• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.225-228
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• 2005

This paper was accomplished for analyzing the reason of the above deterioration happened on the deck of concrete bridge. The bridge was constructed at 660m above the sea level having more freezing and snowing days. Therefore, it is placed on the particular condition sprinkling $CaCl_2$ enough for keeping up with moderate traffic condition. When it is considered to the former condition, the bridge can be assumed to potentialities for combined deterioration with freezing-thawing under sprinkling deicing chemical. Core specimens were gathered from the concrete deck for clearing the reason of the above deterioration exactly, and it is used for various tests for measuring the compressive strength, elastic modulus, content of $Cl^-$, freezing-thawing at the fresh and salt water. As a result of freezing-thawing test, the specimen at the fresh water has over 90$\%$ of durability factor, but another specimen at 1$\%$ of salt water has 0$\%$ of durability factor at 140 cycles of the freezing-thawing. The result means that frost damage is sccelerated at the salt water. Therefore, the deterioration of the concrete deck is estimated to be occured by combined effects of freezing-thawing and chloride ion attack.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1998.12a
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• pp.49-65
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• 1998

전자문서, 전자결재, 행정 EDI 등과 같은 전자적 매체를 이용한 행정정보화를 실현하기 위한 전자정부 구축 노력이 추진됨에 따라 전자정부 환경에서 발생할 수 있는 각종 정보보호 요소들을 원천적으로 해결하기 위해 전자서명 등과 같은 공개키 기반의 암호 기술 적용이 필수적 요소로 여겨지고 있으나, 공개키 암호기술에 사용되는 암호화 키의 체계적인 관리를 위한 공개키 인증 체계(PKI) 구축에 대한 방안마련이 미흡한 실정이다 이에 본 논문에서는 전자정부 환경에서 공개키 기반 암호 기술의 효과적인 적용을 위한 공개키 인증 체계 모델과 관련 조직 체계 구성 방안에 대해 제안하고자 한다.

• Journal of Environmental Science International
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• v.14 no.10
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• pp.905-910
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• 2005

The purpose of this study is the comparative analysis of Susan citizens' images of Eulsook-do as a coastal tourism destination before and after the construction of a road bridge across the Nakdong estuary in order to analyze local people's changes in leisure patterns. Analysis of the images of a pre-construction Eulsook-do that people aged both 40 and less and 50 and more had on five dimensions showed values higher than zero(0) that suggests neutral image, while their images of a post-construction Eulsook-do showed the shrinking size of pentagon on all five dimensions: ET(Entertainment), CA(Culture & Art), EE(Environment & Ecology), RC(Recreation) and LP(Leports) dimensions. Its pre- and post- construction image analysis conducted 20 years after it came to be built finds that the road bridge construction has led to the ecological, environmental disruption of the coast and the lower Nakdong river, having negative influence on the images of Eulsook-so.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.11
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• pp.809-814
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• 2013

In this study, physical properties and heavy metal contents of sediments obtained from the bottom of Gwangan bridge were measured to determine pollution level of the sediments. From the results of the oxide contents of the sediments, $SiO_2$ was decreased as the sampling points became more distant from the stream of river. On the contrary, CaO showed opposition aspect to $SiO_2$. Ignition loss of sediments ranged from 7.2 and 14.3% and 0.9 and 5.5% for TOC. For EPA guidelines of ignition loss, all sampling points were classified as heavily polluted areas. When TOC was considered, all areas were classified as lowest effect level except for GW7 where classified as no effect level. All areas were free of heavy metal contamination evaluated by USEPA and Canadian guidelines. However, all areas were classified as heavily contaminated areas due to the high value of ignition loss when USEPA was used.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.108-111
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• 2002

For the global microwave market, high RF power or deluxe model is applying for Inverter gradually. In this study, 120V/1200W high power Inverter was proposed and verified by an optimized design of PFM-type. Especially the steady power output control was fulfilling at +/- $10\%$ input voltage variation.

