• Journal of Korean Society for Atmospheric Environment
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• v.17 no.1
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• pp.57-66
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• 2001

Gas phase photocatalytic oxidation of tetrachloroethylene (PCE) under 370 nm ultra-violet irradiation was investigated with TiO$_2$ catalyst. During the photocatalytic oxidation of PCE vapor several kinds of intermediate were produced, and the reaction pathways were proposed on the basis of the production sequency of the intermediates. The intermediates in the pathways of PCE oxidation were hexachloroethane, pentachlotoethane, 1, 1, 2-trichloroethane, carbon tetrachl-oride, dichloroacetylchloride, chloroform, 1,1-dichloroethane, phosgene, CO, $CO_2$, HCl, Cl$_2$.

• Journal of Environmental Science International
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• v.13 no.10
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• pp.903-909
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• 2004

A new method based on solid phase microextraction(SPME), coupled with GC/FID, has been developed for the determination of PCE and TCE in water samples. The experimental parameters affecting the SPME process (i.e, kinds of fibers, extraction time, desorption time, extraction temperature, volume ratio of sample to headspace, salt addition, and magnetic stirring) were optimized. The coefficients of determination ($R^2$) for PCE and TCE were 0.9951 and 0.9831, respectively when analytes concentration ranges from 10 to 300$\mu$g/L. The relative standard deviations were 3.4 and $2.1\%$ for concentration of 10$\mu$g/L(n=5), respectively. The detection limits of PCE and TCE were 0.5 and l.3$\mu$g/L, respectively.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.224-239
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• 1994

In this study we examined several subjective symptoms in an exposed group and an unexposed group to perchloroethylene. The exposed group consists to 30 workers employed in 23 dry-cleaning establishments located in Chung Cheung Do, whereas the unexposed group consists of 42 officers employed in a certain university. This study was conducted from October, 1993 to March, 1994. Also we investigated personal exposure levels and area concentration of PCE, and performed hematological and biochemical examination in blood and urine samples from the exposed group. The results are : 1. The exposed group highly complains several subjective symptoms, particularly in neuropsychiatry, eye, respiratory system and digestive system, compared with the unexposed group. But complaint rates in the exposed group are not related with PCE exposure levels. 2. PCE exposure levels for all dry-cleaning establishment varied widely, from 0.18 to 37.58ppm. The mean exposure level for centers of chain was 16.85ppm, and for local laundries was 8.83ppm, while for self-service establishment it was 3.07ppm. Eighty three percent of the workers were exposed less than the half-level(25.0ppm) of the Korea 50.0ppm standard for eight-hour PCE exposure. Seventeen percent of them exceeded the half-level of the Korea TLV. 3. Statistical correlation exists between the work load(number of operation cycles of equipment and the mass of processed textiles) and the personal exposure levels to be observed. 4. In hematological examination the values of WBC, RBC, Hgb, Hct, MCV, MCH, MCHC and PLT in the exposed group were within normal ranges. In biochemical examination(GOT, GPT, ALP, U-A and LDH) most of the items were within normal ranges. From this surveys conducted on 23 dry-cleaning establishments, the complaint rates of the exposed group to PCE in several subjective symptoms were higher than those of the unexposed group, and PCE exposure levels in all dry-cleaning establishment were below the Koera standard 50.0ppm. In hematological and biochemical examination the significant abnormalities by occupational exposure to PCE were not observed. However, the workers employed in dry-cleaning establishments are always faced with risk, becauses they are also exposed to several organic solvents used to remove stains. Therefore, various measures to improve occupational environment in dry-cleaning establishment should be considered.

• Journal of Wetlands Research
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• v.12 no.1
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• pp.23-31
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• 2010

Chlorinated aliphatic hydrocarbons (CAHs) such as tetrachloroethylene (PCE), 1,1,1-trichloroethane (1,1,1-TCA) are the contaminants most frequently found in soil and groundwater. They have a potential to be toxic to and persistent in environment. This study is focused on selection of zero-valent metal and ores for the removal of high concentration PCE or 1,1,1-TCA and mixture of two compound. For the screening of suitable metals, we measured dechlorination rate, removal capacities and economics by using batch reactor test. This results suggest that removal rate and dechlorination of high quality iron and zinc are higher than slag and nature ores like zinc and manganese. Among nature ores, zinc ores(64% purity) have highest removal capacities. And in economics zinc ores is 10 times better than high quality metal tested. We conclude zinc ore is most suitable metal for the removal of PCE or 1,1,1-TCA.

• Advances in environmental research
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• v.3 no.2
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• pp.151-162
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• 2014

Among the combination of 4 different second metals and 3 different noble metals, Ni 10%-Pd 1%/hematite (Ni(10)-Pd(1)/H) showed best tetrachloroethylene (PCE) removal (75.8%) and production of non-toxic products (39.8%) in closed batch reactors under an anaerobic condition. The effect of environmental factors (pH, contents of Ni and Pd in catalyst, and hydrogen gas concentration) on the reductive dechlorination of PCE by Pd-Ni/hematite catalysts was investigated. PCE was degraded less at the condition of Ni(5)/H (13.7%) than at the same condition with Ni(10)/H (20.6%). Removals of PCE were rarely influenced by the experimental condition of different Pd amounts (Pd(1)/H and Pd(3)/H). Acidic to neutral pH conditions were favorable to the degradation of PCE, compared to the alkaline condition (pH 10). Increasing Ni contents from 1 to 10% increased the PCE removal to 89.8% in 6 hr. However, the removal decreased to 74.2% at Ni content of 20%. Meanwhile, increasing Pd contents to 6% showed no difference in PCE removal at Pd content of more than 1%. Increasing H2 concentration increased the removal of PCE until 4% H2 which was maximumly applied in this study. Chlorinated products such as trichloroethylene, 1,1-dichloroethylene, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, and vinyl chloride were not observed while PCE was transformed to acetylene (24%), ethylene (5%), and ethane (11%) by Ni(10)-Pd(1)/H catalyst in 6hr.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.68-71
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• 2004

