• Korean Journal of Veterinary Research
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• v.31 no.4
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• pp.355-365
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• 1991

This study was conducted in order to observe the changes in cellular association of seminiferous tubules from 16 to 24 weeks of age and to obtain the cycle and relative duration of the seminiferous epithelia from 28 to 44 weeks of age in Korean native dogs. The results were summarized as follows; 1. Gonocytes were seen at 16 weeks of age, however they were not observed as from 20 weeks of age. Both type A and type B-spermatogonia occurred from 20 weeks, while primary spermatocytes were found from 20 weeks. Secondary spermatocytes and spermatids appeared from 28 weeks. Spermatozoa were observed at first at 28 weeks of age. 2. Type A-spermatogonia appeared approximately 1.6 times as many at stage II compared to stage I, while the same numbers of cells were seen in both stage I and VII, showing the least number among VIII stages of the cycle of the seminiferous epithelia. The type B-spermatogonia were found from stage VI to VIII, Leptotene phase of the primary spermatocyte divided from type B-spermatogonia in stage VII observed at the stage VIII. Pachytene phase of the primary spermatocytes were shown the least in number at stage IV. The secondary spermatocyte could be seen only at stage IV. 3. The relative frequency of each stage from stage I to VIII of the cycle of the seminiferous epithelia was 30.3, 12.0, 9.8, 4.2, 8.5, 10.5, 11.4 and 13.4% respectively. Thus the establishment of spermatogenesis in Korean native dog was completed from 28 weeks of age.

• Journal of the Korean housing association
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• v.1 no.1
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• pp.37-48
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• 1990

The objective of this study is to suggest a housing life cycle of Korean families which adds to the establishment of reasonable housing standards and to the prediction of fufure-oriented family housing behavior by reviewing published papers. Following model is suggested as a housing life cycle suitable to assess the family housing behavior in Korea. 1st stage : period of house searching 2nd stage : period of house changing 3rd stage : period of house stabilizing \circled1 size enlargement phase \circled2 quality improvement phase \circled3 stable settlement phase 4th siage : period of house contracting 5th stage : period of house depending Since the proposed model is hypothetical, it must be tested and modified by the extensive social survey research on the real housing event history.

• Journal of Families and Better Life
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• v.2 no.1
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• pp.35-55
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• 1984

This study aims to present basic data for a reasonable home management through investigating the change of home economy conditions incidental to the family life cycle, also through analyzing the effect of socio-anthropological variables on the family-life cycle. The data investigation using the questionnaires method was conducted on housewives in Seoul as the central census tract. Housewives as the subject of investigation were chosen by the method of the purpose-sampling in consideration of the regional differences and the socio-economical strata. Nine hundred and forty questionnaires were distributed to housewives but seven hundred questionnaires were collected. Only five hundred and ten questionnaires of them were analyzed in this study. The frequency and the percentage of collected data, first of all, were founded in order to grasp the general characteristics of the subject of investigation. To classify the stage of family life cycle, the correlations of the classifying factors among each group were examined x2 Test and One-Way ANOVA were applied to explore the differences among each stage of the change of household-economy. And the effect of socio-anthropological variables on the change of household- economy was analyzed by Two-way ANOVA. the conclusions derived from the results of this study are as follows; 1) The marriage-period and the educational conditions of the first child were selected as the classifying factors through analyzing correlation among the age, the marriage-period and the educational conditions of their children. As a result of this analysis, the family life cycle were classified into seven stages: Stage 1; Establishment Stage 2; Preschool family Stage 3; Elementary school family stage 6; Adult period family Stage7; Marriage period family . 2) The change of household economy incidental to the progress of family life cycle has a significant differences in all of variables (except the other member of family's income) Stage 1; Though the husband's income and the income from property are on a low level, the total income is on a high level due to the housewife's income. Stage 2; The total income is on a low level owing to the decrease of house wife's income, though the husband's income keep growing. Stage 3; Owing to the increase of husband's income, the cost of living as well as the total income keeps growing but the savings are on the decrease. Stage 4; Compared with Stage 3, the total income tends to be on a low level but the living expenses are on the increase. Stage 5; The husband's income is on the highest level in the stages of family life cycle. The total income and the living expenses are on a high level. Stage 6; The income of husband and housewife are on the remarkable decrease but the children's income is on the increase. Stage 7; Owing to the increase of the children's income and the income from property, the total income is on the highest level in the stages of family life cycle. 3) Considering the effect of socio-anthropological variables on the conditions of household-economy, family system has an significant effect on children's income. the husband's occupation exerts a significant effect upon the housewife's and children's income. The husband's schooling exercises an effect upon the children's income. S.E.S has a important effect on the income of husband, housewife and children. From the above results, it is found that the change of household-economy conditions is incidental to the progress of family life cycle. Therefore, a suitable measure to cope with the desire of family and the conditions of household-economy should be prepared, in order to carry on a reasonable home management.