• Journal of the Speleological Society of Korea
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• no.89
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• pp.46-58
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• 2008

동굴 퇴적물의 형성과정은 1단계 기권 (Atmosphere): 빗방울 (H2O) 이 대기중에서 CO2의 혼합으로 산성비 (H2CO2)가 되어 석회암 (CaCO3)에 떨어져서 최초의 용식작용이 시작된다. 2단계 토양권 (Pedosphere): 산성비와 석회암성분이 합쳐 형성된 가용성 화합물 (Ca(HCO3)2)은 식생부식(植生腐植)에 의한 토양 (Humic acidic soils) 에 의해 기반암의 용식이 촉진 되어 지표에는 Karren과 석문 (석문(石門) Natural Bridge), 와지 (Dolines, Sinkholes) 지형을 형성시키고, 암석의 분순물은 지표에 남겨져서 결국 적색풍화토 (Residuum, Risidual Redish Soils) 를 만든다. 3단계 암권 (Lithosphere): 용식작용에 의해 지상에서 지하 로 확대되어진 모암의 균열을 타고, 지하의 공간이 지하수의 유입과 유출에 의해 점차 확대되어 동공형의 Conduites; Voids; Shaft 이라는 특수지형을 형성시키고,동굴의 천정으로부터 나온 Ca(HCO3)2 는 탄산염의 지속적인 분해 공급에 의해 동굴내에는 종류석, 석순, 유착석 (Speleothem)등의 새로운 동굴지형 (Speleoscape)을 조성하게 된다. 4단계 수권 (Hydrosphere): 동굴의 형성작용을 거친 물은 동굴지하수로 잔여 Calcite를 함유한 채로 유출 (Spring) 된다. 동굴을 떠난 잔여 Calcite는 또다시 하천유역에 침전시켜서 석회화 단구형의 집적지형 (Tufa Formation: Tufa Dam, Tufa Flowstone)을 최종적으로 동굴을 나와 외벽 이나 하천의 바닦에 형성하는 과정을 거치면서 카르스트 지형의 발달과정이 1차적인 순환을 마치게 된다.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.123-131
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• 1982

The purpose of this study was to observe the responses of the remaining pulp tissue after pulpotomy upon the several kinds of $Ca(OH)_2$ products and the responses of periapical tissue upon some root canal filling materials after extirpation. For pulpotomy, the class V cavities were prepared on the premolars, molars and upper canines, and the pulp was amputated. Each drug was placed over the amputated tissue and cavity was sealed with zinc oxide eugenol cement. The drugs which were used for the study were Dycal (Caulk Co. U.S.A.), Cavitec (Kerr Co. U.S.A.), Calvital, Nobudyne and Neodyne (Neo Dental Chemical Products). For extirpation, the endodontic cavities were prepared on the lingual surfaces of anterior teeth, and the pulp tissues were extirpated as routine method. After enlarging, irrigation, and measuring of root length by taking X-ray, each root canal filling material was filled in the canal with gutta percha cone, and endodontic cavity was sealed with zinc oxide eugenol cement. Zinc oxide eugenol, $Ca(OH)_2$ (Eli Lilly Co. U.S.A.) and Vitapex (Neo Dental Chemical Products) were used as root canal filling materials. Animals were sacrificed after 1, 3 and 6 weeks following the operation. The teeth were decalcified in formic acid, sectioned and stained with hematoxylin eosin. Microscopic examination revealed as follows. 1. Dycal: The dentin bridge formation was observed at the 3rd week after pulpotomy. Inflammatory conditions which were infiltration of inflammatory cells and dilatation of blood vessels were kept in remaining pulp tissue at the 6th week. 2. Calvital: The dentin bridge was observed at the 1st week after pulpotomy. As the time clasped, the pulp tended to be the fibrous degeneration. 3. Cavitec, Nobudyne and Neodyne: In the case of Cavitec and Nobudyne, the incompleted and irregular dentin bridge was observed at the 6th week, and in Neodyne, was observed at the 3rd week. The severe inflammatory changes were seen in the remaining pulp tissue. As the time clasped, the fibrous degeneration tended to spread in the remaining pulp tissue. 4. $Ca(OH)_2$: Osteocementum was formed at the 3rd week, the matrix of cementum and dentin were resorted, and infiltration of lymphocytes was seen in periapical tissue when $Ca(OH)_2$ was used as canal-filling materials. S. ZOE and Vitapex The cementum like substance was seen in periapical portion at the 1st week, when ZOE and Vitapex were used as root canal filling materials. As the time elapsed, the matrix of cementum and dentin tended to be resorted. At the 6th week, the inflammatory condition of periapical tissue was continued in the case of ZOE, but was reduced in the case of Vitapex.

