• 한국도로학회논문집
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• 제9권4호
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• pp.193-204
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• 2007

변형강도($S_D$)는 고온에서 아스팔트 혼합물의 소성변형특성과 상관관계가 높은 특성이며, APA 시험기는 아스팔트 혼합물의 소성변형저항성 평가에 널리 이용된다. 따라서 $S_D$를 이용한 아스팔트 혼합물의 소성변형저항성 추정에 상응하는 값으로 APA 시험 결과가 사용되었으며 $S_D$와 APA의 상관관계를 설정하기 위하여 많은 데이터가 수집되었다. 아스팔트 공시체를 $60^{\circ}C$에 30분간 수침한 후 50mm/min의 하중을 가하여 최대하중 P와 그때의 수직변형 y로 부터 $S_D$를 계산하였다. 같은 혼합물에 대하여 APA 시험도 수행되었다. APA 침하깊이와 $S_D$간의 회귀분석을 수행하여 $R^2=0.76$이 얻어졌다. 이는 변형강도 시험이 아스팔트 혼합물의 고온변형 저항성을 추정 가능한 시험법임을 암시하는 것이다. 또한 회귀분석 모델을 이용하여 특정 등급도로의 표층 및 기층 혼합물 $S_D$의 임계값을 설정할 수 있음을 보였다. 이를 더 정교하게 연구하면 이 임계치는 특정층 포장혼합물의 하한치로 이용될 수 있을 것이다.

• 한국운동역학회지
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• 제15권3호
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• pp.143-152
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• 2005

The purpose of this study was to predict the failure or success of the Snatch-lifting trial as a consequence of the stand-up phase simulated in Kane's equation of motion that was effective for the dynamic analysis of multi-segment. This experiment was a case study in which one male athlete (age: 23yrs, height: 154.4cm, weight: 64.5kg) from K University was selected The system of a simulation included a multi-segment system that had one degree of freedom and one generalized coordinate for the shank segment angle. The reference frame was fixed by the Nonlinear Trans formation (NLT) method in order to set up a fixed Cartesian coordinate system in space. A weightlifter lifted a 90kg-barbell that was 75% of subject's maximum lifting capability (120kg). For this study, six cameras (Qualisys Proreflex MCU240s) and two force-plates (Kistler 9286AAs) were used for collecting data. The motion tracks of 11 land markers were attached on the major joints of the body and barbell. The sampling rates of cameras and force-plates were set up 100Hz and 1000Hz, respectively. Data were processed via the Qualisys Track manager (QTM) software. Landmark positions and force-plate amplitudes were simultaneously integrated by Qualisys system The coordinate data were filtered using a fourth-order Butterworth low pass filtering with an estimated optimum cut-off frequency of 9Hz calculated with Andrew & Yu's formula. The input data of the model were derived from experimental data processed in Matlab6.5 and the solution of a model made in Kane's method was solved in Matematica5.0. The conclusions were as follows; 1. The torque motor of the shank with 246Nm from this experiment could lift a maximum barbell weight (158.98kg) which was about 246 times as much as subject's body weight (64.5kg). 2. The torque motor with 166.5 Nm, simulated by angular displacement of the shank matched to the experimental result, could lift a maximum barbell weight (90kg) which was about 1.4 times as much as subject's body weight (64.5kg). 3. Comparing subject's maximum barbell weight (120kg) with a modeling maximum barbell weight (155.51kg) and with an experimental maximum barbell weight (90kg), the differences between these were about +35.7kg and -30kg. These results strongly suggest that if the maximum barbell weight is decided, coaches will be able to provide further knowledge and information to weightlifters for the performance improvement and then prevent injuries from training of weightlifters. It hopes to apply Kane's method to other sports skill as well as weightlifting to simulate its motion in the future study.

