• Restorative Dentistry and Endodontics
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• 제27권1호
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• pp.24-33
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• 2002

Leakage studies have been performed frequently, since a fluid-tight seal provided by various dental fill-ing materials has been considered clinically important. The leakage of the various root-end filling materials has been widely investigated mostly dye penetration method. These dye studies cannot offer any information about the quality of the seal of a test material over a long period of time The purpose of this study was to evaluate the microleakage of root end cavities in blood contamination filed amalgam, intermediate restorative material(IRM), light cured glass ionomer cement(GI) and mineral trioxide aggregate(MTA) by means of a modified fluid transport model. Fifty standard human root sections, each 5mm high and with a central pulp lumen of 3mm in diameter, were and filled with our commonly used or potential root end fill ing materials after they were contaminated with blood. At 24h. 72h, 1, 2, 4, 8, and 12 weeks after filling, leakage along these filling materials was determined under a low pressure of 10KPa(0.1atm) using a fluid transport model. The results were as follows : 1 MTA group showed a tendency of decreasing percent of gross leakage (20m1/day) in process of time, whereas the other materials showed a tendency of increasing in the process time. 2. At the all time interval, GI group leaked significantly less than amalgam group and IRM group (p＜0.05). 3. At the 4 weeks, the percentage of gross leakage in MTA group decreased to 0% thereafter, the low per-centage of gross leakage was maintained in MTA group until the end of the experiment, whereas the percentage in IRM group increased to 100% 4. At the 12 weeks, percentage of gross leakage was significantly low in MTA group(0%), comparison with GI group(40%), amalgam group(90%) and IRM group(100%), but there was no significant difference between latter two materials.

• Restorative Dentistry and Endodontics
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• 제27권1호
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• pp.16-23
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• 2002

Physical properties of composite resins such as strength, resistance to wear, discoloration, etc depend on the degree of conversion of the resin components. The purpose of this study was to evaluate the degree of conversion of the composite resins according to the thickness of tooth structure penetrated by light and applied light curing time. The coronal portions of extracted human teeth (one anterior tooth, three posterior tooth) was embedded by pink denture material. the mounted teeth were cut into three illumination sections (1mm thickness enamel section, 1mm thickness dentin section, 2mm thicknes dentin section) and one backing section with cutting wheel. Thin resin films were made by using 6kg pressure between slide glass during 5 minutes Thin resin film was light cured on coupled illumination section during 40sec, 80sec and 120sec. each illumination section was coupled as follows; no tooth structure(X), ename section(E), enamel section + 1mm dentin section(ED1), enamel section + 2mm dentin section(ED2), enamel section + 1mm dentin section + 2mm dentin section(EDD). To simulate the clinical situation more closely, thin resin films was cured against a backing section of tooth structure. The degree of conversion of carbon double bonds to single bonds in the resin films were examined by means of Fourier Transform Infrared Spectrometer. The results were obtained as follows ; 1 As curing time was increased, conversion rate was increased and as tooth thickness which was penetrated by curing light was increased, conversion rate was decreased. 2. At all tooth thickness groups, conversion rate between 80sec and 120sec was not significantly increased(P＞0.05). 3. At 40sec group and 80sec, conversion rate between no tooth structure(X) group and 1mm enamel section(E) group was not significantly decreased(P＞0.05). 4. At 80sec group and 120sec, conversion rate between 1mm enamel section(E) group and 1mm enamel section + 1mm dentin section(ED1) group was not significantly decreased(P＞0.05).

• 유통과학연구
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• 제14권3호
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• pp.73-83
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• 2016

