• 한국가스학회지
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• 제16권4호
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• pp.52-58
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• 2012

최근 대기환경규제의 강화로 화학공장에서 발생하는 폐가스를 소각 처리하는 경우가 증대되고 있다. 이러한 소각설비는 저장탱크 상부와 배관을 통해 연결되어 화염을 통하여 폐가스를 연소 소각시키기 때문에, 배관을 따라 화염이 역화될 경우에는 치명적인 사고로 연결될 수 있다. 본 연구는 아크릴산 제조공정의 소각시스템에서 발생한 중대산업사고에 대해 폭발의 3요소와 화염의 전파 원인을 분석하여 사고 예방대책 및 안전성 향상 방안을 다음과 같이 제시하였다. 첫째, 소각시스템의 송풍기를 재 가동하기 전에는 공기 또는 불활성 가스로 충분히 희석하여 폭발을 예방하여야 한다. 둘째, 폭굉으로 전이된 화염이 저장탱크로 전파되지 않도록 소각설비의 전단 및 저장탱크 상부에 폭굉용 화염방지기를 설치하는 것이 필요하다. 섯째, 폭연용 화염방지기를 그대로 사용할 경우에는 그 전단에 파열판을 설치하거나 저장탱크 상부와 소각설비의 배관을 후드식으로 연결하여 폭굉으로 전이된 화염을 저장탱크 밖으로 분출시켜야 한다. 마지막으로, 소각설비에 연결된 송풍기의 제어반(MCC)에 순간정전 보상장치인 시간지연계전기(TDR: time delay relay)등을 설치하여 순간정전 후에도 자동으로 재가동될 수 있도록 조치해야 한다.

• 생명과학회지
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• 제26권2호
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• pp.220-225
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• 2016

본 연구는 치과 병의원 진료실 주변환경과 치과종사자의 휴대전화에서 분리된 coagulase-negative staphylococci (CNS)의 분리율과 항균제 내성양상 및 분자 역학적 특성을 분석하고자 하였다. 2014년 12월부터 2015년 1월까지 부산지역 10개의 치과 병의원에서 총 154개의 샘플을 수집하여 MALDI-TOF분석법을 통해 동정하였다. 항균제 감수성검사는 디스크 확산법을 시행하였고 mupA, mecA 유전자 보유현황 및 SCCmec type은 PCR과 염기 서열분석에 의해 결정하였다. 154개의 샘플 중 10개(6.5%)에서 CNS 균주(Staphylococcus epidermidis 5주, Staphylococcus capitis 2주, Staphylococcus warneri 2주, Staphylococcus haemolyticus 1주) 가 분리되었다. 항균제 감수성검사에서 penicillin 10주, mupirocin 6주, gentamicin 5주, tetracycline 3주 및 cefoxitin과 erythromycin 2주가 내성이었고 clindamycin, ciprofloxacin, teicoplanin, trimethoprim-sulfamethoxazole에 내성인 세균은 없었다. 2개의 CNS균주(S. warneri, S. haemlyticus)에서 mecA 유전자가 검출되었고 1개의 CNS균주(S. epidermidis)에서 mupA가 확인되었다. Methicillin 내성 CNS균주 가운데 1주는 SCCmec I형이었고 1균주는 SCCmec의 유전형이 구분되지 않았다. 본 연구를 통하여 다약제 내성을 보이는 CNS균주가 더 이상 우리나라 치과병의원 환경에서 드물지 않음을 알 수 있었다.

• Elastomers and Composites
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• 제19권1호
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• pp.13-31
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• 1984

