• Clinical and Experimental Reproductive Medicine
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• v.36 no.4
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• pp.311-319
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• 2009

Objective: Human embryonic stem cells (hESCs) have the capacity to differentiate into all of the cell types and therefore hold promise for cell therapeutic applications. In order to utilize this important potential of hESCs, enhancement of currently used technologies for handling and manipulating the cells is required. The cryopreservation of hESC colonies was successfully performed using the vitrification and slow freezing-rapid thawing method. However, most of the hESC colonies were showed extremely spontaneous differentiation after freezing and thawing. In this study, we were performed to rapidly collect of early passage hESCs, which was thawed and had high rate of spontaneously differentiation of SNUhES11 cell line. Methods: Four days after plating, partially spontaneously differentiated parts of hESC colony were cut off using finely drawn-out dissecting pipette, which is mechanical separation method. Results: After separating of spontaneously differentiated cells, we observed that removed parts were recovered by undifferentiated cells. Furthermore, mechanical separation method was more efficient for hESCs expansion after thawing when we repeated this method. The recovery rate after removing differentiated parts of hESC colonies were 55.0%, 74.5%, and 71.1% when we have applied this method to three passages. Conclusion: Mechanical separation method is highly effective for rapidly collecting and large volumes of undifferentiated cells after thawing of cryopreserved early passage hESCs.

• Clean Technology
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• v.21 no.1
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• pp.76-82
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• 2015

Volatile organic compounds (VOC) free adhesives have been interested by many scientists and engineers due to environmental regulations and the safety of industrial workers. In this work, a series of composites composed with bisphenol A epoxy resin used as solvent, dicyandiamide, and promoter were prepared to investigate the most appropriate molar ratio for steel-steel adhesion. The cured test specimen of each composite were measured with universal testing machine (UTM) to figure out mechanical properties such as tensile strength, Young’s modulus, and elongation. Furthermore, the lap shear strength of the specimen was tested with UTM while impact resistance was measured with Izod impact tester. The composite whose molar ratio of epoxy resin to curing agent is 1 : 0.9 (sample 3), showed better tensile strength, coefficient of elastic modulus, elongation, and impact strength than other composites did. The highest tanδ from dynamic mechanical analysis (DMA) was observed from sample 2 (epoxy resin: dicy = 1 : 0.7) while sample 3 showed slightly lower tanδ than that of 2. The morphology of the fracture surface of the cured composites from SEM showed that the number of subtle lines on the surface caused by impact increase as the contents of amine curing agent accrete. Furthermore, the viscosity change of sample 5 (epoxy resin: dicy = 1 : 1.3) was observed to confirm its storage stability.

• Journal of the Korean Society of International Agriculture
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• v.30 no.4
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• pp.370-375
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• 2018

In order to promote the mechanized cultivation of perilla for seed, which has been increasing in cultivation area and production recently as demand increases according to the health-functional effects, we carried out this experiment to determine the optimum sowing time of perilla to minimize the seed loss at harvest and increase the yield. We used two different types of perilla varieties, 'Sodam(small-branch)' and 'Deulsaem(multi-branch)', and the sowing time was June 15, June 30, July 15 and August 1. As the sowing time is late, days of growth from sowing to flowering were shortened, and they were shortened from 14, 26 and 31~32 days on June 30, July 15 and August 1 as compared with June 15, respectively. And, the stem length and culm diameter were shortened or tapered and the number of nodes tended to decrease. The number of effective branch was 82%, 61% and 56% on June 30, July 15 and August 1 as compared with June 15, respectively. Accordingly, it seems to make against in securing the yield from July 15. And, the lowest cluster height was generally shorter as the sowing time is late, and the height was below 15cm on July 15 and August 1. It seems that this may work against the machine harvest. There was a high degree of significance between the sowing time and the yield. Although, the total yield was not statistically significant among June 15, June 30 and July 15, the ratio of shattering seed at harvest was in order of July 15, August 1(30.3%)> June 15(15.3%)> June 30(13.5%). Therefore, the net yield except for shattered seed was higher in order of June 30${\geq}$ June 15> July 15> August 1. This tendency was characteristic regardless of variety and sowing method. And, the protein content in perilla seed increased as the sowing time was delayed, and the content was the highest on August 1. The content of crude fat was relatively high on June 15 and July 15 in 'Sodam', and June 30 and July 15 in 'Deulsaem', respectively. And, the content of linolenic acid was found to be the highest on August 1. As a result, the optimal sowing time for machine harvest of perilla for seed is about June 30. At this time, it is determined that the sowing time is the most suitable to be advantageous in increasing the yield of perilla seed, while minimizing the seed loss due to the shattering at harvest.

