• 반도체디스플레이기술학회지
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• 제13권1호
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• pp.13-17
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• 2014

Since the semiconductor manufacturing requires the silicon wafers with extraordinary degree of surface flatness, the surface polishing of wafers from ingot cutting is an important process for deciding surface quality of wafers. The present study introduces the development of wafer polishing equipment and, especially, the wafer polishing head that employs the forced self-driving of installed silicon wafer as well as the wax wafer mounting technique. A series of wafer polishing tests have been carried out to investigate the effects of self-driving function in wafer polishing head. The test results for wafer planarization showed that the LLS counts and SBIR of polished wafer surfaces were generally improved by adopting the self-driven polishing head in wafer polishing stations.

• 한국산업보건학회지
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• 제15권2호
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• pp.104-113
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• 2005

A variety of ergonomic assessment methods of lifting tasks known as a major cause of work-related lower back pain have been used. But there is a limited information in choosing the most appropriate assessment method for a particular job and in finding out strengths and weakness of the methods. The purpose of this study was to assess and compare the ergonomic risks of lifting tasks in a marine diesel engine production industry by three lifting ergonomic assessment tools widely used: the National Institute for Occupational Safety and Health(NIOSH) Revised Lifting Equation(NLE), the Washington Administrative Code 296-62-0517(WAC), and the Snook Tables. Lifting index(weight of load/Recommended Weight Limit) of NLE($LI_{NLE}$) was above 1 at 34 tasks(75.6%) of a total number of 45 lifting tasks. LI of WAC($LI_{WAC}$) was above 1 at 11 tasks(24.4 %). LI of Snook Table($LI_{Snook}$) was above 1 at 29 tasks(64.4%). Thus, LI was high in orders of $LI_{NLE}$ > $LI_{Snook}$ > $LI_{WAC}$. There were significantly high correlations among three Lls(p<0.01). The correlation coefficients between $LI_{NLE}$and the other three Lls($LI_{WAC}$ and $LI_{Snook}$) were r=0.93 and r=0.88, respectively. The linear regression equations were y = 0.444x + 0.11(r=0.93) between $LI_{NLE}$ and $LI_{WAC}$, y = 0.93x + 0.008(r=0.88) between LI(NLE) and $LI_{Snook}$. The LI values by WAC was significantly lower than those by the other tools. The compared features, strength and limitation among these tools were described in this paper.

• Quantitative Bio-Science
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• 제36권1호
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• pp.23-31
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• 2017

Datasets from DNA microarray experiments, which are in the form of large matrices of expression levels of genes, often have missing values. However, the existing statistical methods including the principle components analysis (PCA) and Hotelling's t-test are not directly applicable for the datasets having missing values due to the fact that they assume the observed dataset is complete in general. Many methods have been proposed in previous literature to impute the missing in the observed data. Troyanskaya et al. [1] study the k-nearest neighbor (kNN) imputation, Kim et al. [2] propose the local least squares (LLS) method and Rubin [3] propose the multiple imputation (MI) for missing values. To identify differentially expressed genes, we propose a new testing procedure when the missing exists in the observed data. The proposed procedure uses the Stouffer's z-scores and combines the test results of individual imputed samples, which are dependent to each other. We numerically show that the proposed test procedure based on MI performs better than the existing test procedures based on single imputation (SI) by comparing their ROC curves. We apply the proposed method to analyzing a public microarray data.

• Transactions on Electrical and Electronic Materials
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• 제11권5호
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• pp.238-241
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• 2010

The purpose of this study is to solve the problems of radio frequency bandwidth frequency depletion, confusion possibilities, and security that are in current wireless communications systems, and to confirm the possibility of applying those solutions for the next generation network. To solve the problems of the current wireless communications system, a visible light communications system for power line communication (PLC) via 8-bit microcontroller is created and the capacity is analyzed. The exclusive PLC chip APLC-485MA, an 8-bit ATmega16 microcontroller, high brightness 5pi light emitting diodes (LEDs), and the LLS08-A1 visible light-receiving sensor were used for the transmitter and receiver. The performance was analyzed using a designed program and an oscilloscope. The voltage change was measured as a function of distance from 10-50 cm. Blue LEDs showed the best performance among the measured LED types, with 0.47 V of voltage loss, but for a distance over 50 cm, precise data was not easy to obtain due to the weak light. To overcome these types of problems, specific values such as the changing conditions and efficiency value relevant to the light emitting parts and the visible light-receiving sensor should be calculated, and continuous study and improvements should also be realized for better communication conditions.