The purposes of this dissertation are to demonstrate that DSC theromoanaytical methods of vulcanization can provide useful informations on the vulcanization characteristics of industrial formulations and also provides the potential basis for a rapid and complete method of sulfur and vulcanizing accelerator analysis for quality control. The influences of those factors such as heating rate, scan temperature, vucanizing accelerator's type and concentration upon vulcanization exotherm in NR and NBR compounds in the presence of vulcanizing accelerators such as TMTD,MBTS,DPG,TMTM,CBS, and MBT were evaluated by means of DSC. In order to examine the credibility in the DSC method, the same samples which were used for DSC method were studied to compare the DSC results with the ODR (Oscillating Disk Rheometer) data. The results obtained were as follows 1. In the DSC dynamic experiments, the observed enthalpy results from vulcanization depends upon the heating rate; In the range of 2 to $20^{\circ}C/min$ of heating rate, as the heating rate was increased the enthalpy change was also increased. However, over the heating rate of $30^{\circ}C/min$ it was observed that the enthalpy change was decreased as the heating rate was further increased. Without regard to the change of enthalpy, tremendous instantaneous heat evolving was observed in the range of high heating rates. 2. For the samples which are added with various vulcanizing accelerators, the activation energies of vulcanization were as follows; 3. Regarding to the influences of vulcanizining accelerator's types upon the characteristics of vulcanization exotherm, NR and NBR compounds in the presence of thiuramsulphide compounds type accelerators such as TMTD, TMTM, were exhibited sharper and higher vulclanization exotherm than others. From the resuts of DSC thermograms which was distributed in even shape in the broad temperature range, it was clearly shown that the guanidine compounds type accelerator such as DPG acts as a delayed acting accelerator. 4. In the comparison of DSC and ODR results, the dependency of temperature in the cure rate and the observed conversions show good agreements between two results. 5. In the same curatives, by the comparison of glass transition temperatures, it was possible to predict relative values of maximum torques. Consequently, from the present studies, it is shown that the DSC thermoanalytical method can provide an alternate new method for rapid and complete quality control analysis of rubber industry.

• 대한임상검사과학회지
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• 제50권4호
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• pp.406-413
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• 2018

최근 P. aeruginosa의 carbapenem에 대한 내성은 전 세계적으로 증가하고 있는 실정이다. 특히 $metallo-{\beta}-lactamases$ (MBLs)는 carbapenem의 고도 내성에 관여하고 있는 것으로 보고되고 있다. 한편, Sequence type 235 (ST235)는 다제내성 클론으로써 국제적으로 보고되고 있으며, IMP-6와 VIM-2 유전자의 확산에도 관여하는 것으로 알려져 있다. 본 연구에서는 2008년 3월부터 2014년 6월까지, 대전지역의 3차 병원에서 분리된 carbapenem 내성 P. aeruginosa에서 MBL 유전자를 분석하고 이에 대한 역학관계를 조사하고자 하였다. 항균제 감수성 양상은 디스크 확산법으로 확인하였고, MBL 유전자의 분석을 위해 PCR과 염기서열분석을 수행하였다. 더불어, 역학 관계를 조사하기 위해 multilocus sequence typing (MLST)를 실시하였다. 110 균주의 carbapenem 내성 P. aeruginosa 중, 32균주(29.1%)가 MBL를 생성하였고, IMP-6 (29균주, 90.6%)가 주요하게 확인되었다. VIM-2는 3균주(9.4%)에서 확인되었으며, 모두 ST357로 확인되었다. IMP-6를 생성하는 P. aeruginosa는 모두 다제내성을 보였고, ST235로 확인되었다. ST235 (55균주, 50.0%)는 가장 높은 비율로 확인된 클론이며 7년 동안 지속적으로 확인되었다. 이러한 다제내성 ST235의 확산을 방지하기 위해, carbapenem의 과도한 사용을 제한하고, 지속적으로 모니터링하는 전략이 개발되어야 할 것으로 사료된다.

• 한국미생물·생명공학회지
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• 제51권4호
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• pp.500-506
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• 2023