Effects of surfactants and natural organic matter (NOM) on the sorption and reduction of tetrachloroethylene (PCE) and chromate with iron were examined in this study. PCE and chromate reduction by iron depended on the ionic type of the surfactants in this study. The apparent reaction rate constants of PCE with Triton X-100 and hexadecyltrimethyl ammonium (HDTMA) at one half and two times of the critical micelle concentration (CMC) were relatively higher than without surfactants because of the enhanced PCE partitioning and surface concentration. In the presence of sodium dodecyl benzene sulfonate (SDDBS) at 2000 mg/L and NOM at 50 mg/L, the apparent reaction rate constants of PCE increased, but TCE production decreased. The enhanced removal rate of PCE was not due to the dechlorination, and the sorption was dominant iron with SDDBS and NOM. The apparent reaction rate constants of chromate by iron with Triton X-100 and NOM were 1.4-3.1 times lower than without surfactants while that with HDTMA was two times higher than without HDTMA, When the sorbed HDTMA molecules form admicelles, negatively-charged chromate has an affinity for the positively-charged HDTMA head group.

• Convergence Security Journal
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• v.13 no.6
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• pp.3-9
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• 2013

With the rapidly changing information communication environment and development of technologies, the informati on networks are evolved from traditional fixed form to an active variable network that flexible large variety of data can be transferred. To reflect the needs of users, the next generation using DWDM (Dense Wavelength Division M ultiplexing) transmission system and OXC (Optical Cross Connect) form a dynamic network. After that GMPLS (Ge neralized Multi-Protocol Label Switching) can be introduced to dynamically manage and control the Reconfigurable Optical Add-drop Multiplexer (ROADM)/Photonic Cross Connect (PXC) based network. This paper propose a softw are architecture of Path Computation Element (PCE) protocol that has proposed by Internet Engineering Task Force (IETF) to path computation. The functional blocks and Application Programming Interface (API) of the PCE protoco l implementation are also presented.

• Journal of Environmental Health Sciences
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• v.26 no.2
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• pp.6-13
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• 2000

PCE(tetrachloroethylene) 분해능을 보유한 그람 양성, 내생포자 형성의 혐기성균이 일본 기후현의 한 전자제품공장으로부터 분리되었다. 이 균은 생화학적 특성 및 16S rRNA 분석결과에 의하여 C. bifermentans인 것을 거쳐 cDCE(cis-1,2-dichloroethylene)로 전환되었다. 전자공여체로서 효모엑기스는 PCE 분해에 있어 가장 효과적이었으며 효모엑기스를 공급한 조건에서의 PCE 탈염소화 속도는 0.41 $\mu$mol/h.mg protein 이었다. 한편 본 균주는 PCE 뿐만 아니라 각종 유기염소화합물에 대해서도 분해능을 보유하고 있는 신종의 PCE 분해균으로서 각종 유기염소화합물에 오염된 지하수 및 토양에서의 In situ bioremediation 적용에 있어 유용할 것으로 기대된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.12
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• pp.1195-1210
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• 2012

In this paper, we propose a new signaling protocol as an extension of Generalized Multi-Protocol Label Switching (GMPLS) based PCE protocol for control carrier ethernet. The proposed protocol is not only compatible with the GMPLS PCE standard protocol, but also provides the topology discovery and configuration. In order to verify interoperability, we implement the proposed protocol as well as the system integrating functions including commercial system for testbed. In addition, we have simulated topology discovery test for proposed protocol performance.

• Journal of Soil and Groundwater Environment
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• v.10 no.2
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• pp.52-58
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• 2005

In Korea, little attention has been paid to microbial perchloroethylene (PCE) and/or trichloroethylene (TCE) dechlorination activity and identification of microorganisms involved in PCE reductive dechlorination at a PCE-contaminated aquifer. We performed microcosm tests using the groundwater samples from 4 different contaminated sites (i.e. Changwon A, Changwon B, Bucheon and Yangsan) to assess PCE reductive dechlorination activity. We also adapted molecular techniques to screen what types of known reductive dechlorinators are present at the PCE-contaminated aquifers. In the Changwon A and Changwon B active microcosms where potential electron donors such as sodium propionate, sodium lactate, sodium butyrate, and sodium fumarate, were added, ethylene, an end-product of complete reductive dechlorination of PCE, was detected after a period of 90 days of incubation. In the Bucheon and Yangsan active microcosms, cis-1,2-dichloroethylene (c-DCE) was accumulated without the production of vinyl chloride (VC) and ethylene. Molecular techniques were used to evaluate the microbial community structures in the Changwon B and Yangsan aquifer. We found two sequence types that were closely related to a known PCE to ethylene dechlorinator, named uncultured bacterium clone DCE47, in the Changwon B site clone library. However, in the Yangsan site clone library, no sequence type was closely related to known PCE dechlorinators reported. It is plausible that microorganisms being capable of completely dechlorinating PCE to ethylene may be present in the Changwon B site aquifer. In this study we find that complete PCE reductive dechlorinators are present at some PCE-contaminated sites in Korea. In an engineering point of view this information makes it feasible to apply a biological reductive dechlorination process for remediating PCE- and/or TCE-contaminated aquifers in Korea.