedimentation tanks(Mode A) and after coagulation and sedimentation tanks(Mode B) that were compared in terms of removal of suspended particles, organic matters, and ammonia nitrogen. The suspended particles removal efficiency was over 80% for both Mode A and B, although Mode A gave slightly better results. $BOD_5$ removal and nitrification efficiencies were more than 90% for both reactor. The organic matter and ammonia removals were also superior in the Mode A. The biofilm thickness and biomass increased as increment of EBCT and the upper part of reactor more about 30% than lower part. The specific oxygen uptake rate(SOUR) was higher the upper part of reactor and Mode A than the lower part of reactor and Mode B. A cost analysis showed that the Mode A system was more cost effectiveness. It could save the coagulant dose by about 67% and the chlorine demand by about 95%. The ideal place to put the BAF reactor was in front of the coagulation/sedimentation process.

• Journal of the Korean Chemical Society
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• v.24 no.2
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• pp.139-145
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• 1980

High spin iron(II) complexes of 1,4,8,11-tetraazacyclotetradecane (cyclam), a macrocyclic ligand, and 1,5,8,12-tetraazadodecane (3,2,3-tet), a noncyclic ligand, have been prepared. The reaction of low spin $[Fe(cyclam)(CH_3CN)_2](ClO_4)_2$ with chloride ion in methanol produces high-spin $[Fe(cyclam)Cl]ClO_4$. Although $[Fe(cyclam)(CH_3CN)_2](ClO_4)_2$ is low spin, $[Fe(3,2,3-tet)(CH_3CN)_2](ClO_4)_2$ isolated in the present study is high spin. This difference is explained in terms of the smaller constrictive effect exerted by the noncyclic ligand than the cyclic ligand. The isolation of $[Fe(cyclam)Cl]ClO_4$ provides evidences against the current view that the presence of either unsaturation or substituents on the macrocyclic ligands is necessary for the successful preparation of high spin five-coordinate iron (II) complexes. Reactions of $[Fe(cyclam)Cl]ClO_4\;and\;[Fe(3,2,3-tet)(CH_3CN)_2](ClO_4)_2$ with carbon monoxide yield low spin six-coordinate $[Fe(cyclam)Cl(CO)]ClO_4\;and\;[Fe(3.2,3-tet)(CH_3CN)(CO)](ClO_4)_2$, respectively.

• Journal of the Korean Geotechnical Society
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• v.23 no.12
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• pp.25-32
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• 2007

This study is to evaluate the effect of chemical attack on durability and deterioration of lining concrete in tunnel. Surface examination, nondestructive inspection, uniaxial compressive strength test, carbonation test, chloride diffusion test, micro-structural analysis were performed to analyze the deterioration of lining concrete in tunnel constructed 70 years ago. From surface examination results, the tunnel had been repaired and reinforced in several times. It has many cracks, water-leakage, efflorescence and exploitation. Compressive strengths obtained from nondestructive inspection and uniaxial compressive strength test have measured $17.5{\sim}34.7MPa$, and $12.8{\sim}40.3MPa$, respectively. Carbonation depth specimen cored from concrete lining has ranged from 3mm to 27mm. From chloride diffusion test, most specimens have low permeability. And the XRD analysis was able to detect ettringite and thaumasite, which were confirmed by SEM and EDS results to be the causes for the deterioration of lining concrete.