• Journal of Chest Surgery
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• 제44권1호
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• pp.44-50
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• 2011

Background: Cardiovascular complications are major causes of morbidity and mortality following non-cardiac thoracic operations. Recent studies have demonstrated that elevation of N-Terminal Pro-B-type natriuretic peptide (NT-proBNP) levels can predict cardiac complications following non-cardiac major surgery as well as cardiac surgery. However, there is little information on the correlation between lung resection surgery and NT-proBNP levels. We evaluated the role of NT-proBNP as a potential marker for the risk stratification of cardiac complications following lung resection surgery. Material and Methods: Prospectively collected data of 98 patients, who underwent elective lung resection from August 2007 to February 2008, were analyzed. Postoperative adverse cardiac events were categorized as myocardial injury, ECG evidence of ischemia or arrhythmia, heart failure, or cardiac death. Results: Postoperative cardiac complications were documented in 9 patients (9/98, 9.2%): Atrial fibrillation in 3, ECG-evidenced ischemia in 2 and heart failure in 4. Preoperative median NT-proBNP levels was significantly higher in patients who developed postoperative cardiac complications than in the rest (200.2 ng/L versus 45.0 ng/L, p=0.009). NT-proBNP levels predicted adverse cardiac events with an area under the receiver operating characteristic curve of 0.76 [95% confidence interval (CI) 0.545~0.988, p=0.01]. A preoperative NT-proBNP value of 160 ng/L was found to be the best cut-off value for detecting postoperative cardiac complication with a positive predictive value of 0.857 and a negative predictive value of 0.978. Other factors related to cardiac complications by univariate analysis were a higher American Society of Anesthesiologists grade, a higher NYHA functional class and a history of hypertension. In multivariate analysis, however, high preoperative NT-proBNP level (>160 ng/L) only remained significant. Conclusion: An elevated preoperative NT-proBNP level is identified as an independent predictor of cardiac complications following lung resection surgery.

• 한국진공학회지
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• 제12권4호
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• pp.239-250
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• 2003

실리콘-게르마늄 이종접합 바이폴라 트랜지스터 (SiGe HBT)에서 발생하는 신뢰성 열화 현상을 고찰하였다. SiGe HBT의 경우에 전류이득 감소, AC특성 저하, 오프셋 전압이 자주 관찰되는데 그 원인으로는 각각 에미터-베이스 역 바이어스 전압 스트레스, 과도촉진확산 (transient enhanced diffusion), 공정 변동 (fluctuation)에 따른 베이스-콜렉터 접합 특성 저하를 들 수 있다. 에미터-베이스 접합에 역 바이어스 전압 스트레스가 걸리면 에미터-베이스 접합면의 테두리 부분에서 높은 에너지를 가지는 전자와 정공들이 생성되고, 이들 전자와 정공들이 실리콘-산화막 계면 및 산화막 내부에 전하를 띈 트랩을 생성하기 때문에 재결합에 의한 베이스 누설전류가 증가하여 소자의 전류이득은 크게 감소하게 된다. 에미터-베이스 접합과 외부 베이스의 거리가 임계 값보다 짧을 때에는 소자의 차단주파수($f_t$)가 감소하게 되는데 이것은 외부 베이스 이온주입에 의하여 내부 베이스 내의 도펀트의 확산이 촉진되어 나타나는 현상이다. 외부 베이스 이온주입 에너지가 충분하지 않은 경우에는 콜렉터-베이스 접합의 턴온 전압이 감소하여 전류-전압 특성 곡선에서 오프셋 전압이 발생하게 된다.

• 식물병연구
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• 제12권2호
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• pp.134-138
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• 2006

2003년부터 2004년 평창 지역의 브로콜리 포장에서 새로운 병해가 발견되었다. 유묘 감염이 되었을 때 떡잎의 주위로부터 검게 변색되기 시작하여 결국 떡잎이 떨어지고 유묘는 죽었다. 성체에서는 잎 가장자리로부터 엽맥을 타고 진전되어 V 자 또는 U 자형의 노란색 병반을 형성하였다. YDC 배지에서 병원세균을 순수 분리하였을 때 Xanthomonas 속 세균의 전형적인 특정인 노란색 색소를 띤 세균이 형성되었다. 분리된 세균을 $10^8 cfu/ml$로 현탁 한후 3 주 동안 자란 브로콜리, 양배추, 배추, 케일, 무에 가위 접종하여 병원성을 확인하였다. 지방산 조성 및 함량, 다양한 탄소원 이용정도 및 16S rDNA 염기서열를 이용하여 분리세균 SL4797 과 SL4800 을 대조균주 X. campestris pv. campestris NCPPB528 과 비교하였을 때 매우 유사하였다. 이 논문은 국내에서 브로콜리의 검은썩음병 최초 보고이다.

