• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.5
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• pp.477-483
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• 1985

This paper describes seasonal changes of total length, hepatosomatic index (HSI), fatness, egg-diameter composition, and fecundity of the longchin goby Chasmichthys dolichognathus(HILGENDORF). The specimens used were captured in the tide pool of Tongbaekseom, Pusan, Korea from February 1983 to January 1984. The age of longchin goby, tested by size frequency, was believed to be usually one year which grows to 8.0 cm in total length. The annual variations of HSI reached the maximum in the early spring when the gonad was actively growing and decreased during the spawning season from April to July. The coefficients of fatness were represented low values for the spawning periods. Frequency distribution of the egg diameter of mature ovary has three modes: one is the evident mode of the ripe eggs group, and the other two are modes of maturing and immature eggs groups. And an individual is considered as spawns one in the spawning season. Relationships between the fish size in total length (TL cm) and the number of ovarian eggs(F), the fish weight (BW g) and the number of ovarian eggs are indicated by the exponential equation respectively : F=42.585 $TL^{1.608}$, F= 524.589 $BW^{0.475}$.

• Korean Journal of Environment and Ecology
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• v.38 no.4
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• pp.388-404
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• 2024

The focus of conserving plant diversity at the national level includes endemic species restricted to specific regions. This study thus aimed to investigate and evaluate the current distribution status of the Pulsatilla tongkangensis Y.N. Lee & T.C. Lee, one of Korea's endemic plants. The study also examined the vegetation environment of its habitat and assessed the structure of each population. Furthermore, the performance variable of each population was comparatively evaluated, and its annual growth characteristics were also observed. The distribution area of the P. tongkangensis is largely divided into limestone cliffs, ridge rocks, mountain peaks in limestone regions, and sandy soil areas resulting from weathering. Plants in the same distribution area were categorized based on their geographical location, which reflected their respective habitats. According to the population structure evaluated using the number of measured leaves numbers, the plants were categorized into stable and relatively unstable populations. A relatively young population was observed at the top of mountains and rocky ridges of limestone areas and sandy soil areas resulting from weathering. The number of mature individuals was the highest in the population observed around limestone cliffs. In contrast, the population near the top of the limestone mountain range had more leaves , but the plants were of short stature and had the fewest inflorescences. The individuals distributed in limestone cliffs grew, produced, and dispersed seeds for an extended period following establishment. The growth of individuals was limited due to environmental factors in the habitat of distribution areas, including ridges, mountain tops in limestone regions, and sandy soil areas resulting from weathering. It was assessed to have a comparatively brief life cycle compared to that of the plants found on limestone cliffs. P. tongkangensis began flowering in early spring, and both fruit maturation and seed dispersal were completed before the onset of summer. The habitats were determined to receive around seven hours of sunlight per day during the summer, which was considered suitable for establishing a life cycle for the P. tongkangensis, a species requiring strong sunlight for growth to establish and success in a dry environment. Considering the status data gathered from this study, the P. tongkangensis was classified as an endangered species (EN). In addition, the collected data are expected to provide important information for the IUCN Red List of Threatened Species. Therefore, we proposed that the P. tongkangensis holds significant value as a core distribution site, given the observation of species with diverse characteristics on limestone cliffs in Pyeongchang-gun and Jeongseon-gun, Gangwon-do.

• Journal of Korean Society of Forest Science
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• v.108 no.1
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• pp.127-132
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• 2019

This study aimed to investigate the differences in habitat environment and characteristics of small rodent populations with time elapse after thinning in Japanese larch (Larix kaempferi) plantations, Mt. Janggun, Gyeongbuk Province, South Korea. We found that there were significant differences in habitat environment, number of tree, shrub stems, coverage of overstory, midstory, rock and number of coarse woody debris (CWD) between thinned and unthinned forest stands. We captured four small rodent species. Total number of captured small rodent were higher in thinned stands. Male-to-female ratio of Apodemus agrarius, and A. peninsulae were both the highest in forest stand 3 year after thinning. The differences in number of captured and sex ratio of small rodents might be related to habitat environment between thinned and unthinned stands. Thus, thinning can provide good habitat for small rodents by developing understory vegetation and increasing CWD in Japanese larch plantations. These results suggest that forest management through maintenance of CWD and induction of midstory and understory vegetation after thinning is necessary to maintain small rodents diversity.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.225-226
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• 2000

