• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.1
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• pp.8-14
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• 2009

To prevent the food poisoning originated by consumption of shellfish contaminated with domoic acid, the quantitative analysis of domoic acid is to be very important. The stability of domoic acid at different temperature, pH and light was investigated using high performance liquid chromatography (HPLC). The mean recoveries of domoic acid in the methanol extracts from oyster (Crassostrea gigas), blue mussel (Mytilus edulis), short neck clam (Ruditapes philippinarum) and ark shell (Scapharca broughtonii) were 85.4-104.5%, 94.8-101.2%, 91.0-104.6%, and 95.7-109.6%, respectively. The working solutions of domoic acid standard were very stable for one month at $-18^{\circ}C$, $4^{\circ}C$, and room temperature. And domoic acid in the methanol extract from oyster was stable for a day at $4^{\circ}C$ and room temperature, and for a week at $-18^{\circ}C$. Therefore, this implies that quantitative analysis for domoic acid must consider the storage conditions of the standard solutions and the methanol extracts from shellfish. The standard solutions adjusted to pH 3-9 were also stable after heating at $121^{\circ}C$ for 30 min. The effect of light exposure on domoic acid was tested by exposing the methanol extracts to light. Domoic acid degraded slowly when the samples were kept in the dark (brown vial). However, following the light exposure the photodegradation became more rapid; no detectable domoic acid remained in $1.0{\mu}g/mL$ of methanol extract after 5 hours.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.1
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• pp.41-47
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• 2009

The seasonal reproductive cycle of Gomphina melanaegis collected in the coastal area of Jumunjin, between April 2006 and March 2007, was analyzed. Maturation cycle parameters such as the gonad index (GI), ovarian egg diameter, frequency of developmental stages, protein content, and RNA/DNA variation in the gonads were analyzed monthly for the 40 samples. According to the indices from histological sections, the frequency of gonad developmental stages, and the oocyte diameter, this clam has a long-term partial spawning pattern from March to October. However, GI and nucleic acid values showed that the mature stage is from March to July and that the main spawning season is August. The peak RNA and DNA contents were good indicators of sexual maturation in females and males, respectively. The variation in protein content corresponded with the RNA/DNA ratios.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1929-1932
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• 2005

We investigated the activities of autonomic nervous system during foot bathing. The effect of foot bathing was evaluated for four subjects by observing the characteristic of heart rate variability and bodily temperatures. The foot bathing was done with a commercial foot spa (Duches Co.) utilizing the four functional modes of the spa for two different temperatures of $35^{\circ}C\;and\;40^{\circ}C$. The four functional modes were clam, vibration, air bubbles, and both vibration and air bubbles. The experimental results showed that the temperature of foot and that of face right after foot bathing were not that different from each other. But, for heart rate variability, the activation of parasympathetic nerve showed distinctive increase at $40^{\circ}C$ of water temperature. In the analysis of heart rate variability for different functional modes, the change was not distinctive for different modes at $35^{\circ}$ of water temperature. However, at $40^{\circ}C$, the activation of sympathetic nerve showed distinctive increases with the increase in the complexity of functional modes.

• Journal of Aquaculture
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• v.15 no.1
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• pp.23-29
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• 2002

To develop techniques for the production of artificial seedling of Corbicula japonica, protocols for induction of spawning and larval development were developed. During the assumed spawning period of August to mid-September, attempts were first made to induce spawning by gonadal incision and UV-irradiation but all in vain. At the end of August, elevated thermal induction evoked 90 % positive response in animals maintained at $3\textperthousand$ salinity. Immersion in (1/1000~3/1000 N) ammonium hydroxide ($NH_4$OH) also induced spawning in 15~45%) of the treated animals at $3\textperthousand$ salinity. Fertilized eggs measured 86$\mum. At 23.0~24.5$^{\circ}C$, the fertilized egos developed into 4-cell stage embryos within 2 hours, trochophores 15 hours, D-shaped larvae 2 days, umbo 9 days and fully grown veligers, ready to infiltrate into the sediment, within 16 days.

• Fire Science and Engineering
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• v.19 no.2 s.58
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• pp.93-104
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• 2005

Nowadays, the arson is not common interest happening. the arson has been handled with a crime of violence along with murder, robbery and rape. because of being detrimental to the public clam. but the arson a has not been made award of a serious social problem. There is a rise in the control possibility according to a level of national concern. we have known that the last fire accident of the Deagu underground It took a heavy toll of lives and the property due to our no interest in arson. The government and regional self governing community have fully aware of the serious of the arson so that we can make arrangement for overall measures. The government should not only make up for legislation and systematize to correct a defect but also there is uniting the countermeasure system of the organs. The government establish particular research institution of the arson to consider a useful countermeasure. The investigation authorities should develop the investigation technique to arrest an arsonist. The relevant post strengthen the public relation to bring up a private organization of fire prevention in order to prevent the arson to try the government best.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.85-89
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• 1975

Heavy metal content have been determined in baby clams from March 1973 to April 1974 in Depori, Samchunpo, Korea. Monthly changes of mercury, lead, copper ana cadmium in the samples were irregular but as a whole, the content of mercury, lead, copper and cadmium were relatively high in summer season. The content of total mercury, lead, copper and cadmium in the samples ranged from 0.003 to 0.038 ppm, 0.096 to 0.931 ppm, 0.023 to 0.139 ppm and 0.009 to 0.038 ppm respectively. In the consideration of heavy metal content, it was concluded that baby clams in Depori, Samc hunpo, Korea is suitable for processing materials.