• Parasites, Hosts and Diseases
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• 제25권2호
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• pp.141-148
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• 1987

실험적으로 폐홉춘을 감염시킨 백서의 혈청내 항원을 ELISA 법으로 측정하였다. 시험용 혈청은 폐흡충의 피낭유충을 마리당 25개씩 먹인 총 22마리의 백서에서 감염후 12주가 될 때까지 채혈하여 얻었다. 폐흡충에 대한 특이항체는 폐흡충 감염 고양이의 혈청으로부터 ammonium sulfate 침전과 anionezchange chromatography를 이용, IgG를 분리한 후 affinity chromatography를 이용하여 순수분리하였다. 항원을 찾기 위한 ELISA는 소위 "double antibody sandwich method"를 사용하였다. 대조로서 사용한 감염전 혈청의 O.D.치 평균값은 0.04(표준편차 0.04)이었으며 감염후 O.D.치 (표준편차)의 변화를 보면 0.5주(3일)는 0.03(0.01), 1주는 0.55(0.50), 1.5주는 0.69(0.45), 2주는 0.20(0.19), 2.5주는 0.13(0.10)이었고 감염 3주 이후는 대조 혈청의 값으로 떨어졌다. 대조혈청의 $평균간+3{\times}$ 표준편차, 즉 0.16이하를 이 system에서의 비특이적 수치로 잡았을 때 이 이상의 수치를 나타낸 경우는 감염 후 1주부터 2.5주까지의 혈청에서만 관찰되었다. 한편 감염 12주 후에 총 10마리의 백서를 희생시켜 유충을 회수하여 보았다. 폐와 흉강에서는 평균 2.2마리, 근육에서는 평균 6.2마리의 유충을 회수할 수 있었다. 폐흡충 감염 백서에 있어 충체가 생산하는 항원은 감염 1주 후부터 혈청 내에서 검출되었다. 그러나 감염 3주후부터는 검출되지 않았는데 이것은 항원-항체 복합체 형성에 의한 반응 저해 현상에 의한 것으로 생각되었다.

• 식물조직배양학회지
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• 제27권3호
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• pp.185-189
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• 2000

카사바 (Manihot esculenta Crantz, cv. MCol 22)의 마디 절편을 MS 기본배지에 3종류의 사이토키닌을 여러 농도로 첨가한 조건에서 2주동안 현탁배양한 결과, 고체배지에서 3주 배양된 것보다 훨씬 생장이 효과적이었다. 현탁배양된 유식물에서는 과수화현상이 나타났으나, 이들을 세사 (마사토 + 1/2농도의 크놉씨액)를 담은 유리배양병에 이식하여 생육시킨 결과, 유경에서 새 잎이 신장되면서 과수화를 벗어나 4주후에는 4~6개의 마디를 가진 유경길이 3~5 cm의 정상 유묘로 생장됨으로서, 목본식물인 카사바의 경우 마디절편의 현탁배양에 의한 대량증식의 가능성을 확인했다. 현탁배양시 저농도의 제아틴 (0.01-0.05 mg 1$^{-1}$) 처리는 BAP 최적조건에서 보다 2배나 길게 부정아 길이를 신장시켰다. 사이토키닌 처리로 부정아가 잘 발생된 유식물은 토양이식 작업을 간편하게 했으며, 토양 이식 후 부정근을 활발히 발생시켜 one step culture시스템 배양이 가능하게 했다. 과수화된 유식물은 기외에서 순화가 어려웠으나 유기물이 혼입되지 않은 세사를 담은 유리배양병에서는 비무균조건일지라도 95% 이상 순화될 수 있었다.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제18권1호
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• pp.10-16
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• 2015