• Journal of the Speleological Society of Korea
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• no.63
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• pp.1-8
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• 2004

The non-magnetic materials with non-conductive showing high structure dispersity were developed on the base of natural quartz and lava-scoria which was collected from Je-ju island in Korea, and treated by methane-chemical technology those were obtained novel properties of magnetization through the analyzing. Depending on the processing conditions and subsequent applications the materials produced by strong methane-chemical reaction (MCR) in alcohol solution showed concurrently magnetic, dielectric and electrical properties. The obtained magnetic-electrical powders classified by aggregate complex of their features as segnetomagnetics, containing a dielectric material as a carrying nucleus, particularly the quartz on that surface one or more layers of different compounds were synthesized having thickness up to 10～50 nm and showing magnetic, electrical and other properties. It was confirmed in magnetizing process that powders of quartz and lava-scoria produced by MCR were better oil adsorbent as of oleophilic and floating matter on water surface although their specific gravities are comparably more than 1 in quartz or less than unity, as that of water, in lava-scoira. Therefore, it will be Possible and very useful to remove low density and light gravity oil spillage in difficult recovery from sea and inland water contamination spread on water surface, by marine accident and ship sinking accident occurring frequently in recent years, by way of magnetic adsorbent conveyer system in continuous, if it could be built up the mass Production system of water-floating magnetizable oleophilic adsorbent materials with use of iow cost and good Qualify lava-scoria spread on volcano district in Je-ju island. And, there will also be urgent advent of necessity with strong possibility to develop useful applications of various magnetic functional materials include oleophilic adsorbent for removal of sea oil-contaminants and maritime pollutants, and other kinds of various utilities in industrial applications and practical uses of novel functional materials in the fields of environments and health care applications with in deep expectation.

• Tuberculosis and Respiratory Diseases
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• v.45 no.3
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• pp.536-545
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• 1998

Background: The studies on prediction equations of pulmonary function parameters for adults in Korea have been performed in a reference population mainly consisted of young and middle ages. So they included a relatively few elderly who conducted pulmonary function test frequently in clinic. We established prediction equations of pulmonary function parameters for healthy adults over 50 years old in rural area and compared this results with those of other studies. Therefore we attempted to consider normative values of pulmonary function tests for elderly in Korea. Method: Five hundred thirty-three women and men over 50 years old in rural area were participated. A "healthy" subgroup of 110 women and 32 men were identified by excluding those who had conditions that negatively influenced pulmonary function. We derived prediction equations for FVC, $FEV_1$ and $FEV_1%$ by multiple linear regression method from their age, heights and weights in each sex. Results: Prediction equations for FVC and $FEV_1$ in each sex were derived as follows Male; FVC (L)=0.02488Height(cm)-0.0269Age(years)+0.493 $FEV_1(L)$=0.01874Weight(kg)-0.0282Age(years)+2.906 Female; FVC(L)=0.02160Height(cm)-0.0192Age(years)-0.0125 $FEV_1(L)$=0.01720Height(cm)-0.0194Age(years)+0.3890 Prediction equations for $FEV_1%$ were not derived because $FEV_1%$ didn't have statistically significant terms. Comparing Predicted values that were calculated by substitution into the equations of various studies of mean values of age, heights and weights from this study, FVC and $FEV_1$ values in men of this study were lower than those of other studies. In women, FVC and $FEV_1$ values of this study were as similar as or lower than those of the study conducted for healthy elderly blacks in U.S.A respectively. Conclusion: We have got prediction equations of pulmonary function parameters which were driven from forced expiratory spirogram in adults over 50 years old in rural area. Predicted values of this study were lower than those of other studies which were conducted in Korea. So we consider that the study for spirometry reference values for elderly Korean using the method compatible with ATS recommendation need to be conducted more frequently forward.