• Restorative Dentistry and Endodontics
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• v.14 no.1
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• pp.109-118
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• 1989

The purpose of this study was to investigate the bio-stimulating effect of low power density laser radiation on the mechanically exposed pulp. Class V cavities on dog's teeth were prepared and the pulps were mechanically exposed with a round bur. In control group, the exposed pulps were capped with $Ca(OH)_2$ powder and the cavities were sealed with Z.O.E.. In experimental group A, the pulps were irradiated with GaA1As laser for 5 minutes and then they were treated the same as control group. In experimental group B, the exposed pulps were covered by aluminum foil and sealed with Z.O.E. after they were irradiated with the laser as the experimental group A. In the all groups, the pulps were histopathologically observed at the time intervals of 1, 2 and 3 week after experiment and the results were statistically evaluated. The results were as follows: 1) In control and experimental groups, mild vascular congestion and bleeding was found in most of the specimens and for the new formation of dentin bridge, experimental group A had the most cases. The dentin bridge had discontinuous osteodentin like appearance without any dentinal tubules. Inflammatory cell infiltration consisted of acute and chronic inflammatory cell, and the formation of microabscess was also observed. 2) The degree of inflammatory cell infiltration was not significantly different among control group and experimental groups at 1 week, 2 week and 3 week. 3) The formation of new dentin bridge was not significantly different between control group and experimental group A at 1 week, but at 2 week and 3 week, experimental group A showed significantly more cases of new dentin formation than control groups. (P < 0.05). 4) Between control group and experimental group B, there was no significant difference in formation of the new dentin bridge at 1, 2 and 3 week. (P> 0.05). 5) There was no significant difference in formation of the new dentin bridge at 1 and 2 week between experimental group A and experimental group B, but at 3 week, the former significantly had more cases of new dentin bridge formation than the latter.(P < 0.05).

• Restorative Dentistry and Endodontics
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• v.24 no.4
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• pp.554-559
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• 1999

Aucubin, an iridoid glucoside isolated from Aucuba japonica, has pharmacological effects such as antimicrobial effect, liver protective function and inhibition of liver RNA and protein biosynthesis, etc. This study was performed to observe the effect of aucubin on the pulp tissue after pulpotomy. Aucubin was converted to aucubinogenin as an active form by ${\beta}$-glucosidase. In 3 Mongrel dogs, the pulps were mechanically exposed with a sterile round bur and excised with sterile excavator. After bleeding control, aucubin was applied on remaining pulp tissues and then they were sealed with IRM in experimental group. In control group, $Ca(OH)_2$ powder was applied on remaining pulp tissues and then they were sealed with IRM. After interval of 1 and 12 weeks, the dogs were sacrificed. The teeth were prepared for histologic evaluation and examined by light microscope. Aucubin 1 week group showed that mild inflammation and vascular congestion in most of the specimen. More various degree of inflammation was found in experimental group than in control group. Premature calcified mass were found in the both 1 weeks groups. Continuous well-formed dentin bridge was found in both 12 weeks groups. Collectively, this study suggests that the possibility of aucubin as a medicament after pulpotomy.

• Journal of Microbiology and Biotechnology
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• v.23 no.1
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• pp.7-14
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• 2013

In the Bacillus amyloliquefaciens ${\alpha}$-amylase (BAA), the loop (residues 176-185; region I) that is the part of the calcium-binding site (CaI, II) has two more amino acid residues than the ${\alpha}$-amylase from Bacillus licheniformis (BLA). Arg176 in this region makes an ionic interaction with Glu126 from region II (residues 118-130), but this interaction is lost in BLA owing to substitution of R176Q and E126V. The goal of the present work was to quantitatively estimate the effect of ionic interaction on the overall stability of the enzyme. To clarify the functional and structural significance of the corresponding salt bridge, Glu126 was deleted (${\Delta}$E126) and converted to Val (E126V), Asp (E126D), and Lys (E126K) by site-directed mutagenesis. Kinetic constants, thermodynamic parameters, and structural changes were examined for the wild-type and mutated forms using UV-visible, atomic absoption, and fluorescence emission spectroscopy. Wild-type exhibited higher $k_{cat}$ and $K_m$ but lower catalytic efficiency than the mutant enzymes. A decreased thermostability and an increased flexibility were also found in all of the mutant enzymes when compared with the wild-type. Additionally, the calcium content of the wild-type was more than ${\Delta}E126$. Thus, it may be suggested that ionic interaction could decrease the mobility of the discussed region, prevent the diffusion of cations, and improve the thermostability of the whole enzyme. Based on these observations, the contribution of loop destabilization may be compensated by the formation of a salt bridge that has been used as an evolutionary mechanism or structural adaptation by the mesophilic enzyme.