• 전기학회논문지
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• 제59권11호
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• pp.2043-2047
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• 2010

This study is to solve problems of depletion of RF bandwidth frequency, confusion possibility, security that current wireless communications system have and is to confirm possibility of applying next generation network. To solve problems of current wireless communications system, visible light communications system for power line communications using ATmega16 Microcontroller is was realized and receiver property was analyzed. PLC exclusive chip APLC-485MA, Microcontroller ATmega16, 5pi bulb type LED and high flux LED, visible light receiving sensor LLS08-A1 were used for transmitter and receiver. Performance was analyzed by designed program and an oscilloscope. It was showed average 20% improved receiver rate rather than bulb type LED in the case of high flux LED through voltage change rate on communication distance and LED type of distance between 10 to 50 cm. The blue LED showed the best performance among measured LED types with above 10% of voltage decreasing rate. But As it gradually becomes more distant, the precise date was difficult to obtain due to weak light. To overcome these sort of problems, specific values such as changing conditions and efficiency value relevant to light emitting parts and visible light receiving sensor should be calculated and continuous study and improvements should also be accomplished for the better communications condition.

• 폴리머
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• 제31권6호
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• pp.461-468
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• 2007

폴리에스터와 trisilanolisobutyl polyhedral oligomeric silsesquioxane(TBPOSS)으로 제조된 나노복합재료에 존재하는 응집체의 구조를 이해하기 위하여 SEM-EDS 분석과 1,1,1,3,3,3-hexafluoro-2-propanol(HFIP) 용매에 녹인 뒤 레이저 광산란법이 실시되었다. SEM에서 평균 직경 120 nm로 나타난 구형 응집체는 가교화된 마이크로겔이 아니라, 320개의 TBPOSS 분자들과 폴리에스터 분절들이 교대로 연결된 선형 중합체 사슬(무게평균 분자량=$2.3{\times}10^6\;g/mol$)이며, 이들은 매트릭스의 폴리에스터와의 화학조성 차이 때문에 상분리된 것으로 여겨진다. 반면에 무게평균 분자량이 $4.0{\times}10^4\;g/mol$인 매트릭스의 폴리에스터는 분자당 2.5개의 TBPOSS 분자를 포함하고 있는 것으로 나타났다. 또한 넣어준 TBPOSS의 약 93%가 매트릭스에 존재하며 나머지 7%는 구형 응집체에 분포하고 있다는 것도 밝혀졌다.

• Biomolecules & Therapeutics
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• 제9권3호
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• pp.201-208
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• 2001

The present study was conducted to examine the effects of cholinergic stimulation and membrane depolarization on secretion of epinephrine (EP) and norepinephrine (NE) in the perfused model of the rat adrenal gland and to investigate the effect of bromocriptine on secretion of EP and NE evoked by these secreta-gogues. Acetylcholine (ACh, 5.32 mM), high $K^{+}$(56mM), 1.1-dimethyl-4-phenyl piperazinium iodide (DMPP, 100 $\mu$M for 2 min), (3-(m-cholro-phenyl-carbamoyl-oxy)-2butynyl trimethyl ammonium chloride (McN-A-343, 100 $\mu$M for 2 min), cyclopiazonic acid (10 $\mu$M for 4 min) and methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl) -pyridine-5-carboxylate (Bay-K-8644, 10 $\mu$M for 4 min) evoked a 1.3~5.3-fold greater secretion of EP than NE in the perfused rat adrenal gland. The perfusion of bromocriptine (1-10 $\mu$M) into an adrenal vein for 20 min produced relatively dose-dependent inhibition in secretion of EP and NE evoked by ACh, high $K^{+}$, DMPP, and McN-A-343. Moreover, under the presence of bromocriptine (1~10 $\mu$M), releasing responses of EP and NE evoked by cyclopiazonic acid and Bay-K-8644 were also greatly reduced. Taken together, these results suggest that cholinergic stimulation and membrane depolarization enhance more release of EP than NE in the perfumed rat adrenal medulla, and that bromocriptine inhibits the release of EP and NE evoked by stimulation of cholinergic receptors as well as by membrane depolarization. It seems that this inhibitory effect of bromocriptine is associated with inhibition of calcium channels through activation of dopaminergic D2-receptors located in the rat adrenomedullary chromaffin cells.lls.