• Journal of Family Resource Management and Policy Review
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• v.25 no.1
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• pp.91-112
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• 2021

This study aimed to explore the influence of family characteristics on the work-life balance of early adolescents. A series of data analyses was conducted on adolescents' use of time in daily life on the basis of 2018 Korean Children and Youth Panel Survey (KCYPS 2018). We found that the work-life balance of youth is related to their parents' health status, presence of older siblings, household income, parenting attitude, parent-child communication time, and mother's occupation. The work-life balance of the fifth graders is more likely to be influenced by family characteristics compared with that of the eighth graders. In particular, the fifth graders' sleep deprivation is affected by the mother's occupation, but there is no significant effect on the eighth graders' sleep deprivation. An important factor in skipping breakfast is household income, with adolescents from low-income families tending to skip breakfast more than five days a week. In addition, parents' health status and parenting attitude are significantly related to skipping of breakfast in early adolescents. Household income is related to the after-school private tutoring hours of both the fifth and eighth graders; however, parenting attitude and mother's occupation are also significant influencing factors of the fifth graders' after-school study. Mother's occupation is related to excessive cell phone use; specifically, the fifth graders whose mothers work white-collar jobs, sales and services or manufacturing are more likely to play with cell phones more than three hours a day than those whose mothers are full-time housewives. These results suggest that the work-life balance policies targeted at the family characteristics of adolescents can improve family environments in a manner that enhances adolescents' life balance, thus supporting the well-being of early adolescents and their families.

• The Korean Journal of Archival Studies
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• no.35
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• pp.161-206
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• 2013

'Maeul' is a concept connoting a community. As a place where ordinary people's lives are planned and realized, Maeul is the foundation of their daily lives as well as a place where they work, rest and enjoy pastime activities. In Korea, however, most Maeul communities are dismantled while going though the modern period representing colonization and developmental dictatorship. Growth-oriented industrialization and urbanization turned into such adverse effects as individualization, a sense of loss and a sense of alienation. Recently, through innovations from below, Maeuls are restored, and through Maeul communities restored this way, every Maeul and many researchers carry out activities to build a healthy civil society. This study was conducted on such a background. For a healthy restoration of Maeul communities and a sustainable operation of those communities, it is necessary to establish archives where record the trace of Maeul members' daily lives and relations between those members. The archive of Maeul communities is a place that contains each Maeul's local characteristics as well as human relations as well. It is because this place can be space where Maeul members can record their history, communicate with each other and make a better future. The archive of Maeul communities can be made into various different models, which can be operated by reflecting the identity of a community such as main agents and characteristics, objectives and orientation of objects recorded. Rather than when Maeul communities exist as individuals, they can display more important functions and better effect when they form a network. Therefore, it is needed to provide various and creative methodologies different from the existing government-led record management. Not only on the form of archives, but also all over their functions, such as collection, arrangement, classification, evaluation, management and utilization, Maeul and Maeul residents' norms, orientation and realistic conditions should be thoroughly reflected. Starting from a chance to look back at individuals' lives, the archive of Maeul communities will be a new chapter to restore and build a healthy community in our society and overcome social contradictions from below. Moreover, the archive of Maeul communities has a great significance that it will broaden its prospect creatively with a new paradigm, not only mechanically turning the existing public sector-centered record management into a non-governmental sector.

• Journal of agricultural medicine and community health
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• v.24 no.1
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• pp.13-33
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• 1999

The aim of this study was to investigate fatigue scores, physical complaints, farmer's syndrome and to find out its risk factors among farmers. The questionnaire survey was conducted to 177 vinyl house workers and 213 farmers who lived in Chongyang gun of Chungnam province from February 24 to March 15, 1998. The obtained main results were followings; 1. The fatigue scores were not significantly different between vinyl house workers and farmers. The fatigue scores were higher in female group, lower education group, shorter sleep hours group(under 8 hours), nonsmoker, nondrinker group than otherwise groups. There was not statistically significant difference between the mean fatigue scores and age, eating habit and body mass index. Duration of farming years in vinyl house and farming area and number of farming workers in farmers family showed a slight relationship with the fatigue score. 2. Health scores were not different between vinyl house workers and farmers. The health states was poorer in female group, lower education group, shorter sleep hours group(under 8 hours), nonsmoker group, and nondrinker group than otherwise groups by health scores. Health scores were not related with age, eating habit and body mass index. 3. The proportion of farmer's syndrome was 49.1% in vinyl house workers and 52.1% in farmers. That was higher in female than in male and the higher proportion was found in the lower education group of vinyl house workers and farmers. The proportion of farmer's syndrome was higher in the group of smoker, alcohol drinkers and over or under weight in vinyl house workers, but did not differ in those of farmers. 4. By multiple logistic regression, sex and sleep hours were risk factors affecting to farmer's syndrome. Odds ration for female group was 2.53 (reference group was male) and that for over 8 sleep hours group was 0.74 (reference group was under 8 sleep hours group). 5. The chief complaints by CMI were "I am difficult to work due to aching the back and the limbs", "I feel prickle pain in the limbs", "I sometimes have a twinge in the limbs", "I am not quite well as having a pain in the limbs", "I feel weaker grasping power than before" in both of vinyl house workers and farmers. Vinyl house workers more frequently pointed out skin darkening, skin disease and hemorrhoids than farmers. 6. According to correspondence analysis, skin disease of vinyl house workers was related to vinyl house farmers and digestive and general symptom was associated with male and endocrinological and muscular symptom was associated with female in vinyl house workers. And it revealed that farmer's syndrome was highly related with female and farmers relatively. By the above results, the fatigue scores, perceive health and farmer's syndrome did not much differ in two groups, but aged female farmers should be considered as female farmers represented higher fatigue score, farmers syndrome and poorer perceive health than male farmers in addition to farmer's syndrome was increased with ageing process. Also feeble but distinguished symptoms which might be due to working environment were observed especially in vinyl house workers and that should be considered and investigated continuously.