Purpose - The parcel delivery service(courier) industry all over the world has been expanding its market so far, but its growth has been declining in recent years. In this situation, most parcel delivery companies are having trouble with managing themselves because of the pressure from the customer to increase service level and decrease the rate. The purpose of this study is to provide ways to improve competitive advantages of the parcel delivery service industry by evaluating the multi-period operating efficiency of Korea, Japan and global service providers. Research design, data, and methodology - The data for the period of 2011 to 2014 were collected from the annual reports published by parcel delivery companies. In this study, we analyze the marketability (revenue), profitability (operating profits), and management conditions (net profits) of parcel service companies by combining information on human resources (number of employees) and material resources (total assets and equity). Therefore, the number of employees, total assets, and equity are selected as input variables, and revenue, operating profits, and net profits as the output variables. In this study, DEA (Data Envelopment Analysis) is used to measure the comparative efficiency and MPI (Malmquist Productivity Index) is used to analyze the trend of change of the efficiency for a multi-year period. Results - The operational efficiency scores of medium-sized parcel delivery companies in Korea are higher than other larger competitors such as Korean, Japan and Global larger companies. As of 2014, Logen(1.878) was found to be the most efficient parcel delivery enterprise, followed by KGB (1.224), and Kyoungdong(1.002). Otherwise, Hanjin(0.235), CJ(0.262), Hyundai Logistics(0.657), DHL(0.611), UPS(0.766), FedEx(0.498), TNT(0.350), Yamato(0.762) and Sagawa(0.520), larger sized companies, were done inefficiently. The productivity of parcel delivery companies is influenced by endogenous factors as well as exogenous ones such as changes in business environment and technological advances. Conclusions - Korean medium-sized companies have relatively high efficiency scores in operation. That is why they still survive the competitive market in Korea where market restructuring on the industry has been expected to be conducted for many years. The reason why medium-sized couriers had higher efficient scores than larger couriers is that most of couriers spend more operating expenses versus unit price of delivery which is the amount of money that is needed in order to send a package by parcel service. So the delivery unit price must be taken into account by all the expenses associated with the cost of fuel, labor and maintenance expenses for facilities, etc. therefore, the unit price must be increased to strengthen business competitive power. In order for the industry to have more competitive advantage, the companies need to make profits by increasing demand volume and raising the delivery rate to provide high-quality delivery service to customers. And both endogenous and exogenous change must take precedence in order to strengthen their competitiveness.

• 시큐리티연구
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• 제37호
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• pp.165-195
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• 2013

오늘날 현대 조직에서는 제3의 자본으로서 사회자본의 중요성이 부각되고 있다. 사회자본은 조직구성원에 대한 효율적 인적 자원관리와 관련하여 "구성원에 대한 신뢰와 규범, 사회적 네트워크"등을 그 구성요소로 하는데, 현재 이와 관련된 많은 연구들이 활발하게 진행되고 있다. 하지만 아직까지 민간경비업체 종사자들의 사회자본에 대한 연구는 찾아보기 어려운 실정이다. 이에 이 연구에서는 사회자본에 대한 국내외 선행연구를 바탕으로 민간경비업체 종사자들을 대상으로 하여, 사회자본과 직무만족과의 관계에 대해서 직무특성의 매개역할을 중심으로 한 실증분석을 통해 민간경비업체 종사자들의 효율적 관리방안을 제시하고자 하였다. 이 연구의 결과, 첫째, 사회자본과 직무만족과의 관계에 대한 분석결과, 사회자본의 구성요소 중 신뢰와 네트워크는 직무만족에 유의미한 영향을 미치는 것으로 나타났다. 둘째, 사회자본과 직무만족과의 관계에서 직무특성에 대한 매개효과의 분석결과, 직무특성 요인인 직무중요성과 기술다양성은 매개효과가 있는 것으로 나타났다. 이러한 실증분석의 결과는 민간경비업체 종사자들의 직무스트레스를 감소시켜 주고 직무만족과 더불어 조직의 성과를 향상시키기 위해서는 조직 구성원 간의 신뢰와 네트워크 등을 통하여 사회자본에 기반을 둔 상호협력 등이 필요로 함을 의미한다. 따라서 민간경비업체 종사자들에 대한 사회자본의 활성화와 유지를 위한 관리전략이 모색되어야 할 것이다.

• 한국식품과학회지
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• 제42권4호
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• pp.390-397
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• 2010

Residual solvents in foods are defined as organic volatile chemicals used or produced in manufacturing of extracts or additives, or functional foods. The solvents are not completely eliminated by practical manufacturing techniques and they also may become contaminated by solvents from packing, transportation or storage in warehouses. Because residual solvents have no nutritional value but may be hazardous to human health, there is a need to remove them from the final products or reduce their amounts to below acceptable levels. The purpose of this study was to develop and evaluate an analytical method for the screening of residual solvents in health functional foods. Furthermore, the aim of this study was to constitute a reasonable management system based on the current state of the market and case studies of foreign countries. Eleven volatile solvents such as MeOH, EtOH, trichloroethylene and hexane were separated depending on their column properties, temp. and time using Gas Chromatography (GC). After determining the GC conditions, a sample preparation method using HSS (Head Space Sampling) was developed. From the results, a method for analyzing residual solvents in health functional foods was developed considering matrix effect and interference from the sample obtained from the solution of solvents-free health functional foods spiked with 11 standards solutions. Validation test using the developed GC/HSS/MS (Mass Spectrometry) method was followed by tests for precision, accuracy, recovery, linearity and adequate sensitivity. Finally, examination of 104 samples grouped in suits was performed by the developed HSS/GC/MS for screening the solvents. The 11 solvents were isolated from health functional foods based on vapor pressure difference, and followed by separation within 15 minutes in a single run. The limt of detection (LOD), limit of quantification (LOQ), recovery and coefficient of variation (C.V.) of these compounds determined by the HSS/GC/MS were found to be 0.1 pg/mL, 0.1-125 pg/g, 51.0-104.6%, and less than 15%, respectively. Using the developed HSS/GC/MS method, residual solvent from 16 out of 104 health functional products were detected as a EtOH. This method therefore seems t o be a valuable extension ofanalytical method for the identification of residual solvents in health functional food.

