• Journal of KSNVE
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• v.8 no.5
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• pp.964-973
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• 1998

In this paper we propose a levitation and imbalance compensation controller design methodology of magnetic bearing system. In order to achieve levitation and elimination of unbalance vibartion in some operation speed we use the discrete-time Q-parameterization control. When rotor speed p = 0 there are no rotor unbalance, with frequency equals to the rotational speed. So in order to make levitatiom we choose the Q-parameterization controller free parameter Q such that the controller has poles on the unit circle at z = 1. However, when rotor speed p $\neq$ 0 there exist sinusoidal disturbance forces, with frequency equals to the rotational speed. So in order to achieve asymptotic rejection of these disturbance forces, the Q-parameterization controller free parameter Q is chosen such that the controller has poles on the unit circle at z = $exp^{ipTs}$ for a certain speed of rotation p ( $T_s$ is the sampling period). First, we introduce the experimental setup employed in this research. Second, we give a mathematical model for the magnetic bearing in difference equation form. Third, we explain the proposed discrete-time Q-parameterization controller design methodology. The controller free parameter Q is assumed to be a proper stable transfer function. Fourth, we show that the controller free parameter which satisfies the design objectives can be obtained by simply solving a set of linear equations rather than solving a complicated optimization problem. Finally, several simulation and experimental results are obtained to evaluate the proposed controller. The results obtained show the effectiveness of the proposed controller in eliminating the unbalance vibrations at the design speed of rotation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.101-109
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• 1997

The present study was carried out to investigate the temporal and spatial changes in species composition and abundance of polychaetes in Lake Shihwa. Macrobenthic fauna were collected from eight sampling surveys performed in March, June, September and December of 1994, March and October of 1995, February and August of 1996, using a modified van Veen grab with 0.1 $m^2$ coverage area. Polychaete worms, the most abundant macrofaunal group, comprised of 1~22 species at each investigation; number of species continuously decreased during the survey period. The mean density of polychaete was $794{\pm}1,275\;indiv.{\cdot}m^{-2}$ and showed a large fluctuation over time. The variation in abundance was mainly coupled with the domination of Polydora ligni occupying 83% in total density. The next dominant species were Pseudopolydora kempi (mean density of 31 $indiv.{\cdot}m^{-2}$) and Capitella capitata (mean density of 23 $indiv.{\cdot}m^{-2}$). Abundant polychaetes in Lake Shihwa are known to be tolerant to sediment pollution. Ecological indices such as diversity (H') and dominance (D) also indicated that the number of species significantly decreased and a few species predominated in Lake Shihwa after the dike construction. The azoic zone were extended from the upper reach of Lake Shihwa to the vicinity of the dike over time. The reduced number of species, predominance of pollution indicator species and development of an azoic zone reflect severe deterioration of benthic environments in Lake Shihwa.

• Korean Journal of Ecology and Environment
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• v.40 no.4
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• pp.503-510
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• 2007

The purposes of the study were to analyze the seasonal effects on the fish fauna and compositions including trophic guilds and tolerance guilds. For the study, we collected fish samples twice in June as premonsoon period and early September 2007 as monsoon periods in five sampling sites of the Gap Stream, and then biological oxygen demand (BOD), nutrients (TN, TP) and suspended solids (SS) were compared with the guild data along the gradient of upstream-to-downstream. Chemical water quality, based on BOD, TP, and TN degraded gradually from the upstream to downstream reach and there were about 3 fold difference between S1 and S5. Water quality was worse in the premonsoon than the monsoon, and the heavy monsoon resulted in a dilution of the polluted river by rain water, especially, in the downstream reach. Total number of fish species, based on the catch per unit effort (CPUE), showed a distinct difference between the two seasons; 30 species were sampled in premonsoon, but 23 species were sampled in the monsoon, indicating a seasonal difference in the fish fauna. Tolerant species dominated the fish community (48.3%) in the stream, and the proportions prior to physical disturbance by the monsoon rain were evidently greater in the downstream reach than the upstream. This reflected the characteristics of urban stream polluted by nutrient enrichment as shown in the BOD and TP values. Sensitive species in the premonsoon decreased from the gradient of upstream-to-downstream reach. Such seasonal modifications in the trophic and tolerance guilds were evident. In the analysis of trophic guild and habitat guild, during the premonsoon the proportion of insectivore and riffle-benthic species were largely greater in the upstream reach than the downstream, whereas the proportions were opposite along the gradient of the stream in monsoon. Thus, the patterns of chemical water quality along the longitudinal gradients reflected the premonsoon conditions of insectivores and tolerant species, indicating that summer monsoon data of fish may not match with water quality due to large physical disturbance by flow regime. Seasonal monsoon in this region as well as the chemical pollution may act as a key role influencing the fish compositions of trophic and tolerance guilds and fauna. The data collected during the premonsoon rather than the monsoon, thus, may be better predictor for a diagnosis of stream health conditions.