Purpose: The aim of this study is to investigate the changing prevalence rate of Helicobacter pylori infection in children, of different age groups, with recurrent abdominal pain over a 10-year period. Methods: Children with recurrent abdominal pain who visited the pediatric outpatient clinic at university hospital were screened for H. pylori. Children were divided into 3 age categories of 4-5, 6-11, and 12-16 years. To study the changes in the annual prevalence rates of H. pylori infection, the study period was divided into 3 time periods: 2004-2007, 2008-2010, and 2011-2014. Urea breath test was performed for all children aged 4-16 years, with a cut-off value of 4.0‰ for children aged ${\geq}6$ years and 7‰ for children aged <6 years. Results: A total of 2,530 children (1,191 boys) with a mean age of $10.0{\pm}3.0years$ (range, 4.0-16.9 years) were included in the study. The total prevalence of H. pylori infection was 7.4% (187/2,530). The prevalence rate of H. pylori infection in children with recurrent abdominal pain was 8.0% (70/873) in 2004-2007, 7.7% (51/666) in 2008-2010, and 6.7% (66/991) in the 2011-2014. Nevertheless, a significant difference was observed in the prevalence rate between children <12 years old and ${\geq}12$ years of age (p=0.018). Conclusion: The prevalence of H. pylori infection in Korean children with recurrent abdominal pain was 7.4%, showing no significant decrease in the last 11 years; however, the prevalence rate in children <12 years old was significantly lower than that in those ${\geq}12$ years old.

• Journal of Preventive Medicine and Public Health
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• 제35권2호
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• pp.99-106
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• 2002

Objective : Until now, there have been no evidence-based guidelines produced for the mass screening of hyperlipidemia cases in Korea. This study was done to find the most efficient strategy for a hyperlipidemia-screening program among Korean adults, Method : Seven alternative strategies for hyperlipidemia screening were formulated and compared ir terms of cost-effectiveness. Cost and effectiveness were estimated from social perspectives and using a two-stage screening process (initial testing and additional testing for positives from the first test). A computerized database (based on persons who had visited a health promotion center in one teaching hospital for a routine health check-up) was used to determine the cost and the outcome of various strategies. Official data was used in calculating direct and indirect costs. Effectiveness was measured according to the number of persons who needed clinical intervention for hyperlipidemia. A stratified analysis, considering age group and sex, was then done. Sensitivity analyses, focusing on several uncertain parameters, were also done. Results : Of the seven test alternatives available, the most cost-effective strategy was a screening program, which consisted of an initial test of total cholesterol, high-density lipoprotein cholesterol and triglyceride. There was some variation in the rank of the cost-effectiveness ratios for the seven alternatives dependent on age group or gender. Conclusions : Current hyperlipidemia screening practice, for National Health Insurance beneficiaries, tests only the total cholesterol level with a cut-off value of 260mg/dl as an initial screening test. It is not the best strategy for cost-effectiveness, and should be modified. Different screening strategies taking age group and sex into account should be developed and used for the efficient mass screening of hyperlipidemia cases among Korean adults.

• 생명과학회지
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• 제15권6호
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• pp.851-856
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• 2005

Although valuable microbes have been isolated from the soil for the various productions of useful components, the microbes which can be cultivated in the laboratory are only $0.1-1\%$ of all microbes. To solve this problem, the study has recently been tried for making the valuable components from the environment by directly separating unculturable micrbial DNA in the soil. But it is known that humic acid originated from the soil interrupts various restriction enzymes and molecular biological process. Thus, in order to prevent these problems, this study modified the method separated soil DNA with phenol, CTAB and PEG. In order to compare the degree of purity for each DNA and the molecular biological application process, $A_{260}/A_{280}$ ratio, restriction enzymes, and PCR were performed. In case of DNA by the modified method, total yield of DNA was lower but $A_{260}/A_{280}$ ratio was higher than the previously reported methods. It was confirmed that the degree of purity is improved by the modified method. But it was not cut off by all kinds of tested restriction enzymes because of the operation of a very small amount of interrupting substances. When PCR was operated with each diluted DNA in different concentrations and GAPDH primer, the DNA by the modified method could be processed for PCR in the concentration of 100 times higher than by the previously reported separation method. Therefore, this experiment can find out the possibility of utilization for the unknown substances by effectively removing the harmful materials including humic acid and help establishing metagenomic DNA library from the soil DNA having the high degree of purity.