• 소성∙가공
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• 제19권1호
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• pp.11-16
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• 2010

The influence of pre-strain on low cycle fatigue behavior of Fe-18Mn-0.05Al-0.6C TWIP steel was studied by conducting axial strain-controlled tests. As-received plates were deformed by rolling with reduction ratios of 10 and 30%, respectively. A triangular waveform with a constant frequency of 1 Hz was employed for low cycle fatigue test at the total strain amplitudes in the range of ${\pm}0.4\;{\sim}\;{\pm}0.6$ pct. The results showed that low-cycle fatigue life was strongly dependent on the amount of pre-strain as well as the strain amplitude. Increasing the amount of prestrain, the number of reversals to failure was significantly decreased at high strain amplitudes, but the effect was negligible at low strain amplitudes. A new model for predicting fatigue life of pre-strained body has been suggested by adding ${\Delta}E_{pre-strain}$ to the energy-based fatigue damage parameter. Also, high-cycle fatigue lives predicted using the low-cycle fatigue data well agreed with the experimental ones.

• 전자공학회논문지
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• 제50권1호
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• pp.131-136
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• 2013

칩 적층기술의 발달로 TSV(Through Silicon Via) 기반 3D IC가 개발되었다. 3D IC의 높은 신뢰성과 수율을 얻기 위해서는 pre-bond 와 post-bond 수준에서 다양한 TSV 테스트가 필수적이다. 본 논문에서는 pre-bond 다이의 TSV 연결부에서 발생하는 미세한 고장과 post-bond 적층된 3D IC의 TSV 연결선에서 발생하는 다양한 고장을 테스트할 수 있는 설계기술을 소개한다. IEEE 1500 표준 기반의 래퍼셀을 보완하여 TSV 기반 3D IC pre-bond 및 post-bond의 at speed test를 통하여 known-good-die와 무결점의 3D IC를 제작하고자 한다.

• 종양간호연구
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• 제12권1호
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• pp.110-116
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• 2012

Purpose: This study was performed to identify the pre-and post-transplant nutritional assessment for patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). Methods: The subjects of this study were 25 patients undergoing allogeneic HSCT. The data collection was performed from January 31st to March 31st, 2011. The Patient-Generated Subjective Global Assessment (PG-SGA), anthropometrics and biochemical test were collected from the time they entered the isolation unit until they left. Results: Pre-transplant nutritional assessment status indicated moderate malnutrition which scored $7.32{\pm}1.68$ in PG-SGA. There were 22 patients (88.0%) with moderate malnutrition and 3 patients (12.0%) with severe malnutrition. Post-transplant nutritional assessment indicated severe malnutrition status which scored $11.92{\pm}3.26$ in PG-SGA. Pre-and post-transplant nutritional assessment displayed significant differences (p<.001) in PG-SGA score. Hematopoietic stem cell transplantation led to a deterioration of patients' nutritional status. Pre-transplant patients were already in malnutrition status and patients undergoing allogeneic HSCT were at risk for malnutrition. Conclusion: Pre-and post-transplant patients were categorized as having undernutritional and malnutritional status. Pre-transplant nutrition status impacted on post-transplant nutritional status. Health care personnel should pay attention to patient's nutrition status when undergoing allogeneic HSCT with appropriate nutritional assessment tools.

• 한국임상수의학회지
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• 제4권2호
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• pp.483-490
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• 1987

In order to study the compensatory renal function in 6 Korean black goats with 75% reduction in renal mass, some blood chemical values were determined and pathological changes were examined. The results were as follows : 1. BUN level increased significantly from post-operation day 1 through day 30(p<0.01) compared with pre-operation level. Serum creatinine level increased significantly from post-operation day 1 through day 26(p <0.01 ) compared with pre-operation level and remained higher than pre-operation level at day 30(p <0. 05). 2. Serum calcium level increased significantly from post-operation day 4 through day 7(p<0.01) compared with pre-operation level and remained higher than pre-operation level from post-operation day 8 through day 14(p<0.05). Serum phosphorus level decreased at postoperation day 4,5(p<0.05 ) compared with pre-operation level. 3. RBC counts decreased at post-operation day 2. 3, 5. to 30(p<0.05), PCV decreased at post-operation day 2, 3, 5, 7, to 30(p<0.05), hemoglobin level decreased at post-operation day 2, 8, 14, to 30(p<0.05), compared with pre - operation levels, respectively. 4. The ventral half of the right kidney was infarcted by the ligation of ventral branch of right renal artery.

• 한국유체기계학회 논문집
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• 제20권1호
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• pp.21-28
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• 2017

Optimization process of pre-swirl nozzle geometry was conducted to improve the discharge coefficient of pre-swirl system by using CFD. The optimization of pre-swirl nozzle shape covered the converging angle and the location of the converging nozzle. Optimization process included Optimal Latin Hyper-cube Design method to get the experimental points and the Kriging method to create the response surface which gives candidate points. The process was finished when the difference between the predicted value and CFD value of candidate point was less than 0.1 %. This paper compared the Reference model, Initial model which is the first model of optimization and Optimized model to study flow characteristics. Finally, the discharge coefficient of Optimized model is improved about 17 % to the Reference model.