갈조 모자반속 식물의 괭생이모자반은 1년생으로 조하대에 생육하는 해중림 구성 해조로서 울릉도와 제주도를 포함 우리나라 동ㆍ남ㆍ서해에 널리 분포하는 종이다(Kang, 1966). 이종의 생활사에 관하여는 Uchida(1993)가 실내배양을 통하여 밝힌 바 있으며, Okuda(1987)에 의해 자웅동주개체와 가을철의 성숙에 관한 생리. 생태가 밝혀졌으며, 실내배양을 통하여 가을에 성숙하는 조체의 난방출, 배발생 및 광합성속도의 계절변화가 밝혀졌고(Honda와 Okida, 1989), 곡구ㆍ산전(1988)에 의해서 마츠시마만에서의 괭생이모자반 군락의 주년변화와 생산력에 관한 생태가 밝혀지는 등 특히 이종을 식용으로 하는 일본을 중심으로 다양한 분야에 걸쳐서 많은 연구가 이루어져 왔다. (중략)

• Korean Journal of Ichthyology
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• v.35 no.4
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• pp.333-339
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• 2023

The aim of this study was to collect information regarding the sex ratio, size at sexual maturity, and the primary spawning period of Hexagrammos otakii. The sex ratio (female : male) was observed to be 1 : 1.2 (n =739 : 906, with females comprising 81.6% of the population). The gonadosomatic index (GSI) exhibited its highest values in November for females and October for males, coinciding with the primary spawning period from November to January. The total length required for 50% sexual maturity was determined through a logistic regression model and found to be 23.1 cm for females.

• The korean journal of orthodontics
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• v.28 no.3 s.68
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• pp.409-417
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• 1998

The 123 left hand-wrist radiographs and menarcheal ages attained by direct questioning to patients or her mothers are used, in order to exploit the relationship between the bone maturity and the menarcheal age of girls in adolescence. The results were as follows, 1. The mean age at menarche was $12.31{\pm}0.99$. 2. The onset of menarche occurred at SMI 7 and SMI 8 ($73.33\%$). The onset of menarche was correlated with skeletal age rather than chronological age. 3. There was statistically significant difference among the time passed from menarche according to skeletal maturity level. 4. The distal epiphyseal union of radius began at about 20 months after menarche. 5. In comparision of the time intervals from menarche to radial epiphyseal fusion among early, average, and late menarcheal age groups, late group had lesser time interval than other two groups.

• Development and Reproduction
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• v.12 no.2
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• pp.169-181
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• 2008

Reproductive ecology of the silver pomfret, Pampus argenteus were investigated by histological observations and morphometric data. Samples were collected by the stow net at the coastal area of Jaun-Do, Muan-gun, Korea, from January to December, 2006. P. argenteus is dioecious, the ovary is composed of many ovarian lobules, showing a pair of saccular structure, and the testis is composed of many seminiferous lobules, showing a pair of lobular structure. From February (growing stage) to September (after spawning), monthly changes in the gonadosomatic index, hepatosomatic index, and condition factor in females and males showed similar patterns with the gonad developmental phases. Judging from the results of their indice, it is assumed that spawning in females and males occur from May to July. The reproductive cycle can be classified into five successive stages in females: early growing stage (February to March), late growing stage (March to April), mature stage (March to July), ripe and spent stage (May to July), and recovery and resting stage (July to February); in males, the cycle can be divided into four successive stages: growing stage (February to April), mature stage (March to June), ripe and spent stage (May to July), and recovery and resting stage (July to February). According to the frequency distributions of egg diameters in the breeding season, P. argenteus is presumed to be spring-summer spawning species and polycyclic species to spawn 2 times or more during one spawning season. Number of total eggs in absolute fecundity were proportional to body length and body weight, respectively. Number of total eggs in absolute fecundity per body weight were also proportional to the body length, but if the increase of body weight considerably increased, rather total eggs in relative fecundity decreased with the increase of body weight. Percentage of first sexual maturity of P. argenteus were over 50% in females and males of 12.1 to 15.0 cm in body length, and 100% for fishes over 18.1 cm in length. Therefore, both sexes were regarded to be sexually mature at one year of age.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.6
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• pp.563-574
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• 1986

