• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.729-737
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• 1996

Laminated composite plates have been applied to aircraft structures because their properties are superior to the conventional materials and the laminates have anisortropic elastic properties. However, it tis diffcult to determine stacking structures using actual design variables for the lack of searching capability of existing optimization technique. GA(generic algorithms) are robust search algorithms based on the mechanics of natural selection and natural genetics. Therefore, this study presents an application of IGA to stiffness and weight optimization design and gives the various stacking structures suitable to constraint conditions.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.27-30
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• 2007

This study considers the feasibility of the concentration control of the methanol solution by oscillating flow in the anode channel of passive type Direct Methanol Fuel Cells(DMFC). DMFC stack performance is largely influenced by the fuel concentration. If the fuel concentration is either lower than 0.5M or more than 2M, its performance deteriorates seriously because of the fuel starvation or the fuel crossover. In this respect the optimization of the fuel concentration is crucially important to maximize the DMFC stack performance. In this work, the effects of oscillating actuation in the fuel supply are studied to control the fuel concentration. Two important nondimensional parameters are introduced, each of which represents either the oscillating frequency or the oscillating amplitude. It is shown how these factors affect the stack performance and the efficiency of the DMFC stack.

• International Journal of Air-Conditioning and Refrigeration
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• 제13권2호
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• pp.83-88
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• 2005

This study investigates the air leakage and heat transfer characteristics of a commercially available rotary-type air-to-air heat exchanger with a fiber polyester matrix. Crossover leakage between the exhaust and supply air is measured using a tracer gas method for various ventilation rates and rotational speeds of the wheel. A correlation equation for the leakage is obtained by summing up pressure leakage and carryover leakage. The pressure leakage is observed to be a function of ventilation rate only, and the carryover leakage is found to be a linear function of wheel speed. The real efficiency of the heat exchanger can be obtained from its apparent efficiency by taking into account the leakage ratio. The heat recovery efficiency decreases, as the ventilation rate increases. As the wheel speed increases, however, the efficiency increases initially but reaches a constant value for the speeds over 10rpm.

• Korean Journal of Computational Design and Engineering
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• 제6권3호
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• pp.174-183
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• 2001

This study proposes an improved genetic algorithm (GA) to derive solutions for facility layout problems having inner walls and passages. The proposed algorithm models the layout of facilities on a flour-segmented chromosome. Improved solutions are produced by employing genetic operations known as selection, crossover, inversion, mutation, and refinement of these genes for successive generations. All relationships between the facilities and passages are represented as an adjacency graph. The shortest path and distance between two facilities are calculated using Dijkstra's algorithm of graph theory. Comparative testing shows that the proposed algorithm performs better than other existing algorithm for the optimal facility layout design. Finally, the proposed algorithm is applied to ship compartment layout problems with the computational results compared to an actual ship compartment layout.

• Journal of the Korea Society of Computer and Information
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• 제22권11호
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• pp.143-149
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• 2017

In this paper, we propose efficient management method of liberal education for improving computer literacy. We analyzed the actual conditions and factors affecting education and reflected the analysis results in education. The subject of the study is 'Practice Excel', and tested achievement based on computer literacy. In order to evaluate objectively, we conducted CBT(Computer Based Test) based on Computer Specialist in Spreadsheet & Database Level-2. Analysis of the questionnaire included the use of the popular statistical program, IBM SPSS 24 trial, and frequency, ANOVA, t-test, crossover analysis, and correlation. Evaluation results, An important factor influencing educational performance was active participation. It also proved to be very helpful for understanding excel functions & expression.