• 전기학회논문지
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• 제63권5호
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• pp.676-682
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• 2014

In this paper, precipitation echo(PRE) and non-precipitaion echo(N-PRE)(including ground echo and clear echo) through weather radar data are identified with the aid of neuro-fuzzy algorithm. The accuracy of the radar information is lowered because meteorological radar data is mixed with the PRE and N-PRE. So this problem is resolved by using RBFNN and judgement module. Structure expression of weather radar data are analyzed in order to classify PRE and N-PRE. Input variables such as Standard deviation of reflectivity(SDZ), Vertical gradient of reflectivity(VGZ), Spin change(SPN), Frequency(FR), cumulation reflectivity during 1 hour(1hDZ), and cumulation reflectivity during 2 hour(2hDZ) are made by using weather radar data and then each characteristic of input variable is analyzed. Input data is built up from the selected input variables among these input variables, which have a critical effect on the classification between PRE and N-PRE. Echo judgment module is developed to do echo classification between PRE and N-PRE by using testing dataset. Polynomial-based radial basis function neural networks(RBFNNs) are used as neuro-fuzzy algorithm, and the proposed neuro-fuzzy echo pattern classifier is designed by combining RBFNN with echo judgement module. Finally, the results of the proposed classifier are compared with both CZ and DZ, as well as QC data, and analyzed from the view point of output performance.

• 대한교통학회지
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• 제27권1호
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• pp.43-51
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• 2009

이 논문은 타이어-노면간 마찰계수(drag factor)와 노면에 발생된 스키드마크를 통해 제동직전 속도(pre-braking speed) 산정을 정확하게 하기 위한 방법론을 제시하고자 한다. 제동직전 속도(pre-braking speed)와 활주직전 속도(pre-skidding speed)간 어떠한 상관관계가 있는지 판단하기 위해 실차 주행 및 제동실험을 통해 데이터가 수집되었다. 두 대의 차량에 fifth wheel(오륜) 장비, 스피드건, vericom 2000 등 다양한 측정장비를 탑재하여 제동실험이 수행되었으며, 자동차 속도, 제동거리, 활주거리, 감속도 등이 정밀 측정되었다. 실험자료의 분석을 통해 노면 마찰계수값과 활주직전 속도를 산정하고, 이후 활주직전 속도와 제동직전 속도를 비교하여 이들간의 상관관계를 규명하였다. 결과적으로 산정된 마찰계수값은 현재 일반적으로 적용되고 있는 0.8보다 높았으며, 제동직전 속도는 활주직전 속도보다 $5{\sim}10km/h$ 정도 높은 것으로 나타났다. 향후에는 다양한 차종과 노면조건에 대한 후속실험을 통해 더욱 정교한 한국형 분석모형의 개발과 실무적용이 필요할 것으로 판단된다.

• 한국위성정보통신학회논문지
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• 제6권2호
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• pp.20-25
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• 2011

저자는 참고문헌 [2]에서 복수의 송신안테나를 이용한 두 가지 Pre-Rake 송신다이버시티 방법 (system 1과 system 2)을 제안하였고 이론적인 해석과 컴퓨터 시뮬레이션을 통해 제안 시스템의 성능을 분석하였다. 그러나, 참고문헌 [2]에서는 전체 안테나를 이용하여 송신하는 system 2 에 대하여 다중사용자 환경을 고려한 성능 평가가 이루어지지 않았다. 따라서 본 논문에서는 다중사용자 환경에 대하여 system 2의 성능을 이론적으로 해석하고 한 개의 안테나를 선택하여 송신하는 system 1의 성능과 비교한다. 두 시스템의 성능평가 결과를 통해 사용자 수가 적을 때는 system 1이 좋은 성능을 보이며 사용자 수가 많아질수록 system 2가 system 1보다 좋은 성능을 나타내는 사실을 밝힌다. 이로써 사용자 수에 따라 Pre-Rake 송신다이버시티 타입을 기지국에서 선택하여 전송하는 것이 최상의 시스템 성능을 얻기 위해 필요함을 제시한다.

• 분석과학
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• 제35권3호
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• pp.129-135
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• 2022

본 연구는 alumina, leucine, alumina와 leucine을 9:1로 혼합한 분말(이하 Al-Leu (9:1)), alumina와 leucine을 5:1로 혼합한 분말(이하 Al-Leu (5:1)), alumina와 sodium lactate를 5:1로 혼합한 분말(이하 Al-Lac (5:1))을 자연상태 시료지문을 남긴 후 1, 7, 14, 30일로 노화시킨 잠재지문에 전처리한 후 cyanoacrylate fuming(이하 CA 훈증법)으로 현출 증강을 시도하였다. 전체적으로 미처리한 후 CA 훈증한 잠재지문보다 alumina, leucine, Al-Leu (9:1), Al-Leu (5:1), Al-Lac (5:1) 분말로 전처리한 잠재지문의 면적값과 특징점 개수가 향상되었다. 따라서 5종류의 개시제가 CA 훈증 시 현출 증강을 향상시키는 것을 확인하였다.

• Journal of Information Technology Applications and Management
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• 제15권2호
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• pp.33-49
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• 2008

The purpose of this study is to find student factors associated with the students' evaluation of university teaching, and to provide a meaningful reference to policy-making of teaching evaluation. Based on the surveyed questionnaires from 232 students who participated in e-learning course. in combination with applying descriptive statistics, this study analyzes (1) the influences of students' pre-motivation level of student based-on ARCS theory on class satisfaction, (2) the influences of students' grade, attendance, and class involvement on class satisfaction, and (3) the influences of e-learning experience on students' pre-motivation level and class satisfaction. Result of this study shows that: (1) students' pre-motivation level including Attention(A), Relevance(R), Confidence(C), and Satisfaction(S) is positively correlated to students' evaluation for teaching, (2) students' grade, attendance. and class involvement are positively correlated to students' evaluation for teaching, and (3) students' e-learning experience is not related with students' pre-motivation level, whereas it is related with class satisfaction.