• Journal of agricultural medicine and community health
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• v.25 no.1
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• pp.29-49
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• 2000

Objectives: To estimate the prevalence rate of hypertension, the changes of health behavior, and compliance for the drug treatment after diagnosed as hypertension. Methods: 7,030 persons who live in Cheonan City of Chungnam Province were selected by the cluster sampling method, and 5,372 persons were surveyed by questionnaire and health examination. This data is analyzed by Chi-square test on each variable. Results: 49.8%- of men and 38.8%- of women had been diagnosed as hypertension, and the prevalence rate of hypertension was significantly increased with aging in both gender. The prevalence rate tended to decrease in highly educated women group. Unemployed persons or obese persons showed relatively higher prevalence rate. The prevalence rate of hypertension increased in groups with higher total cholesterol levels over 240 mg/dl, and groups with glucose level over 200 mg/dl. 53.1%- of male patients and 66.6%- of female patients showed compliance for antihypertensive treatment. Compliance for treatment was higher in aged group or lower educated group in both gender. Among men, proportion of compliant subjects was higher in unemployed group(49.3%-), and lower in labor or primary industry than the others but among women, there was not any significant difference. And men with compliance for treatment had higher monthly income than the others, but women did not show any. Conclusion : This population had a high prevalence rate of hypertension which may lead to cardiovascular disease. Therefore health education programs and distribution of information must be emphasized in order to increase compliance to treatment and encourage the change of health behavior to promote health.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.224-239
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• 1994

In this study we examined several subjective symptoms in an exposed group and an unexposed group to perchloroethylene. The exposed group consists to 30 workers employed in 23 dry-cleaning establishments located in Chung Cheung Do, whereas the unexposed group consists of 42 officers employed in a certain university. This study was conducted from October, 1993 to March, 1994. Also we investigated personal exposure levels and area concentration of PCE, and performed hematological and biochemical examination in blood and urine samples from the exposed group. The results are : 1. The exposed group highly complains several subjective symptoms, particularly in neuropsychiatry, eye, respiratory system and digestive system, compared with the unexposed group. But complaint rates in the exposed group are not related with PCE exposure levels. 2. PCE exposure levels for all dry-cleaning establishment varied widely, from 0.18 to 37.58ppm. The mean exposure level for centers of chain was 16.85ppm, and for local laundries was 8.83ppm, while for self-service establishment it was 3.07ppm. Eighty three percent of the workers were exposed less than the half-level(25.0ppm) of the Korea 50.0ppm standard for eight-hour PCE exposure. Seventeen percent of them exceeded the half-level of the Korea TLV. 3. Statistical correlation exists between the work load(number of operation cycles of equipment and the mass of processed textiles) and the personal exposure levels to be observed. 4. In hematological examination the values of WBC, RBC, Hgb, Hct, MCV, MCH, MCHC and PLT in the exposed group were within normal ranges. In biochemical examination(GOT, GPT, ALP, U-A and LDH) most of the items were within normal ranges. From this surveys conducted on 23 dry-cleaning establishments, the complaint rates of the exposed group to PCE in several subjective symptoms were higher than those of the unexposed group, and PCE exposure levels in all dry-cleaning establishment were below the Koera standard 50.0ppm. In hematological and biochemical examination the significant abnormalities by occupational exposure to PCE were not observed. However, the workers employed in dry-cleaning establishments are always faced with risk, becauses they are also exposed to several organic solvents used to remove stains. Therefore, various measures to improve occupational environment in dry-cleaning establishment should be considered.