• Journal of agricultural medicine and community health
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• v.21 no.1
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• pp.21-45
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• 1996

The purpose of this study is to compare the health status of Korean and Chosun-Jok elementary children. To accurately achieve the purpose, a survey was conducted in Yanbian area in China and Kojae in Korea during the period of June 15 to July in 1995. This survey was performed by using two survey methods. The first was the parents' survey method. It asked structured questions about their children. The second method focused on the actual health of the children. It used the collection of children's physical records in school. Guided by the school teachers, each child distributed the questionnaires to their parents. We used stratified-cluster sampling method to determine subjects. 1,083 questionnaires of 1,749 were used to analyze the data (666 questionnaires were incomplete and were not used in the analysis). Each questionnaire matched the data of their physical record. : Body Weight, Body Height, Chest-Circumstance, Eyesight, Dental Health. Using the data, we compared the BMI(Body Mass Index) the Koreans and Chosun-Jok in China. The results of this study were as follows : Comparing the general average physique of contained body height, body weight and chest circumstance of Korean and Chosun-Jok, the general physique of Chosun-Jok is inferior to that of Korean regardless of age and sex. Meanwhile, the average physical constitution of Korean compared the Chosun-Jok (i.e. eyesight and dental hygiene), revealed that the physical constitution of Chosun-Jok is superior to that of Korean without concern of age and sex. Average BMI of Chosun-Jok is lower than that of Koreans. But, it seemed that most of the students in both groups maintain an adequate health level. In the case of children from 10 to 12 years old, females are superior to males through all data contained of the body weight, the chest circumstance, and the body height. It seems that females and males have a different maximum growth age. Most of the parents preferred a good physique as a good health condition for their children. The physique of each child was affected with some variables, including the number of family members, and the educational level of the parents. According to the above results, the students' physique in Korea is superior to that of Chosun-Jok in China. But, Koreans are inferior to Ethnic Koreans in China in the students' physical constitution. In conclusion, we consider Chosun-Jok in China to maintain an adequate health level in their physique and physical constitution.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.8
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• pp.1-11
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• 1998

One of the desired features for the realizations of high quality Information and Telecommunication services in future is "the Sensation of Reality". This will be achieved only with the visual communication based on the 3- dimensional (3-D) moving images. The main difficulties in realizing 3-D moving image communication are that there is no developed data transmission technology for the hugh amount of data involved in 3-D images and no established technologies for 3-D image recording and displaying in real time. The currently known stereoscopic imaging technologies can only present depth, no moving parallax, so they are not effective in creating the sensation of the reality without taking eye glasses. The more effective 3-D imaging technologies for achieving the sensation of reality are those based on the multiview 3-D images which provides the object image changes as the eyes move to different directions. In this paper, a multiview 3-D imaging system composed of 8 CCD cameras in a case, a RGB(Red, Green, Blue) beam projector, and a holographic screen is introduced. In this system, the 8 view images are recorded by the 8 CCD cameras and the images are transmitted to the beam projector in sequence by a signal converter. This signal converter converts each camera signal into 3 different color signals, i.e., RGB signals, combines each color signal from the 8 cameras into a serial signal train by multiplexing and drives the corresponding color channel of the beam projector to 480Hz frame rate. The beam projector projects images to the holographic screen through a LCD shutter. The LCD shutter consists of 8 LCD strips. The image of each LCD strip, created by the holographic screen, forms as sub-viewing zone. Since the ON period and sequence of the LCD strips are synchronized with those of the camera image sampling adn the beam projector image projection, the multiview 3-D moving images are viewed at the viewing zone.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.7
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• pp.61-69
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• 2010

In this paper, an 1.2V 8b 800MSPS A/D Converter(ADC) with an odd number of folding block to overcome the asymmetrical boundary-condition error is described. The architecture of the proposed ADC is based on a cascaded folding architecture using resistive interpolation technique for low power consumption and high input frequency. The ADC employs a novel odd folding block to improve the distortion of signal linearity and to reduce the offset errors. In the digital block, furthermore, we use a ROM encoder to convert a none-$2^n$-period code into the binary code. The chip has been fabricated with an $0.13{\mu}m$ 1P6M CMOS technology. The effective chip area is $870{\mu}m\times980{\mu}m$. SNDR is 44.84dB (ENOB 7.15bit) and SFDR is 52.17dBc, when the input frequency is 10MHz at sampling frequency of 800MHz.