• Applied Biological Chemistry
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• 제49권4호
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• pp.293-297
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• 2006

포유류의 조직에 널리 분포되어 있으며 혈압 조절에 중요한 역할을 하는 Angiotensin-converting enzyme(ACE)은 아연을 함유하는 dipeptidase로서 angiotensin I을 가수분해하여 강력한 혈압상승제인 angiotensin II를 생성하는 효소이다. 최근에 돼지의 난소에서 ACE 활성이 측정되었으며, 돼지의 신장에서 ACE 단백질이 분리되어 그 특성이 알려졌다. 그러나 돼지의 어떠한 ACE DNA 염기서열도 아직까지 보고 된 바는 없다. 그러므로 본 연구에서 reverse transcriptase-polymerase chain reaction(RT-PCR)을 이용하여 돼지의 신장 ACE cDNA를 클로닝하고 그 염기서열을 분석하였다. ACE cDNA는 1309개의 아미노산으로 구성되어 있으며 그 분자량은 150kDa이다. 염기서열로부터 유추한 아미노산의 서열을 분석한 결과, N 말단의 33개 아미노산이 signal peptide 역할을 하는 것으로 보이며, C 말단 근처의 짧은 transmembrane 영역은 세포막에 anchor역할을 하는 것으로 보인다. 돼지 신장의 ACE에서 두 개의 매우 유사한 amino acid peptidase domain은 tandem duplication 되어 있으며, 각각의 domain은 다른 포유류의 체세포 ACE들과 마찬가지로 putative metal-binding site(His-Glu-Met-Gly-His)를 하나씩 가지고 있는 것으로 나타났다. 돼지 신장 ACE 서열과 인간, 토끼, 쥐 등과 같은 포유류의 ACE 아미노산 서열들과의 상동성 비교는 진화과정 중 두 domain이 매우 잘 보전되어 왔음을 보여주고 있다.

• 대한한방내과학회지
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• 제26권1호
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• pp.182-198
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• 2005

Object : This study was designed to research whether the protection and inhibitory effects of cardiovascular diseases in L-NAME induced rat or ECV 304 cell lines through the Cell morphological pattern, Tunel assay, LDH activity, heart rate, blood pressure and immunohistochemistric analysis by Boonsimgieum water extract Methods : Nitric oxide(NO) play an important role in normal and pathophysiological cells including as a messenger molecule, neurotransmitter, microbiocidal agent, or dilator of blood vessels and artheriosclerosis, hypertension, myocardial infarction, respectively. Endothelial cell products can modulate the magnitude of a response to a vasoconstrictor, as evinced by the greater constriction after endothelium removal or NO synthesis blockade. To investigate that Boonsimgieum in the potential contribution of the levels of nitric oxide generated by endothelial nitric oxide synthase (eNOS) and the mechanisms of protection against NG-nitro-L-arginine methyl ester (L-NAME), human ECV 304 cells, which normally do not express eNOS, were expressed by L-NAME. L-NAME stimulated rat or cells were found to be resistant to injury and delayed death following the Boonsimgieum. Inhibition of nitric oxide synthesis abolished the protective effect against L-NAME, thrombin and collagen exposure. Interestingly, such effects have been observed during stimulation with agents such as phenylephrine and KCl on L-NAME mediate rats, were damaged by the NOS inhibitor L-NAME. Result : As the result of this study, In group, the anti-apoptosis and necrosis in the cardiovascular system have a potential capacity for prevented, protected and treating the diseases of cardiovascular system, against the necrosis of rat and ECV 304 cells with Caspase 3 and calpain expression by L-NAME is promoted. Conclusion : these results demonstrate neuroprotective and memory enhancing effects of ZIBU, suggesting its beneficial actions for the treatment of AD.