• Biomedical Science Letters
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• v.13 no.1
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• pp.61-69
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• 2007

The cycle of the seminiferous epithelium and the development of spermatids of Apodemus agrarius coreae were observed using a light microscope. The cycle of the seminiferous epithelium was divided into 10 stages, and developing spermatids were subdivided into 10 steps. The Golgi phases occurs the first two steps ($St_1,\;St_2$), and the cap phases had the next two consecutive steps ($St_3$ and $St_4$). The acrosomal phases consisted of steps $5{\sim}8$ ($St_5-St_8$), and the remaining two steps consisted the maturation ($St_9$) and spermiation ($St_{10}$) phases, respectively. Type Ad spetmatogonia are appeared in all stages (I-X). Type Ap spermatogonia appeared from stage I and II, In spermatogonia from stage III, IV and V, and B spermatogonia from stages VI. The leptotene spermatocytes appeared from stage VII, zygotene from stages I, II, VIII, IX and X, pachytene from stage III to VIII, diplotene in stage IX, and meiotic figures and secondary spermatocytes in stage X. These data are considered in relation to interspecific differences in sperm morphology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.1013-1019
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• 2011

In this paper, simulation works for a multi-stage cascade refrigeration cycle using propane, ethylene and methane as refrigerants have been performed for the liquefaction of natural gas using Peng-Robinson equation of state built-in PRO/II with PROVISION release 8.3. The natural gas feed compositions were supplied from Korea Gas Corporation and the flow rate was assumed to be 5.0 million tons per annual. Supply temperature for propane refrigerant was fixed as $-40^{\circ}C$, that for ethylene refrigerant as $-95^{\circ}C$, and that for methane refrigerant as $-155^{\circ}C$. For the multi-stage refrigeration cycle, three-stage refrigeration was assumed for propane refrigeration cycle, two-stage refrigeration for ethylene refrigeration cycle and three-stage refrigeration for methane refrigeration cycle. Natural gas was finally cooled and liquefied to $-162^{\circ}C$ by Joule-Thomson expansion. Conclusively, 91.71% by mole of the natural gas liquefaction ratio was obtained through a cascade refrigeration cycle and Joule-Thomson expansion and 0.433 kW of compression power was consumed for the liquefaction of 1.0 kg/hr of natural gas.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.6
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• pp.782-791
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• 1998

This paper presents a computer simulation of five types of triple effect absorption cycles employ-ing the refrigerant absorbent combinations of NH3/LiNO3 low-pressure type NH3/LiNO3+H2O/LiBr binary two-stage type series flow cycle and two types of parallel flow cycle for H2O/LiBr. The absorption systems is investigated through cycle simulation to obtain the system characteristics with the cooling water inlet temperature approach temperature of absorber loss temperature of absorber and chilled water outlet temperature. The most important characteristic temperature of absorber and chilled water outlet temperature. The most important characteristic of NH3/LiNO3 low-pressure type and a NH3/LINO3+H2O/LiBr binary two-stage type is that it obtains a coefficient of performance higher than the sum of the performance coefficients of its part operating independently. As a result of this analysis the optimum designs and operating conditions were determined based on the operating conditions and the coefficient of performance.

• Journal of Korean Academy of Nursing
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• v.50 no.1
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• pp.147-157
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• 2020

Purpose: This descriptive study aimed to identify the menstrual cycle characteristics and premenstrual syndrome (PMS) prevalence in Korean young adult women using the retrospective and prospective Daily Record of Severity of Problems (DRSP). Methods: In the first stage, participants included 151 nursing students studying in a university located in Seoul. Data were collected from April 20 to June 2, 2017, using the questionnaire on menstrual characteristics, pictorial blood assessment chart, and retrospective DRSP. In the second stage, participants included 17 students with PMS, based on the screening conducted in the first stage. Data were collected using the prospective DRSP from May 29 to 2 September 2, 2017. Results: Of the study sample, 104 participants (68.9%) had regular periods. Those with regular periods had 11.97 periods annually with a menstrual cycle of 29.38 days and a period duration of 5.72 days. Fifty-five participants (37.4%) showed menorrhagia. Sixty-four participants (42.4%) were found to have PMS based on their retrospective DRSP. When the ratio of women (52.9%) with PMS shown in the prospective DRSP was used as a positive predictive value, the estimated PMS prevalence was 22.4%. Conclusion: This study provides clinically significant PMS prevalence among Korean young adult women, positive predictive value of the retrospective DRSP, and valid data to basically understand the menstrual cycle characteristics experienced by these women.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.9
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• pp.931-937
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• 2012