The structure of gonads, gametogenesis and reproductive cycle of the jackknife clams, Solen strictus and Solen gordonis were investigated mainly by histological observation. The first species used were monthly sampled at the coastal area of Dadaepo, Pusan, Korea and Naechodo, Kunsan, Korea for one year from February 1982 to January 1983. The second species were monthly sampled at the sand beach of Dadaepo, Pusan, Korea, from February 1982 to January 1983. Sexualities of Solen strictus and Solen gordonis are dioecious, and these species are oviparous. The gonads are irregularly arranged from the subregion of mid-intestinal gland in visceral cavity to reticular connective tissue of foot. The ovary was composed of a number of small ovarian sacs and the testis was composed of several testicular lobuli which from the tubular structure. Early multiplicating oogonium was about $10{\mu}m$ in diamater. Nucleus and nucleolus, at that time, were distinct in appearance. Each of the early growing oocytes made an egg-stalk, connected to the germinal epithelium of the ovarian sac. A great number of undifferentiated mesenchymal tissue and eosinophilic granular cells are abundantly distributed in the ovarian sacs in the early development stages. With the further development of gonad, these tissue and cells gradually disappeared. Then the undifferentiated mesenchymal tissue and eosinophilic granular cells function as nutritive cells in the formation and development of the early stage germ cells. Mature oocytes were free in the lumen of ovarian sacs and gradually become round or oval. Ripe oocyte was about 80 to $90{\mu}m$ in diameter. With the further development of testis, each of the testicular lobuli formed stratified layers composed of spermatogonia, spermatocytes, spermatids and spermatozoa in groups on the germinal epithelium. After spawning, the gonad gradually degenerated, and disorganized completely. Then new differentiated tissues were rearranged next year. The annual reproductive cycle of those species could be classified into five stages; multiplicative, growing, mature, spent, degenerative and resting stage. It seems that the spawning season is closely related to the water temperature, and the spawning of Solen strictus occurs from June to July at above $20^{\circ}C$ in water temperature. The peak spawning season appeared in June at Dadaepo and in July at Kunsan, The spawning of Solen gordonis occurs from May to June with the peak spawning season in June. Percentages of the first maturity in female of Solen strictus ranging from 5.1-6.0 cm and 7.1-8.0 cm in shell length were $50\%$ and $100\%$, respectively.

• Proceedings of the KAIS Fall Conference
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• 2005.05a
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• pp.297-300
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• 2005

