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RISS 인기검색어
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- 저자 : 鄭賢株(Hyun-Ju Chung) (검색결과 201 건)
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정현주,양창섭,정우진,Chung, Hyun-Ju,Yang, Chang-Seob,Jung, Woo-Jin 한국군사과학기술학회 2015 한국군사과학기술학회지 Vol.18 No.3
This paper describes design and construction results of the measurement system developed on the purpose of measuring properties of AC magnetic field sensors used in the weapon system. The system for measuring the properties of AC magnetic field sensors consist of 3-axis helmholtz coil, signal generator, signal amplifier, sensor data acquisition unit and AC magnetic field sensor property measurement & analysis equipment including the operating software. By using this system, we can measure various properties of AC magnetic field sensor such as sensitivity, linearity and dynamic response in the frequency from 1 Hz to 10 kHz. Finally we also verified its performance by measuring the property of a MAG 639, standard magnetic field sensor of bartington instruments, with the developed measurement system.
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선체 부식 및 부식 방지장치에 의한 수중 전기장 신호 해석 방안 연구
정현주,양창섭,전재진,Chung, Hyun-Ju,Yang, Chang-Seob,Jeon, Jae-Jin 한국군사과학기술학회 2008 한국군사과학기술학회지 Vol.11 No.2
The galvanic corrosion of a vessel, or systems fitted to minimize the ship's corrosion such as ICCP (Impressed Current Cathodic Protection) system and sacrificial anodes, can lead to significant electrical current flow in the sea. The presence of vessel's current sources associated with corrosion will give rise to detectable electric field surrounding the vessel and can put it at risk from mine threats. For this reason, it is necessary to design corrosion protection systems so that they don't only prevent a hull corrosion but also minimize the electric field signature. In this paper, we describe theoretical backgrounds of underwater electric field signature due to corrosion and corrosion protection system on naval vessels and analysis results of the electric field according to the ship's hull and it's propeller coating damage and ICCP anode displacement.
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Inhibition of Plaque Formation on the Titanium Surface by Anti-bacterial Varnish
정현주,이상현,김영준,Chung, Hyun-Ju,Lee, Sang-Hyun,Kim, Yung-Jun,Williams, Ray C. The Korean Academy of Periodontoloy 2000 Journal of Periodontal & Implant Science Vol.30 No.4
매식된 인공치아의 성공을 위해서는 적절한 교합과 수동적 적합성을 갖는 보철물의 제작과 구강내 노출 직후부터의 세균성 치태조절이 요구된다. 본 연구는 전처리(passivation과 tridodecyl - methyl - ammonium chloride(TDMAC) 처리)가 다른 타이타늄 표 면에 chlorhexidine varnish와 테트라사이클린 을 도포시 약제의 방출역학을 알아보고 구강내 치태형성의 억제정도를 평가하기 위하여 시행 되었다. 이를 위해 방출용액으로 인산완충액 성분의 인조타액을 1일${\sim}$1개월간 매일 교환하여 약제농도를 측정하고 타이타늄 박막에 잔류한 약제 활성을 측정하였으며 항균제 도포한 타이타늄 원판을 부착한 장치를 구강내 위치시킨 1일${\sim}$3주 후 원판을 제거하여 주사전자현미경으로 세균 부착상을 관찰하였다. 테트라사이클린은 TDMAC 처리된 표면에서 $10{\sim}18$일까지 유효농도로 방출되었고 표면의 유효 항균 활성은 $3{\sim}4$주간 유지되었으며, chlorhexidine varnish 도포 시에는 TDMAC 전처리시 초기에 $3{\sim}7$일 간 증가한 유효 항균 활성을 방출하여 매식지대치 등에 이러한 항균제도포 시 매식치 주위환경에 항균활성 공급원으로 작용할 수 있음을 보였다. 주사현미경적 관찰시 모든 타이타늄 표면에서 구강내 위치 30분 후에는 세균이 부착되어 있지 않고 타액 단백질 성분에서 유래한 것으로 보이는 피막물질이 표면을 부분 또는 전면에 걸쳐 덮고 있었다. 구강내 노출 2시간 후 항균제 미도포 표본들에는 약간의 구균이 단층으로, $1{\sim}3$일 후에는 부분적으로 두꺼운 세균층을 형성하였고 7일 후에는 표면전체에 걸쳐 세균층이 덮여있었으며 주로 구균과 약간의 간균이 주종을 이루었다. 항균제 도포시 구강내 노출 1주일 이전까지는 미도포군에 비해 치태형성이 지연되는 경향을 보였지만 2주 이후에는 세균 수나 치태형성 양상이 유사하였다. 이 연구로부터 항균제 도포시 1주일 이전의 초기 치태형성을 감소시킬 수 있음을 알 수 있었으며 이러한 연구결과는 타이타늄 임프란트 지대치 표면에 항균제의 도포가 임상적으로 유용할 수 있음을 시사하였다.
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함정의 선체 부식에 의한 수중 전자기 신호 예측에 관한 연구
정현주,양창섭,주혜선,전재진,Chung, Hyun-Ju,Yang, Chang-Seob,Ju, Hae-Sun,Jeon, Jae-Jin 한국군사과학기술학회 2012 한국군사과학기술학회지 Vol.15 No.2
Corrosion currents flow through the seawater due to the different electrochemical potential between a hull and a propeller under the draft line of ship. Additionally, in order to protect the hull and other sensitive anodic parts of the ship from corrosion, the corrosion protection system, called impressed current cathodic protection(ICCP) equipment has been installed in most naval ships. Those currents could be harmful to the electromagnetic silencing of the naval ship because sea mines are triggered by even a feeble field value. In this paper, we described electric and corrosion related magnetic fields by ship's galvanic corrosion and a corrosion protection system, and prediction results of electric and corrosion related magnetic fields at any depth for the model ship.