Carbapenem 내성 Klebsiella pneumoniae (Carbapenem-resistant K. pneumonia, CRKP)는 전 세계적인 공중 보건 문제로 대두되고 있다. 최근 Klebsiella pneumoniae carbapenemase-2 (KPC-2) 생성 sequence type (ST)307은 CRKP의 주요 클론으로 확인되었으며, 국내에서 ST307의 확산이 보고되었다. 본 연구에서는 2020년 3월부터 2021년 12월까지 대전지역의 3차 병원에서 분리된 CRKP 50균주를 대상으로, 분자 특성과 항균제 내성 양상을 조사하였다. 역학적 관계는 multilocus sequence typing (MLST)를 통해 분석하였고, 항균제 감수성 검사는 디스크 확산법을 통해 확인하였다. PCR과 DNA 염기서열분석은 carbapenemase 유전자 확인을 위해 수행하였다. CRKP감염은 남성과 60세 이상의 환자에서 훨씬 더 빈번하게 확인되었다. CRKP 50균주 중 46균주(92.0%)는 다제내성(MDR)을 보였고, 44균주(88.0%)는 carbapenemase-producing K. pneumoniae (CPKP)로 확인되었다. 주요 carbapenemase 유형은 KPC-2 (36균주, 72.0%)였으며, New Delhi metallo-enzyme-1 (NDM-1)과 NDM-5는 각각 7균주(14.0%)와 1균주(2.0%)에서 확인되었다. 특히, KPC-2 생성 K. pneumoniae의 88.9% (32/36)가 ST307에 속한 반면, NDM-1,-5 생성 K. pneumoniae의 87.5% (7/8)가 non-ST307에 속한 것을 확인하였다. 이러한 결과는 ST307의 확산 뿐만 아니라 non-ST307의 발달을 예방하기 위한 적절한 감염관리와 효과적인 감시체계가 필요하다고 사료된다.

• International Journal of Automotive Technology
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• 제7권4호
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• pp.391-397
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• 2006

The soot yield has been studied by a premixed propane-oxygen-inert gas combustion in a specially designed disk-type constant-volume combustion chamber to investigate the effect of pressure, temperature and turbulence on soot formation. Premixtures are simultaneously ignited by eight spark plugs located on the circumference of chamber at 45 degrees intervals in order to observe the soot formation under high temperature and high pressure. The eight converged flames compress the end gases to a high pressure. The laser schlieren and direct flame photographs with observation area of 10 mm in diameter are taken to examine the behaviors of flame front and gas flow in laminar and turbulent combustion. The soot volume fraction in the chamber center during the final stage of combustion at the highest pressure is measured by the in-situ laser extinction technique and simultaneously the corresponding burnt gas temperature by the two-color pyrometry method. The changes of pressure and temperature during soot formation are controlled by varying the initial charging pressure and the volume fraction of inert gas compositions, respectively. It is found that the soot yield increases with dropping the temperature and raising the pressure at a constant equivalence ratio, and the soot yield in turbulent combustion decreases as compared with that in laminar combustion because the burnt gas temperature increases with the drop of heat loss for laminar combustion.

• Structural Engineering and Mechanics
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• 제37권4호
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• pp.427-442
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• 2011

In fatigue life design of mechanical components, uncertainties arising from materials and manufacturing processes should be taken into account for ensuring reliability. A common practice is to apply a safety factor in conjunction with a physics model for evaluating the lifecycle, which most likely relies on the designer's experience. Due to conservative design, predictions are often in disagreement with field observations, which makes it difficult to schedule maintenance. In this paper, the Bayesian technique, which incorporates the field failure data into prior knowledge, is used to obtain a more dependable prediction of fatigue life. The effects of prior knowledge, noise in data, and bias in measurements on the distribution of fatigue life are discussed in detail. By assuming a distribution type of fatigue life, its parameters are identified first, followed by estimating the distribution of fatigue life, which represents the degree of belief of the fatigue life conditional to the observed data. As more data are provided, the values will be updated to reduce the credible interval. The results can be used in various needs such as a risk analysis, reliability based design optimization, maintenance scheduling, or validation of reliability analysis codes. In order to obtain the posterior distribution, the Markov Chain Monte Carlo technique is employed, which is a modern statistical computational method which effectively draws the samples of the given distribution. Field data of turbine components are exploited to illustrate our approach, which counts as a regular inspection of the number of failed blades in a turbine disk.

