• International Journal of Control, Automation, and Systems
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• 제1권1호
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• pp.35-42
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• 2003

This paper proposes a simple, robust, nonlinear controller based on Lyapunov stability for tracking the reference welding path and velocity of a two-wheeled welding mobile robot (WMR). The system has three degrees of freedom including two wheels and one torch slider. Torch slider motion is used for faster tracking because the welding speed is very slow. Control law is obtained from the Lyapunov control function to ensure the asymptotical stability of the system. The controller has three free parameters for adjusting the performance of the controlled system. A simple way of measuring the errors using two potentiometers is introduced. The effectiveness of the proposed controller is shown through simulation results.

• Bulletin of the Korean Chemical Society
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• 제29권8호
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• pp.1545-1553
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• 2008

Using a one-pot reaction technique, monodisperse $\gamma-Fe_2O_3$ nanoparticles were prepared by thermal decomposition of Fe$(CO)_5$ in the presence of a long alkyl chain terminated dendron surfactant. The size of the particles is controlled by adjusting the concentration of the dendron ligands in the reaction solution. Spherical, 2 nm sized nanoparticles were obtained with a 3:1 ratio of dendrons to Fe$(CO)_5$, while 4.6 nm sized particles were formed with a 1:3 ratio. Superparamagetic properties of 2 nm, 4 nm, and 4.6 nm sized particles were measured using a SQUID magnetometer.

• 산업공학
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• 제24권4호
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• pp.396-407
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• 2011

We develop a cash management model in which firms face randomly occurred investment projects and retrieve investments upon the maturity of these projects. Using the Markov Decision Problem approach, we examine a control policy which dynamically adjusts the cash balance under the discounted cost criterion. The existence of an optimal policy is shown under some conditions. The optimal solution procedure is developed to find the optimal points and the optimal sizes for adjusting the cash balance. In numerical experiment, we investigate important structural properties of the optimal cash management policy.

• 한국방사선학회논문지
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• 제15권1호
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• pp.9-14
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• 2021

방사선에 의한 피폭 없이 대조도가 우수한 영상의 획득이 가능한 자기공명영상은 진단에 필수적이지만 영상에서의 노이즈 발생은 불가피한 요소이기 때문에 이를 보완하기 위해 자기공명영상장치의 변수들을 조절하여 우수한 특성을 가진 영상을 획득할 수 있다. 이 중, 여기횟수 (NEX; number of excitation)는 추가적인 영상 특성의 저하 없이 우수한 특성의 영상을 획득할 수 있지만 scan time이 증가하여 motion artifact를 발생시킬 수 있고, scan time의 증가에 비례하여 영상의 특성이 향상되지 않기 때문에 적절한 NEX의 설정이 필요하다. 따라서, 본 연구에서는 MRiLab simulation program을 통해 자기공명영상의 모든 변수들을 고정시킨 후, NEX만을 조절하여 획득한 뇌 T2 강조 영상의 정량적 평가를 통해 NEX 변화에 따른 영상 특성의 경향성을 평가하고자 하였다. 획득한 영상의 노이즈 레벨 및 유사도 평가를 하기 위해 신호 대 잡음비 (SNR; signal to noise ratio), 대조도 대 잡음비 (CNR; contrast to noise ratio), 평균 제곱근 오차 (RMSE; root mean square error) 그리고 최대 신호 대 잡음비 (PSNR; peak signal to noise ratio)를 계산하였다. 결과적으로, 노이즈 레벨 및 유사도 평가 인자 모두 NEX가 증가함에 따라 개선된 값을 보였으나, 점차 증가폭이 감소함을 보였다. 따라서, 과도하게 큰 NEX는 장시간의 scan에 따른 motion artifact를 발생시켜 영상 특성을 저하시킬 수 있으므로, 적절한 NEX의 설정이 중요함을 확인하였다.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2001년도 The Pacific Aisan Confrence On Intelligent Systems 2001
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• pp.97-108
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• 2001

Frauds detection is a difficult problem, requiring huge computer resources and complicated search activities Researchers have struggled with the problem. Even though a fee research approaches have claimed that their solution is much better than others, research community has not found 'the best solution'well fitting every fraud. Because of the evolving nature of the frauds. a novel and self-adapting method should be devised. In this research a new approach is suggested to solving frauds in insurance claims credit card transaction. Based on evolutionary computing approach, the method is itself self-adjusting and evolving enough to generate a new self of decision-makin rules. We believe that this new approach will provide a promising alternative to conventional ones, in terms of computation performance and classification accuracy.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2001년도 춘계정기학술대회
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• pp.293-304
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• 2001

frauds detection is a difficult problem, requiring huge computer resources and complicated search activities. researchers have struggled with the problem. Even though a flew research approaches have claimed that their solution is much bettor than others, research community has not found 'the best solution'well fitting every fraud. Because of the evolving nature of the frauds, a Revel and self-adapting method should be devised. In this research a new approach is suggested to solving frauds in insurance claims and credit card transaction. Based on evolutionary computing approach, the method is itself self-adjusting and evolving enough to generate a new set of decision-making rules. We believe that this new approach will provide a promising alternative to conventional ones, in terms of computation performance and classification accuracy.