• Journal of Sericultural and Entomological Science
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• v.2
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• pp.73-81
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• 1962

This treatise is to analyze the chemical components in the mulberry varieties which are cultured in Korea and to estimate the nutritive values for them. Some of these varieties were developed lately in this country just by the general breeding aspect of mulberry leaf producing and silkworm raising experimentation without analysing the nutritive values of them which may be differed by various culturing condition. This work will be helpful for the improvement of mulberry varieties and the correct judgement of them. The varieties used for the analysis are as followings; A. Morus bombycis Koridz species. 1.Ichi-Hei. 2. Shimano-Uchi B. Morus alba L. species. 3. Kairyo-Nezumigaeshi. 4. Suwon-Daeyop. 5. Suwon No. 3. 6. Suwon No. 4. 7. Yongchon-Chuwoo. C. Morus Ihou (Ser.) Koidz species. 8. Ro-Soh. The specimens were eventually taken under the air and soil dry season because of the rain shortage during the sampling period and the results are found as a rather different from the normal specimen under the normal climate. Therefore, this treatise will be an important report on a special culturing condition and the nutritive values by the mulberry varieties, and still comparable because they were grown under the same condition. The individual conclusions are; 1. Yongchon-Chuwoo which was originated in this country, was found as an important variety for this country from the aspect of mulberry nutritive value and leaf producing amount, and it is believed that this is the best suitable variety for the soil of Korea. 2. Ichi-Hei occupies the better situation as well as Yongchon-Chuwoo from the nutritive criticizing even though it was originated in Japan. 3. The lately developed Suwon No.3 and No.4 are best from the leaf producing point of view, but they are not found such a good varieties from the nutritive aspect. The result may be happened as poor because they were cut before spring sprout started. 4. Ro-Soh which was normally recognized as a poor variety, was also found as a poor nutritive and leaf producing variety. 5. The crude protein and crude fat components in the mulberry leaves decreased as the leaf maturity was progressed, but the crude fiber and crude ash components increased reversively in general view. It was also found that there were some specific changing nature by the mulberry varieties and could not rule them by just one conclusion. 6. During the air and soil dry season, the ash component increases but the hydrocarbon and moisture contents decrease considerably, and which resulted to the increase of mulberry hardness ratio and the decrease of sugar-protein ratio, eventually it causes the decrease of the nutritive value. It was also found that Ichi-Hei, Ro-Soh, and Suwon No. 3 had a strong recovering nature to their normal nutritive condition after raining. 7. Mulberry is of course a rich calorie diet, and is calculated as 50 to 60 Cal. per gram.

• Journal of Food Hygiene and Safety
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• v.26 no.2
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• pp.154-159
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• 2011

Inadequate food handling and poor hand hygiene playa major role in the occurrence of foodborne diseases. The objective of this study was to find out if the level of microbial contamination on the hands of food preparers varies by time during their working period. This study focused on the contamination of aerobic plate count, total and fecal coliforms, Escherichia coli, Staphylococcus aureus, and Salmonella spp. Sampling from left hand and right hand of twenty food preparers was done with glove-juice method at every two hours during their work. Microbiological testing was conducted according to the Food Code of Korea. The microbiological load on the hands was changed over time. Samples taken from their hands before work and at 8 hours showed higher levels of bacteria than those taken at 2, 4, and 6 hours during work and/or after work (p < 0.05). The contamination levels of microorganisms were consistently higher in right hand than in left hand. Poor hand hygiene practices were indicated by the positive results for total and fecal coli forms, E. coli, S. aureus, and Salmonella spp. on the hands of some food preparers. This study indicates food preparers' hands can be a vehicle of pathogen during their work. The results of this study emphasize the importance of hand hygiene education and training targeting the food preparers.

