• Journal of Practical Agriculture & Fisheries Research
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• v.16 no.1
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• pp.135-141
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• 2014

Olive flounder (Paralichthys olivaceus) has a great potential value for aquaculture in Korea. The theoretical sex ratio of this flounder is close to 1:1 as it is in many other type of fish. However, according to the size selection during artificial seedling production, there is a possibility of unbalanced sex ratio. The actual flounder culturing needs female seedlings because of faster growth than male in economically. However, little is known about the sex ratio of cultured flounder. The six populations consisted of three wild populations and three cultured populations were analyzed for investigating the sex ratio. The sex ratio of wild populations ranged from 1.10 to 1.93 in female and 0.52 to 0.91 in male. And the sex ratio of cultured populations ranged from 0.20 to 2.15 in female and 0.46 to 4.88 in male. This result indicated that the sex ratio of cultured flounder varies depending on the size selection method.

• Korean Journal of Poultry Science
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• v.43 no.1
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• pp.39-45
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• 2016

This study was carried out to evaluate performance and uniformity of White Korean native ducks collected from two areas in Korea. White ducklings were selected from all ducklings that were hatched from hatchery eggs of Korean native ducks. A total of two hundred forty white ducklings (1-d-old) were used in this work and were divided into 4 groups (4 replicates/group, 15 birds/replicate) with $2{\times}2$ factors (2 groups, J, H; genders, male and female). Weekly body weight of H groups was higher than that of J groups (P<0.05). Also, weekly body weight of male ducks was higher compared to that of female at 6~8 wk old (P<0.05). Uniformity of J groups was higher than that of H groups at the age of 1 wks old (P<0.05), and that of female duck was higher than that of male at the age of 6 wks old (P<0.05). Body weight gain of H group was higher than that of J group (P<0.05), and that of male duck was higher compared to that of female at 6~7 wks old (P<0.05). Feed intake of H group was higher compared to that of J group (P<0.05), but there was no significant difference between male and female on feed intake. On feed conversion ratio, J group was higher than H group at 4~5 wks, 7~8 wks and 0~8 wks old (P<0.05), and feed conversion ratio of male duck was higher than that of female at 1~2 wks, 5~6 wks and 6~7 wks old. Finally, these results was tended to show that performance of H groups was higher than that of J groups. Further researches need to carry out to commercial White Korean native ducks on performance and uniformity as well as meat quality and genetic characteristic.

• The Korean Journal of Malacology
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• v.18 no.2
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• pp.83-91
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• 2002

Reproductive cycle of natural population and artificial control experiments of gonadal development by the conditions of water temperatures-feeding and starvation of Ruditapes philippinarum were investigated by histological observations. The reproductive cycle of natural population in females and males can be categorized into five successive stages; early active (February to March), late active (April to May), ripe (April to August), partially spawned (May to October), and spent-inactive stage (August to March). In the artificial control experiments, gonadal development of this species was inhibited by the low water temperature (10$^{\circ}C$). In the experimental group which was exposed to artificial high water temperatures of 19$^{\circ}C$ and 22$^{\circ}C$, gonadal development was accelerated by the higher water temperatures and was faster (about one month) than that in natural populations. In the high water temperatures-feeding experimental group, the gonadal developmental phase was faster in the small-size group than that in the large-size group, and was faster in lower water temperature (10$^{\circ}C$)(p=0.01). The gonad developmental phases in the high water temperature (22-28$^{\circ}C$)-starvation experimental group showed faster (paired sample t-test, p=0.004) than those in the high water temperature-feeding group in females and males. In the high water temperature-feeding experimental group of female and male gonadal developments of small sized group were more sensitive than those in large sized group after 42 days cultivation, However, the gonadal development of male was more sensitive to the lower water temperature than female. On the whole, sexual maturation in the high water temperature experimental group was faster than those in the low water temperature group, and showed a significant difference (paired sample t-test, p=0.001) between female and male. In the starvation experimental group after 42 days, gonadal developments in the high water temperature-large male group showed faster than those in the high water temperature-large female group. However, in small size, gonad developmental phases showed the same pattern between feeding and starvation experimental groups. During the main spawning season, in the high water temperature-starvation experimental groups in females and males, their gonadal development showed faster than that in higher water temperature-feeding experimental group regardless of their sexes and individual sizes and showed a significant difference (paired sample t-test, p=0.004).