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치주조직재생유도술용 비흡수성 차폐막 (e-PTFE membrane)에의 세균부착 및 침투
정현주,이성미,이호재,김옥수,Chung, Hyun-Ju,Lee, Sung-Mi,Lee, Ho-Jae,Kim, Ok-Soo 대한치주과학회 1996 Journal of Periodontal & Implant Science Vol.26 No.1
This study was performed to observe the bacterial adhesion and penetration to e-PTFE membrane following guided tissue regeneration(GTR) procedure and to evaluate the association of the membrane exposure and bacterial contamination with the clinical outcome. For the study, ten infrabony defects in 9 patient were treated by mucoperiosteal flap operation including placement of the e-PTFE membrane. The treated teeth were monitored weekly for the membrane exposure, gingival recession and gingival inflammation. The membranes were retrieved after 4 to 6 weeks, examined by SEM for bacterial contamination and adherent connective tisue elements, and observed under LM for the bacterial penetration into membrane. Three months postsurgery, the defect sites were clinically reexamined for the changes in attachment level and probing depth. Comparison of the ultrastuctural findings and clinical outcome revealed that extent of membrane exposure and bacterial contamination of the membrane was inversely associated with clinical attachment gain. From this finding, the extent of membrane exposure and the bacterial contamination on the apical portion of the e-PTFE membrane at the time of removal seemed to be a critical determinant on the clinical outcome of GTR and the membrane exposure needs to be controlled for optimal results.
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급속진행형치주염에서 치석제거술과 국소 약물송달제재의 병용효과
정현주,진유남,송우성,김영준,Chung, Hyun-Ju,Jin, Yu-Nam,Song, Woo-Sung,Kim, Young-Jun 대한치주과학회 1994 Journal of Periodontal & Implant Science Vol.24 No.3
Rapidly progressive periodontitis is known to be usually associated with systemic problems and improved with antibiotic therapy. Recent experiments in which bioresorbable polycaprolactone was polymerized with minocycline has shown that the system released effective antibiotic concentration during the 7 days' period. This clinical trial was to compare the efficacy of a minocycline film(poly-caprolactone+polyglycol+10% minocycline) insertion plus supragingival scaling(MS) or subgingival scaling & root planing(MSRP) with the scaling(S) or subgingival scaling & root planing alone(SRP), at improving the periodontal condition in RPP. Fifteen patients were examined for plaque accumulation, gingival inflammation, probing depth and attachment loss at baseline, then 1, 2, 4 and 8 weeks after 4 treatment regimens were randomly undergone in 4 comparable sites(PD>5mm, LA>3mm) in each subject. Results revealed statistically significant treatement effect with a reduction in a probing depth in SRP(2.0mm), MS(1.8mm), and MSRP(2.1mm). There was no significant reduction in the supragingival scaling alone group(0.6mm). Similarly, attachment levels were significantly improved in the SRP(1.5mm), MS(2.0mm) and MSRP(2.0mm) groups. Net % BOP reduction at 8 week compared to baseline was 6.7% (S), 26.7% (MS), 26.7% (SRP), and 33.3% (MSRP). MSRP produced the greatest improvement in BOP at 8 week. This data suggests that a subgingival minocycline delivery system as a adjunct to scaling alone or scaling & root planing may produce significant clinical benefits over scaling alone in rapidly progressive periodontitis patients.
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정현주,Chung, Hyun-Ju 대한치주과학회 1996 Journal of Periodontal & Implant Science Vol.26 No.1
There were many reports that elevations in the levels of active and latent collagenase in gingival crevicular fluid(GCF) have been correlated positively with periodontal disease activity. To provide a simple diagnostic approach for testing GCF collagenolytic activity, the detection limit of enzyme activity was compared using radiofibril assay(Sodek et.al.1981) and spectrophotometric collagenolytic assay(Nethery et al. 1986). The detection limits of both assay for standard bacterial enzyme were similar and the radiofibril assay showed a little (1/2) lower detection limit for tad pole collagenase. To evaluate the relationship between periodontal tissue destruction and the collagenolytic activity, GCF was collected, and latent and active enzyme activities were measured by a spectrophotometric collagenolytic assay. Twelve subjects showing progressive lesions were selected according to the presence of immediate tissue destruction, frequent abscess formation, and increasing need for tooth extraction, and the absence of underlying systemic disease and previous antibiotic medication history within 6 months. Comparisons were made between sites with either: 1) inflammation with a previous history of progressive loss of periodontal tissue and bone support(2l progressive sites): 2) previous history of bone loss and periodontal destruction but now clinically stable(12 comparably stable sites); or 3) no loss of periodontal tissue and bone support(11 control sites including 5 gingivitis sites and 6 healthy sites). Active collagenase activity was the highest in the progressive sites and decreased in the order of the gingivitis sites, the stable sites, and the healthy sites. The total enzyme activity was $2{\sim}3$ fold higher in the progressive sites and the gingivitis sites, compared to the stable and the healthy sites. The ratio of active to total collagenolytic activity was twice in the progressive sites. Analysis of active collagenase level(5mU) and the ratio of active to total collagenolytic activity(0.8) as a diagnositic test indicates that these measurements have the sensitivity of 0.81 and 0.86, the specificity of 0.70 and 0.65, and the overall agreement of 0.75 and 0.73, respectively. Thus, this method has significant merits as a diagnostic tool to determine wherher the site is in a state of remission or progression.
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