• Journal of Korean Academy of Fundamentals of Nursing
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• 제26권2호
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• pp.136-143
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• 2019

Purpose: The feasibility and differential effects of two music therapy methods (interventions with preferred music vs. classical relaxation music) were done to examine the effects on agitation and anxiety in patients weaning off mechanical ventilation. Methods: This pilot study was conducted using a crossover design. Six patients listened to preferred music choices and classical relaxation music. Anxiety scores were measured using the Richmond Agitation Sedation Scale (RASS), State-Trait Anxiety Inventory (STAI), and visual analog scale (VAS). Results: Patients showed a significant decrease in agitation and anxiety after both the preferred and classical relaxation music interventions. The difference in the effects of preferred music and that of classical relaxation music was not significant. As for feasibility, patients exhibited a change in agitated behaviors after the music interventions by not trying to take off medical devices and quietly listening to the music, and by smiling and moving lips along with the lyrics while listening. Conclusion: Music interventions which centered on either patients' preferences or classical relaxation music to enhance relaxation, helped reduce agitation and anxiety during the mechanical ventilation weaning process.

• Journal of Pharmaceutical Investigation
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• 제37권5호
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• pp.315-321
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• 2007

The purpose of the present study was to evaluate the bioequivalence of two lercanidipine hydrochloride tablets, Zanidip tablet (LG Life Sciences Ltd., Korea, reference drug) and Samchundang Lercanidipine tablet 10 mg (Sam Chun Dang Pharm. Co. Ltd., Korea, test drug), according to the guidelines of Korea Food and Drug Administration (KFDA). After adding an internal standard (amlodipine maleate) to human serum, serum samples were extracted using hexan-isoamyl alcohol (100:1, v/v). Compounds were analyzed by liquid chromatography/tandem mass spectrometry. This method showed linear response over the concentration range of 0.05-20 ng/mL with correlation coefficient of 0.9999. The lower limit of quantitation using 0.5 mL of serum was 0.05 ng/mL which was sensitive enough for pharmacokinetic studies. Thirty healthy male Korean volunteers received each medicine at the lercanidipine hydrochloride dose of 20 mg in a $2\;{\times}\;2$ crossover study. There was a one-week washout period between the doses. Serum concentrations of lercanidipine were monitored by an LC/MS/MS fer over a period of 24 hr after the administration. $AUC_t$ (the area under the serum concentration-time curve from time 0 to 24 hr) was calculated by the linear trapezoidal rule method. $C_{max}$ (the maximum serum drug concentration) and $T_{max}$ (the time to reach $C_{max}$) were compiled from the serum concentration-time data. Analysis of variance was carried out using logarithmically transformed $AUC_t$ and $C_{max}$. No significant sequence effect was found for all of the bioavailability parameters, indicating that the crossover design was properly performed. The 90% confidence intervals of the $AUC_t$ ratio and the $C_{max}$ ratio for Samchundang Lercanidipine/Zanidip were log 0.9505-log 1.2258 and log 0.9987-log 1.2013, respectively. These values were within the acceptable bioequivalence intervals of log 0.80-log 1.25. Thus, the criteria of the KFDA guidelines for the bioequivalence was satisfied, indicating Samchundang Lercanidipine tablet 10 mg and Zanidip tablet are bioequivalent.

• Journal of Pharmaceutical Investigation
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• 제40권2호
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• pp.125-131
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• 2010