• Korean journal of applied entomology
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• v.59 no.3
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• pp.243-250
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• 2020

Two meridic diets, N4 and N6, containing pinto bean, wheat germ, soybean, whole milk and sucrose as main nutrients were developed for rearing Spodoptera frugiperda (Noctuidae) larvae. Six larval instars were observed when neonate larvae were individually raised on these diets in small petri-dishes (ø 50 × 10 mm, 19.6 ㎤) at 25℃ and 15:9 h (light:dark) photoperiod. The average pupation rate of 97.8% on the N4 diet was significantly higher than the rate of 85.6% on N6 diet. The emergence rates were 92.0% on N4 diet and 93.5% on N6 diet, with a non-significant difference. The larval periods were 17.9 and 17.7 days for females, and 18.7 and 18.5 days for males, for N4 and N6 diets, respectively, with non-significant differences between diets and sexes. The pupal periods on both diets were identical (11.1 days for females and 12.8 days for males), despite differences between sexes. The pupal weights of both sexes on N4 diet were identical with a value of 257 mg, whereas those on N6 diet were 256 and 263 mg for females and males, respectively, with a non-significant difference. The longevity of female adults that emerged on N6 diet was 13.8 days and longer than 8.6 days on N4 diet. The pre-oviposition periods were 5.0 and 4.2 days on the N4 and N6 diets, respectively, with a non-significant difference, however, the oviposition period of 6.5 days on N6 diet was longer than the period of 3.9 days on N4 diet. The effective fecundity on N6 diet was 1,392 eggs (maximum 1,776) and was higher than that of 942 eggs (maximum 1,694) on N4 diet, with a non-significant difference. The egg hatching rates on N4 and N6 diets were 79.2 and 79.8%, and egg periods were 3.0 and 2.9 days, respectively, with non-significant differences.

• Korean journal of applied entomology
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• v.46 no.1 s.145
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• pp.1-4
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• 2007

Pachynematus itoi Okutani, belonging to the family Tenthredinidae(Hymenoptera), which infested Larix kaempferi(Lamb.) Carriere in the middle areas of Korea, is reported for the first time from Korea. External characteristics of adults are briefly redescribed with photos. Also its damages and bionomic data are discussed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.2
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• pp.85-89
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• 1997

한국서해안 격열비열도 근해산 문치가자미의 연령과 성장을 조사하기 위하여 1992년 9월부터 1993년 8월까지 매월 정기채집한 256개체의 이석을 연령형질로서 사용하여 조사 분석한 결과를 보면, 이석의 투명대와 불투명대는 년 1회 형성되었으며 투명대 형성시기는 7월이고 불투명대 형성 시기는 2월에서 4월로 이는 산란종기(2월)와 일치함을 보였다. 연령별 체장 (LT)과 연령(t)을 von Bertalanffy 성장식에 적용하여 수컷은 Lt=313.7[1-exp{-0.4342(t+0.9017)}, 암컷은, Lt=458.1[1-exp{-0.2368(t+0.1934)}과 같은 관계식을 구하였다. 또한 암컷과 수컷의 성장속도는 2세까지는 별다른 차이를 보이지 않았으나, 3세어 이상에서는 암컷이 수컷보다 월등히 빠름을 나타내었다. 본 연구에서의 최고령어는 암수 각각 5세와 6세였다.

• Parasites, Hosts and Diseases
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• v.33 no.2
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• pp.139-144
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• 1995

Thelazia ccllipaedc were observed from a 7-month old baby who lived in Uijongbu in 1989 and from a 42-year old man who lived in Anyang in 1994. These are the 23th and 24th records of human thelaziasis in Korea as the literature are concerned.

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.46-47
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• 2007

본 논문은 소의 모색에 관여하는 Melanocortin I recepter (MCIR) 유전자의 염기서열을 기초로 정확하게 한우와 젖소를 구분할 수 있는 단일 염기 변이를 이용하여 기존의 방법보다 2배 이상으로 빠른 속도로 한우와 젖소를 판별할 수 있는 multiplex PCR 기술에 관한 것이다. 또한, 동 기술에 적용된 기술에는 기존의 방법으로는 동시 판별을 할 수 없었던 소의 암수 구분이 가능하도록 수컷 판별을 위한 표지 유전자인 SRY 유전자를 적용함으로써 한우와 젖소 그리고 압수를 고속으로 동시 판별이 가능하게 되어 젖소가 한우로 둔갑되는 현재의 불법 유통의 문제점을 해결해 주는 새로운 방법이 될 수 있을 것으로 사료된다.

• The Korean Journal of Zoology
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• v.17 no.1
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• pp.17-22
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• 1974

The G-6-PD (glucose-6-phosphate dehydrogenase) activity, the first step in the pentose phosphate shunt, of rat livers during prenatal and pstnatal development in different sexes was studied. The enzyme activity is very high (54.2 units) at 16 days of embryo ad then decreases to a low level (17.6 units) at 13days after birth. There are significant increase between 13 and 15 days of age and continuously increases to the level of 53.2 units at 19days of age. The G-6-PD activity in female rat livers was slightly higher than in males.

• Korean journal of applied entomology
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• v.47 no.1
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• pp.5-8
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• 2008

Three species: Anorthoa angustipennis (Matsumura), Harutaeographa stenoptera (Staudinger), and Cerastis pallescens (Butler), are recorded for the first time from China, and Nikara castanea (Moore) is newly added to the fauna of Northeast China. The image of adult, genitalic characteristics, and the distributions are given as necessary.