• Journal of Korean Public Health Nursing
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• v.16 no.2
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• pp.239-253
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• 2002

Health care for women regularly focuses on the reproductive system to the exclusion of other health needs. The lack of research focusing on women's common health issues is a major problem to the enhanced optimal level of women's health. Health care providers have to recognize biological and social differences between men and women. This study was conducted to identify the baseline data and their correlation of health perception, health behavior, and health status of adult women for developing nursing intervention. The study was a descriptive correlational design. A convenient sampling method was used for collecting data from 103 adult women, over 18 years of age, during the period from Sep 1 to Nov 30, 2001. The study's subjects were interviewed using a structured questionnaire. The instruments for this study were the health perception scale modified by Lee(1985) based on the tool developed by Ware(1977) and Jenkins (1966), and the health behavior scale by Ko, Kumja(1987). Health status was measured by the short form Cornell Medical Index(CMI) modified by Nam, Hochang(1965). The data were analyzed SPSS PC+, by frequency, mean, t-test, ANOVA, and Pearson correlation coefficients. Also, the Duncan test was utilized for a post hoc test of ANOVA. The results of this study are as follows: 1. The mean score for health perception was 3.02(S.D=0.39) on a 5 point scale. 2. The mean score for health behavior was 3.08(S.D=0.43) on a 5 point scale. 3. The mean score for health status was 18.54 on 58 items. The mean score for physical symptoms of a subscale of health status was 11.30 on 36 items and the mean score for psychological symptoms was 7.37 on 22 items. 4. The relationship of sociodemographic variables to health perception. health behavior, and health status of women.: 1) There were significant differences in the scores of health perception by disease experience(t=-3.37, p=0.00). 2) There were significant differences in the scores of health behavior by age(F=10.52, p=0.00), height(F=4.73, p=0.01), marital status(t=-5.56, p=0.00), educational background(t=2.90, p=0.00), and drinking or non-drinking(t=2.17, p=0.03). 3) There were significant differences in the scores of health status by educational background(t=2.28, p=0.02) and disease experience(t=2.61, p=0.01). 5. Health perception showed significant positive correlation with health behavior(r=0.39, p=0.00). Health perception showed significant negative correlation with health status(r=-0.44, p=0.00), that is, the more women perceived health, the less she complained about unhealthy symptoms. Health behavior had no significant correlation with health status but showed a positive correlation with psychological symptoms of a subscale of health status(r=-0.19, p=0.05). Many of the leading causes of disease are preventable through changes in health perception and behavior. The need to increase individual awareness of relationships among health perception, health behavior, and health status and to enhance knowledge regarding the long-term effects of positive health behaviors, is an important nursing strategy for women's health promotion.

• Journal of Korean Public Health Nursing
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• v.10 no.1
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• pp.12-22
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• 1996

Currently. exchanges of industrial workers between countries are more active than ever. and the problem of AIDS in connection with the operation of preventive educational programs has reached a point where the issue cannot be limited to native people alone any more. Based on such judgement. this research has been carried out to provide basic study materials by grasping the latent factors representing the difference between countries in the levels of right knowledge. attitude and behavior with respect to AIDS maintained by workers who have grown in different social and cultural living background. During the period from Apr. 1. 1995 to Jun. 30. questionnaires. written both in Korean and English, were distributed to Korean and Malaysian employees working at certain Korean video manufacturers. and the results of replies. given by 80 workers who were analyzed through matched sampling· method where ages and sex matched by country. were used as the research materials. The gathered materials were analyzed through the SPSS package t-test. ANOVA. factor analysis and multiple stepwise regression methods. and the following results were obtained. 1. The 2 extracted latent factors could be named 'common. social' knowledge factor and 'in-depth. psychological' knowledge factor respectively. 2. The percentile points of 'external. social' knowledge factor. in the case of Korean workers. howed 90.0 at average. a figure 13.75 points higher than those of Malaysian workers. 76.25. On the other hand. the percentile points of the 'in-depth. psychological'knowledge factor showed 70.80 at average in the case of Korean workers. a figure 7.47 points lower than those of Malaysian workers. 78.33. Meanwhile. the difference in percentile points between the 2 latent factors was 8.54 at average. indicating that the points of 'in-depth. psychological' knowledge factor was lower than those of the 'external. social' knowledge factor. 3. As for Korean workers. the percentile points of the 'in-depth. psychological' knowledge factor showed higher points in office workers than in non-office workers. and such variables exhibited in the position of workers can explain the $7\%$ of the latent factor. The percentile points of the 'in-depth. psychological' knowledge factors. in the case of Malaysian workers. showed higher points in groups who had religion than in groups who did not. and higher points in groups who obtained information from newspapers than in groups who obtained from televisions or other sources; and with these 2 variables. $26\%$ of this latent factor can be explained. The results. of analysis described so far suggest that while Korean workers possessed general level of knowledge on AIDS. they had low level of practical knowledge as far as its depth is concerned. and that they had social prejudice on patients as well as on the AIDS infection route. In addition. because the overall knowledge level of Malaysian workers. is lower than that of Korean workers. it suggests that separate programs intended for Malaysian workers are required prior to executing integrated programs.