A bioequivalence study of LANIDIEM$^{(R)}$ tablet 4 mg (Samil. Co., Ltd.) to Vaxar$^{(R)}$ tablet 4 mg (GlaxoSmithKline Co., Ltd.) was conducted according to the guidelines of Korea Food and Drug Administration (KFDA). Forty healthy male Korean volunteers were enrolled in the study and thirty six volunteers completed the study according to the protocol. Thirty six volunteers received each medicine at the lacidipine dose of 4 mg in a $2{\times}2$ crossover study. There was one week wash-out period between the doses. Plasma concentrations of lacidipine were monitored by a high performance liquid chromatography - tandem mass spectrometry (LC-MS/MS) for over a period of 24 hours after drug administration. $AUC_t$ (the area under the plasma concentration-time curve from time zero to 24 hr) was calculated by the linear trapezoidal rule method. $C_{max}$ (maximum plasma drug concentration) and $T_{max}$ (time to reach $C_{max}$) were compiled from the plasma concentration-time data. Analysis of variance was carried out using logarithmically transformed $AUC_t$ and $C_{max}$. No significant sequence effect was found for all of the bioavailability parameters indicating that the crossover design was properly performed. The 90% confidence intervals of the $AUC_t$ ratio and the $C_{max}$ ratio for LANIDIEM$^{(R)}$/Vaxar$^{(R)}$ were log 0.8102~log 1.0417 and log 0.8493~log 1.1439, respectively. These values were within the acceptable bioequivalence intervals of log 0.80~log 1.25. Thus, our study demonstrated the bioequivalence of LANIDIEM$^{(R)}$ tablet 4 mg and Vaxar$^{(R)}$ tablet 4 mg with respect to the rate and extent of absorption.

• Journal of Acupuncture Research
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• 제36권4호
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• pp.272-276
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• 2019

Background: The purpose of this study was to assess the accuracy and safety of procedures using ultrasound equipment for acupuncture treatment. Methods: A pilot, prospective randomized, single blinded, crossover clinical study on the accuracy and safety of ultrasound-guided Gyeontonghyeol (BP-LE6) acupuncture treatment was conducted. Patients (n = 13) with shoulder pain were randomly divided into 2 groups. During Visit 1, ultrasound-guided BP-LE6 acupuncture was administered to the experimental group. In the control group, patients received BP-LE6 acupuncture (without checking ultrasound images) by manipulating the ultrasound probe as if administering ultrasound-guided acupuncture. Visit 2 was arranged within 7-14 days and the remaining procedures, other than those administered in Visit 1, were performed. In both the experimental group and control group, the number of needle insertions, and time required for the treatment to result in the patients feeling de-qi was recorded. The numeric rating scale (NRS) score for shoulder pain was recorded before and after the acupuncture treatment. Results: The number of needle insertions was $5.31{\pm}3.50$ times in the experimental group, and $6.62{\pm}3.38$ times in the control group, however, there was no statistically significant difference between the groups (p > 0.05). The mean time required to perform the procedure was $151.54{\pm}48.59$ seconds in the experimental group and $86.69{\pm}37.17$ seconds in the control group, which was statistically significantly different (p < 0.05). The changes observed in numerical rating scale scores between groups were not statistically significantly different. Conclusion: Although there was no statistically significant difference, administering acupuncture using ultrasound guidance may lead to accurate needling with a reduced number of needle insertion attempts. A large-scale clinical study of better design should be conducted in the future.

• Journal of agricultural medicine and community health
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• 제31권2호
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• pp.119-144
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• 2006

The Korea rural health study, a large prospective cohort study, the objectives of this study are exploration for potential causes of agricultural injuries and diseases among farmers. Current medical research suggests that they may have higher rates of some traumatic injuries, pesticide poisoning, infectious diseases, musculoskeletal diseases, asthma and other respiratory diseases. This study is designed to identify occupational, lifestyle, and environmental factors of workplace that may affect the rate of diseases in farming population. Round 1, initial cohort recruitment, will begin in 2006 and conclude in 2009. Round 2, follow-up will begin in 2010 and conclude in 2014. Approximately 54,000 persons will be selected to study population. Nested case-control studies and case-crossover studies will be conducted for getting to the bottom of agriculture-related diseases. Recruitment and follow-up are conducted in collaboration with multi-centers. As data on the exposures and health outcomes of this study population are collected and analyzed in 2014. This study will be evaluated by public health experts for effort, achievement, adequacy of performance, efficacy, process of study and so on. The author expects that this cohort study may reduce agricultural injuries and diseases and will provide information that agricultural workers can use in making decisions about their health. Also, this study will be significant basis for strengthening the competitiveness of agriculture in Korea.