• 한국디지털정책학회:학술대회논문집
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• 한국디지털정책학회 2005년도 춘계학술대회
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• pp.107-143
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• 2005

Mobile service that geography, position by development of space Information Technology and technology of communications, space are various to us now becoming limelight as point contents and infra information that customers do demand based on radio superhigh speed authentication net on highly information society by offer infringement problem about individual's privacy or information by political and scientific interest be injured. Purpose of this study grasps use factor of LBS application Mobile service, and it is that analyze actual proof through questionnaire to grasp whether some relation is with value and action determination that is felt of LBS application Mobile service. Distributed all question of 190 copies but disk floret inclination did valid data 171 that clear question and omission remove a lot of questions by type of study among questionnaire of collected 182 wealths. Analyzed factor analysis and authoritativeness to search validity and confidence of questionnaire and used single regression analysis and multiple regression analysis for hypothetical verification. According to verification result, Mobile service that apply position base service usefulness and system quality, adaptedness of Mobile service that apply position base service by leading person affecting in use, acted for connection healthy and felt value is important factor immediately. Usability and social effect, felt expense, privacy did not appear by leading person that keep in mind in this study. Is been related with step that Mobile service that apply position base service is placed. That is, as present childhood, a person who have experience that use service to look for friend is few and usability fairly in last in wide application boundary and this very important person was removed finally in model. This study has sense in terms of study systematically about LBS application service use leading person that is getting into the spotlight worldwide among Mobile service that is injured newly.

• The Journal of Advanced Prosthodontics
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• 제9권2호
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• pp.130-137
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• 2017

PURPOSE. The purpose of this study was to evaluate the effect of nano-structured alumina surface coating on shear bond strength between Y-TZP ceramic and various dual-cured resin cements. MATERIALS AND METHODS. A total of 90 disk-shaped zirconia specimens (HASS CO., Gangneung, Korea) were divided into three groups by surface treatment method: (1) airborne particle abrasion, (2) tribochemicalsilica coating, and (3) nano-structured alumina coating. Each group was categorized into three subgroups of ten specimens and bonded with three different types of dual-cured resin cements. After thermocycling, shear bond strength was measured and failure modes were observed through FE-SEM. Two-way ANOVA and the Tukey's HSD test were performed to determine the effects of surface treatment method and type of cement on bond strength (P<.05). To confirm the correlation of surface treatment and failure mode, the Chi-square test was used. RESULTS. Groups treated with the nano-structured alumina coating showed significantly higher shear bond strength compared to other groups treated with airborne particle abrasion or tribochemical silica coating. Clearfil SA Luting showed a significantly higher shear bond strength compared to RelyX ARC and RelyX Unicem. The cohesive failure mode was observed to be dominant in the groups treated with nano-structured alumina coating, while the adhesive failure mode was prevalent in the groups treated with either airborne particle abrasion or tribochemical silica coating. CONCLUSION. Nano-structured alumina coating is an effective zirconia surface treatment method for enhancing the bond strength between Y-TZP ceramic and various dual-cured resin cements.

• 한국지구과학회지
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• 제31권1호
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• pp.88-94
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• 2010

서안경계류의 발생 역학을 이해하기 위하여 간단한 실험 장치와 방법을 개발하였다. 위도에 따른 코리올리 파라미터의 변화(즉 베타효과)를 구현하기 위하여 바닥이 경사진 반 시계 방향으로 회전하는 수조를 이용하였다. 중위도 해양에 작용하는 바람 응력은 수조 상부에서 시계 방향으로 회전하는 원판으로 대신하였다. 수조 바닥의 형태와 수조의 회전 유무의 조합으로 구성된 4가지 실험을 수행하였다. 그 결과, 베타효과가 포함된 실험에서 서안경계류와 유사한 흐름과 스베드럽 영역을 볼 수 있었다. 반면에, 베타효과 없이 일정한 코리올리 힘만 있을 때는 수조 속의 물은 관성류의 특징을 나타냈다. 우리는 또한 회전 유체가 굳어진 것처럼 변한다는 테일러-프라우드만 효과를 확인 하였다. 이 연구에서 개발된 장치와 방법은 베타효과에 의한 서안경계류를 이해하는 데 도움을 줄 것으로 기대한다.