1970년대 식용을 위한 양식을 목적으로 일본에서 수입된 황소개구리가 국내 하천과 호서생태계에 큰 피해를 주었으나, 최근 급속히 그 개체수가 줄어든 것으로 추정되므로 이번 연구에서는 국내에 서식하는 북미산 황소개구리의 유전자 분석을 통하여 개체동태군에 대한 유전적 연관을 조사하였다. 이를 위하여 전라남도 지역에서 서식하는 황소개구리를 채집하여 이미 발표된 북미산 황소개구리와 미토콘드리아 ND1/tRNA 유전자 1215bp의 염기서열을 비교, 분석하였다. 북미산과 비교하였을 때 조사한 국내 서식 개체 모두에게 ND1/tRNA 유전자 1개 위치에서 염기변화가 발견되었으나 이는 도입 개체군의 유전자인지 국내 특이변이가 진행된 것인지 확실하지 않다. 또한 조사한 개체 일부에서 유전자 염기서열의 6위치에서의 변이가 발견되었으나 국내 서식 황소개구리는 미국산 황소개구리와의 유전적 차이가 거의 없으며, Kimura-2-parameter 분석결과 국내 서식 황소개구리 개체 내에서 $98.7\%\~100\%$의 높은 유사성을 보여 종내 유전적 차이가 거의 없는 것으로 보인다. Neighbor-Joining과 Maximum Parsimony 분석 결과, cluster를 이루는 개체군의 차이를 보였으므로 개체들이 분화되어 나온 시점과 위치가 다른 것으로 확인되었지만 장흥, 영암, 고흥의 개체가 국내 도입시기의 개체군에 속하며 광주, 남평 지역의 개체군이 고흥의 한 개체로부터 분화되어 나왔음을 추정할 수 있다. 이러한 결과로부터 국내에 서식하는 황소개구리가 도입 후 지역 특이적 분화가 일어났다고 결정하기는 무리가 있으며, 이와 같이 유전적 유전도가 높은 개체들간의 교배에 따른 유전적유전적 다양성의 감소가 최근에 관찰되는 국내산 황소개구리의 급격한 감소원인들 중의 하나일 가능성을 시사한다.년도) 18,756, 2045(년도) 22,595, 시장점유율 증가로 인한 수출액 증가분 누적(억원) : 2015(년도) 3,411, 2025(년도) 8,847, 2035(년도) 14,433, 2045(년도) 18,005 또한 시나리오 비교평가를 실시하여 본 결과, 본 연구에서 정의한 순편익 누적(Cumulative Net Profit) 변수를 적용하면 현재 연구비 추세 대비 $30\%$ 까지 연구비를 증가 시키는 것이 효율적임을 알 수 있었다.성, 생산 용이성, 제품 디자인의 우수한 정도가 a=0.01 수준 하에서 유의적으로 추정되었다. 이들 변수들 중에서 품질경쟁력에 가장 큰 영향을 미치는 측정변수는 제품의 기본 성능, 수명(내구성), 신뢰성, 제품 디자인의 순서로 추정되었다. 이것은 한국 제조업이 아직 산업 디자인이 품질경쟁력에 크게 영향을 미치는 성숙단계에 이르지 못하였음을 의미한다. (2) 제품 디자인에게 영향을 끼치는 유의적인 변수는 연구개발력, 연구개발투자 수준, 혁신활동 수준(5S, TPM, 6Sigma 운동, QC 등)이며, 제품 디자인은 우선 품질경쟁력을 높여 간접적으로 고객만족과 고객 충성을 유발하는 것으로 추정되었다. 상기의 분석결과로부터, 본 연구는 다음과 같은 정책적 함의를 도출하였다. 첫째, 신상품 개발과 혁신을 위한 포괄적인 연구개발 프로젝트를 품질 경쟁력의 주요 결정요인(제품의 기본성능, 신뢰성, 수명(내구성) 및 제품 디자인)과 연계하여 추진해야 할 것이다. 둘째, 기업은 디자인 경영 마인드 제고와 디자인 전문인력 양성을, 대학은 디자인 현장 업무를 통하여 창의력 증진과 기획 및 마케팅 능력 교육을, 정부는 디자인 기술개발 및 디자인 교육지원의 강화를 통하여 각각 디자인 경쟁력$\rightarrow$품질경쟁력을 제고시켜야 할 것이

• The Korean Journal of Malacology
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• v.23 no.2
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• pp.199-208
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• 2007

The gonad index, gonadosomatic index, the condition index, reproductive cycle, first sexual maturity, and sex ratio of the hard shelled mussel, Mytilus coruscus were investigated by using histological analysis and morphometric data. Specimens were collected monthly in Kyeokpo, western Korea from January to December, 2006. The gonad index reached a maximum in February, and minimum in September. Both the monthly variations of the gonad index (GI) and the gonadosomatic index (GSI) reached a maximum in February. After that, their values continually decreased between March and April because of spawning. The monthly variation of the condition index coincides with the GI and the GSI. The spawning period was from February to April, with the main spawning occurring between February and March. The reproductive cycle of this species could be classified into six stages: early active stage (November to January), late active stage (November to February), ripe stage (December to April), partially spawned stage (February to April), degenerative stage (April to October), and resting stage (June to December ). Percentages of sexual maturity was over 50% for the female and male hard shelled mussels that ranges from 40.1 to 50.0 mm in shell length. The percentage was 100% for those that are over 50.1 mm. The sex ratios of females to males over 40.1 mm in shell length were not significantly different from a 1:1 sex ratio $(x^2\;=\;0.63,\;p\;>\;0.05)$. No evidence of hermaphroditism was found in histological sections of any hard shelled mussel examined.