In this study, we assessed environmental impacts of compound humidifiers using environmental life cycle assessment and presented the ways to improvements in energy consumption of them. We found eco-design parameters and $CO_2$-eq emissions in each stage of raw material acquisition, manufacturing, transportation, use and disuse in life cycle of the compound humidifiers. The highest $CO_2$ emission is found to be in the stage of use among all stages of life cycle, which is mainly due to power consumption in thermal heating of heating coil for sterilization during humidification. The power consumption and $CO_2$ emission in the stage of use can be reduced to 1/4 and 1/3 at the highest estimate through improvement of sterilization method, respectively. We suggested the replacement of conventional thermal heating coil by ultra violet light-emitting diodes (UV-LED) for sterilization and then presented the experimental results on the sterilization effects of UV-LEDs.

• Korean Journal of Veterinary Research
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• v.39 no.3
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• pp.455-462
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• 1999

This study was designed to investigate the number of the growing and mature follicles in each stage of estrus cycle in mature rats. Eighteen mature rats(Sprague-Dawley, initially 190~230gm) were randomly alloted into 4 groups(proestrus, estrus, metestrus, and diestrus) according to estrus cycles. The uteri and ovaries of rats were collected and then alternative sections of paraffin embedding ovaries were stained with H-E. Numbers of large, middle and small follicles or only large and middle follicles from secondary and tertiary follicles were investigated by LM photography of preparations. Small follicles were defined as secondary follicles with 2~5 cell layers of granulosa cells surrounding the oocyte, and middle follicles were defined as secondary follicles with more than 5 cell layers or with early signs of antral cavity or with more than one small cleft on either side of the oocytes and large follicles were defined as tertiary follicles with a single medium or large antral cavity. The number of follicles in a pair ovary per rat was appeared to be ranged from 207 to 370 and the mean number of these follicles was $270.4{\pm}52.6$ and the mean number of follicles per ovary was $134.9{\pm}32.0$. The mean number of large, middle and small follicles per ovary was appeared to be $16.4{\pm}4.4$($12.2{\pm}3.3%$), $36.2{\pm}8.6$($26.8{\pm}6.4%$), and $82.7{\pm}24.0$($61.3{\pm}17.8%$), respectively. The mean number of large and middle follicles in each stage group of estrus cycle was appeared to be $17.8{\pm}2.1$ and $38.3{\pm}7.4$ at proestrus stage group, $15.7{\pm}5.2$ and $38.0{\pm}10.0$ at estrus stage group, $16.5{\pm}3.5$ and $33.8{\pm}7.0$ at metestrus stage group, $16.7{\pm}5.8$ and $29.7{\pm}5.5$ at diestrus group, respectively. In histological findings of large follicles during each estrus cycle, the large follicles in proestrus group contain single small antrum, thick granulosa cell layers, and were $300{\sim}500{\mu}m$ in diameter and were growing follicles with PCNA-positive cells in the granulosa cell layers, and other luteinizing follicles of proestrus cycle stage were decreased in size and were thicker in wall thickness and more luteinized than those in metestrus and diestrus stage groups. The large follicles in estrus stage group contain thick granulosa cell layers and nonprominent cumulus-oocyte complexes in antrum, and were $400{\sim}700{\mu}m$ in diameter and were growing follicles with PCNA-positive cells in the granulosa cell layers. The large follicles in metestrus and diestrus stage groups contain enlarged antrums, thinner layers of walls and prominent cumulus-oocyte complexes, and were $700-950{\mu}m$ in diameter, and were nongrowing follicles without PCNA-positive cells or another large follicles contain cells with dark stainability and distinct boundary.

• Korean Journal of Ichthyology
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• v.13 no.3
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• pp.201-209
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• 2001

Annual reproductive cycle of seabass, Lateolabrax japonicus, was histologically investigated based on samples captured on the coast of the Tongyoung, South Korea. The gonadosomatic index (GSI) of females began to increase in October and reached its maximum in February. The GSI of males reached its maximum in December. The change of GSI and gonadal tissue showed that the annual reproductive cycle was classified into the following successive four stages: (1) the degenerative and resting stage from March to August, (2) the growth stage from September to November, (3) the mature stage from November to December, and (4) the ripe and spawning stage from December to March.