• 한국미생물·생명공학회지
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• 제17권3호
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• pp.269-272
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• 1989

In order to obtain monoclonal antibody from ascites fluid at sufficiently high purity using a single hydroxylapatite chromatography (HA) a further optimization on its operating variables was carried out. By adjusting the pH of the eluent, the sodium phosphate buffer, to 6.0 from 6.8 and adding CaCl$_2$to 1 mM at the column inlet, the elution molarities (M$_{elu}$) for the desired monoclonal antibody and contaminating proteins can be distinguished from each other with enough resolution. Previously these two groups of proteins co-eluted at the same time at pH 6.8 and without CaCl$_2$. This sin81e step hydroxylapatite chromatography yields the desired antibody pure enough for diagnostic use.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권7호
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• pp.2891-2903
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• 2020

Phase-generated carrier (PGC) demodulation algorithm is the main demodulation methods in Fiber-optic interferometric sensors (FOISs). The conventional PGC demodulation algorithms are influenced by the carrier phase delay between the interference signal and the carrier signal. In this paper, an automatic carrier phase delay synchronization (CPDS) algorithm based on orthogonal phase-locked technique is proposed. The proposed algorithm can calculate the carrier phase delay value. Then the carrier phase delay can be compensated by adjusting the initial phase of the fundamental carrier and the second-harmonic carrier. The simulation results demonstrate the influence of the carrier phase delay on the demodulation performance. PGC-Arctan demodulation system based on CPDS algorithm is implemented on SoC. The experimental results show that the proposed algorithm is able to obtain and eliminate the carrier phase delay. In comparison to the conventional demodulation algorithm, the signal-to-noise and distortion ratio (SINAD) of the proposed algorithm increases 55.99dB.

• 대한통합의학회지
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• 제10권2호
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• pp.95-104
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• 2022

Purpose : This study aimed to investigate the effects of health science majors' communication skills on their adjustment to college life. Methods : The subjects were 336 college students majoring in health science at colleges located in Busan. The survey's questionnaire comprised 38 items, including 15 items for communication skills and 19 items for adjustment to college life. Results : In the gender-based comparison of communication skills and adjustment to college life, female students had better communication skills, with overall higher scores than male students for the understanding others and communication. In the age-based comparison of communication skills and adjustment to college life, students aged 21 to 22 showed the best communication skills, while students aged 18 to 20 exhibited the least communication skills. In terms of adjustment to college life, those aged 25 or older scored the highest, and those aged 21 to 22 scored the lowest. In the school-year-based comparison of communication skills and adjustment to college life, third- and first-year students showed the best and least communication skills, respectively. Overall, third- and fourth-year students were more adjusted at adjusting to college life than first- and second-year students. Third-year students also scored the highest in academic adjustment, whereas second-year students scored the lowest. In terms of relationships between the students' communication skills and their adjustment to college life, communication skills were positively correlated with the following subdomains: understanding of others, self-expression, and communication. Communication skills also showed a positive correlation with adjustment to the college environment, including personal-emotional adjustment. Conclusions : The present study found that communication skills did not significantly affect health science majors' adjustment to college life. However, given that communication skills are an essential factor for effective work performance and greater job satisfaction, it is recommended that colleges provide students with relevant education and experiences to help them enhance communication skills while in school.

• Archives of Pharmacal Research
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• 제10권1호
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• pp.42-49
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• 1987

This study is to evaluate the potential use of aclarubicin-loaded gelatin microspheres as an intravascular biodegradable drug delivery system for the regional cancer therapy. The diameter of the microspheres prepared by water in oil emulsion polymerization could be controlled by adjusting the stirring rate in the range of 10-50 $\mu$m : D(in $\mu$m) = -73.8 log (rpm) + 262.7. The addition of proteolytic enzyme increased the in vitro aclarubicin release but it did not change the amount of the initial burst release which reached about 45%. Microspheres injected intravenously into the mouse tail vein embolized only to the lung when observed by fluorescence microscopy. From histological examination following injection of gelatin microspheres into mouse femoral muscle, mild inflammation was observed from the appearance of neutrophils after 2 days and rapid repair process was confirmed thereafter. Biodegradation process of gelatin microspheres lodged on the pulmonary capillary bed was followed up by microscopic observation; degradation was taking place by about 36 hrs, followed by severe damage on the spheerical shape and microspheres was no longer found 10 days after injection.