• 한국식품과학회지
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• 제30권4호
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• pp.941-947
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• 1998

전통안동식혜로부터 젖산균 L. bulgaricus LBS 47, L. acidophilus LAS 10 및 Lc. lactis LLS 56와 효모 S. cerevisiae SCS 5을 분리하였다. 분리동정한 균들의 pH, 적정산도 및 균수의 변화를 관찰한 결과, SCS 균주는 배양 4시간에 pH 4.5으로 가장 낮았으며 LBS과 LAS 균주의 적정산도는 배양 초기 $0.40{\sim}2.30%$로 SCS 균주보다 큰 변화를 나타내었다. LBS과 LAS 균주의 성장변화는 두 균주 모두 배양 20시간에 $1.7{\times}10^9{\;}CFU/mL$로 성장 정지기에 도달하였다. SCS 균주는 배양 12시간에 $4.8{\times}10^6{\;}CFU/mL$로 정지기에 도달하여 SCS 균주가 LBS과 LAS 균주에 비해 균 성장은 유사하였으나 균수에 있어서는 낮은 결과를 나타내었다. 효모 SCS 균주의 최적 성장온도는 $30^{\circ}C$로 나타났다. pH와 적정산도는 배양 12시간에 pH 4.5와 적정산도 1.23%의 빠른 산생성을 보였으며, 균수의 변화는 배양 32시간에 $4.9{\times}10^9{\;}CFU/mL$로 성장정지기에 도달하였다.

• 한국통신학회논문지
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• 제40권1호
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• pp.88-95
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• 2015

본 논문은 비선형적 최소제곱법을 위한 효율적인 위치추정기법 연구를 하였다. 비선형적 최소제곱 방식은 선형적 최소제곱 방식에 비해 정확도가 높으며 거리 오차에 대해서 보다 강인한 추세를 보이지만 회기적인 방법을 취하기 때문에 계산 량이 매우 많아지는 단점이 있다. 본 논문에서는 비선형적 최소제곱 위치 추정 방식인 Newton method와 Levenberg-Marquardt 방식을 이용하였을 때 추정 위치 정확도와 복잡도 간의 기회비용 관점에서 효율적인 알고리즘을 제시하여 계산 량을 줄이면서 성능 열화를 방지할 수 있는 기법을 제시하였다. 시뮬레이션 결과로 추정 위치 정확도와 회기(iteration) 횟수를 구하고 선형적 방식의 위치 추정 성능, 기존의 비선형적 방식, 제안한 방식에 대해 비교 분석하여 제안한 알고리즘을 검증하였다.

• 한국세라믹학회지
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• 제39권6호
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• pp.582-588
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• 2002

Ti 기판에 TiO$_2$ 중간층을 플라즈마 용사법으로 증착 후 IrO$_2$-RuO$_2$ 박막을 졸-겔과 dip coating법으로 제조하였다. 코팅 층의 접착력을 향상시키기 위하여 유기화합물과 glass brit을 첨가하였다. Taguchi법의 망대특성과 Lls(2$^1$$\times$3$^{7}$ )의 직교배열표를 이용하여 IrO$_2$-RuO$_2$ 박막의 최적조건인 인자와 수준 조합의 최적화를 전류밀도를 측정 분산분석하였다. 최적의 코팅조건은 각각 ethyl cellulose의 점도는 100cp, 건조온도 및 시간은 17$0^{\circ}C$ 20분, 열처리온도 및 시간은 75$0^{\circ}C$ 10분, 전도성 분말과 glass frit의 무게비는 99:5, 최종열처리시간은 120분, 주입산소량은 5sccm이었다. 분산분석결과, 유의수준이 $\alpha$=0.1인 통계적으로 90%신뢰공정이었다.