• 한국콘텐츠학회논문지
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• 제12권9호
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• pp.57-67
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• 2012

배우가 어떤 과정을 통해 인물이 되는가에 관해서는 많은 혼란이 존재한다. 인물이 되어야 한다는 압박감은 배우들로 하여금 자신을 저버리고 무작정 다른 존재가 되도록 요구하고, 그에 따라 인위적이고 상투적인 연기의 함정에 빠지기 쉽다. 모든 예술은 정직하게 자기 자신에게서 시작된다. 벗어날 수 없는 일상속에 얽매인 나와 무한한 가능성을 지닌 자유로운 존재로서의 나를 구분해야만 어떻게 나에게서 시작해서 나를 버리고 나를 넘어설지를 모색할 수 있다. 살아있는 인물이 되고자 하는 배우는 연기하려고 하지 말고, 경험하려고 하여야 한다. 경험하기 위해서는 반응해야 한다. 반응하기 위해서는 오감의 경험에서 시작하여야 한다. 인물도 우리 모두와 마찬가지로, 오감의 경험에 반응하고, 반응에 반응하면서, 그리고 상상력이 빚어내는 이미지들에 반응하면서 세상에 존재하고 살아가는 것이다. 배우는 자신의 감각과 기억, 그리고 상상력만을 가친 채 극적 상황이라는 가상의 절박한 상황에 던져진다. 낯선 상황에 직면해 알지 못하는 것에 대한 두려움을 갖는 것은 자연스러운 일이나, 그 두려움에 억매여 있으면 아무것도 제대로 하지 못한다. 경험을 해가면서 인물을 내 몸과 마음이 저절로 이해하게 해야 한다. 알아서 하는 것이 아니라, 모르기 때문에 하는 것이고, 하면서 그리고 하기 때문에 알게 되는 것이다. 인물이 된다는 것은 미지의 여행에서 새로운 경험을 하면서 새로운 나를 끊임없이 발견하는 것이다.

• 한국미생물·생명공학회지
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• 제42권3호
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• pp.258-266
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• 2014

고구마 소주는 전분과 섬유질이 많은 고구마를 발효시킨 후 상압증류하여 제조되어 특유의 부드러운 맛과 향미를 가진다. 본 연구에서는 별도의 용도가 없어 폐기되고 있는 고구마 소주 주박의 효율적인 이용을 위해, 주박의 ethanol 및 열수 추출물을 조제하고 이들을 순차적 유기용매 분획하여 각각의 hexane, ethylacetate (EA), butanol 분획물과 물 잔류물을 조제하여 각 시료의 항균 및 항혈전 활성을 평가하였다. 그 결과, 주박의 ethanol 추출 효율이 열수 추출 효율보다 1.36배 높았으며, 분획물 중에서는 EA 분획물이 가장 높은 total polyphenol 함량을 나타냄을 확인하였다. 고구마 소주 주박의 추출물 및 분획물(0.5 mg/ml)은 인간 적혈구에 대한 용혈활성을 나타내지 않았으며, 열수 및 ethanol 추출물의 EA 분획물에서만 광범위 항세균 활성과 강력한 혈액응고 저해 활성이 나타났다. 또한 혈소판 응집저해 활성의 경우 열수 추출물의 EA 분획에서만 아스피린과 유사한 응집저해를 나타내었다. 본 연구결과는 폐기되고 있는 고구마 소주 주박의 열수 추출물의 EA 분획이 신규의 항세균 및 항혈전제로 개발될 수 있음을 제시하고 있다.

• 한국응용과학기술학회지
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• 제33권1호
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• pp.118-128
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• 2016

대기오염에 관한 관심은 국내 외에서 점진적으로 상승하고 있으며, 자동차와 연료 연구자들은 청정(친환경 대체연료) 연료와 연료품질 향상 등을 이용하여 새로운 엔진 설계, 혁신적인 후 처리 시스템 등의 많은 접근을 통하여 차량 유해 배기가스를 감소시키려고 노력하고 있다. 이러한 연구들은 가솔린 자동차의 배출가스 및 가솔린 차량의 PM 입자 배출 등의 두 가지 이슈로 진행되고 있다. 자동차의 배출가스 및 PM(입자상 물질) 입자는 환경오염과 인체에 악영향을 주는 많은 문제를 일으키고 있다. 추가로, 함산소 첨가제로서 연료에 포함된 MTBE (Methyl Tertiary Butyl Ether)에 대한 환경 문제점을 연구하고 있다. 연구자들은 MTBE가 건강에 미치는 영향에 대한 많은 데이터를 가지고 있다. 이러한 데이터는 높은 MTBE 용량에서 잠재적인 발암 물질 임을 결론짓고 있다. 함산소 연료첨가제 유형 (MTBE, 바이오 ETBE, 바이오 에탄올, 바이오 부탄올)에 기초하여, 본 논문은 가솔린 연료 물성 및 증발가스 배출 특성에 대해 산소함량의 영향을 검토하였다. 또한, 연료물성에 대한 휘발유 차량의 가속 및 출력 성능을 평가하였다.