• Analytical Science and Technology
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• v.16 no.2
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• pp.166-173
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• 2003

To determine levels of PCBs in food, beef, pork, chicken, egg, mackerel, yellow croaker, anchovy, common squid and little neck clam were chosen and collected at markets in Seoul, Busan and Kwangju. Among 209 PCB congeners, 7 congeners (#28, #52, #101, #118, #138, #153 and #180) were selected as target compounds that were known as indicator congeners. Samples were homogenized, treated in alkali solution for 1 hour, and extracted with organic solvents. After extraction, extracts were cleaned up by sulfuric acid, purified on silica gel column chromatography, analyzed by dual column-HRGC/ECD and then confirmed by HRGC/MSD. As results, PCBs were detected in fish samples ranged from 0.0002 to 0.001 mg/kg. Both PCB #101 and PCB #118 were the major contributors among 7 congeners.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.4
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• pp.542-554
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• 2015

Grain size, the content of ignition loss (IL), and the concentrations of chemical oxygen demand (COD), acid volatile sulfide (AVS), and trace metals (Fe, Mn, Cu, Pb, Zn, Cd, Cr, As, and Hg) in surface sediments from the Taehwa River estuary, Ulsan, were measured to evaluate pollution levels and potential ecological risks of organic matter and trace metals in estuarine sediment. The mean grain size (Mz) of sediments in the study region ranged from $-0.8-7.7{\varphi}$ (mean $2.8{\pm}2.4{\varphi}$). Surface sediments in the upstream region of the Taehwa River were mainly composed of coarse sediments compared to the downstream region. The concentrations of IL, COD, AVS and trace metals in the sediment were much higher at downstream sites of Myeongchon Bridge in the vicinity of industrial complexes than at upstream sites of those in the vicinity of the residential areas due to the anthropogenic input of organic matter and trace metals by industrial activities. On the basis of several geochemical assessment techniques [sediment quality guidelines (SQGs), enrichment factor (EF), geoaccumulation index ($I_{geo}$), pollution load index (PLI) and ecological risk index (ERI)], the surfaces sediments in the study region are not highly polluted for trace metals, except for As. However, the higher concentrations in downstream study regions of the Taehwa River could impact benthic organisms including shellfish (i.e. Manila clam) in sediments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.5
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• pp.567-575
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• 2017

To understand the geochemical characteristics of Gomso Bay, which features extensive Manila clam, we measured various geochemical parameters, organic matter, and trace metals (Cu, Cd, Pb, Zn, Cr, Hg, As and Fe) of intertidal and subtidal surface sediments in 2011. The surface sediments consisted of sedimentary facies including gravel (0.21%), sand (61.1%), silt (32.1%), and clay (6.5%). The chemical oxygen demand (COD) and acid volatile sulfide (AVS) values in most areas were below sediment quality criteria (COD, $20mg/g{\cdot}dry$; AVS, $0.2mg/g{\cdot}dry$). Trace metals in the surface sediments were below pollution thresholds, except for As (morderately polluted). Sediment quality was evaluated using the trace metal pollution load index (PLI) and ecological risk index (ERI), which showed that sediments were generally not polluted and at low risk; however, values along the outer bay were higher. We expect these results will be valuable for sustainable aquaculture prodution and environmental management in Gomso Bay.

• The Korean Journal of Malacology
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• v.13 no.2
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• pp.131-141
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• 1997

전북 김제시 심포에서 1994년 1월부터 12월까지 월별로 채집된 백합 Meretrix lusoria의 생식세포형성과정 및 생식주기를 , 조직학적으로 조사한 결과는 다음과 같다. 백합은 자웅이체이고 난생을 하며, 생식소는 내장낭의 간중장선의 하부로부터 족부의 근육부근까지 분포하며, 성숙되면 팽대되지만 방란, 방정 후에는 위축된다. 생식소는 많은 난자형성여포들과 정자형셩여포들로 구성되어 있다. 여포에는 호산성 세포와 미분화간충직들이 들어 있는데, 이들은 초기 생식세포의 영양물질로 제공되고 있으며, 생식소가 발달함에 따라 점차 소실된다. 초기활성기의 난원세포는 직경 10$\mu\textrm{m}$ 내외이며, 초기 난모세포는 난병을 여포벽에 부착한 채 성장을 하여 70$\mu\textrm{m}$ 내외의 완숙란으로 된다. 정원세포가 성장을 하여 정보세포, 정세포를 거쳐 변태를 마친 정자는, 정자형성소낭의 중앙 내강에 정자속을 형성한다. 방란, 방정을 마친 생식소는, 일부 미방출된 생식세포가 퇴화 흡수되면서 비활성기를 지나 이듬해 수온상승과 더불어 새로운 발달을 시작한다. 생식주기는 연속적인 5단계로 구분할 수 있는데, 초기 활성기(1-3월), 후기 활성디 (2-5월), 완숙기(4-8월), 부분 방출기(6-9월), 퇴화 및 비활성기(9-2월)로 구분할 수 있다. 산란은 6월 (22$^{\circ}C$)부터 9월 ($25^{\circ}C$)까지 지속되지만, 산란성기는 7월(27$^{\circ}C$)-8월(28$^{\circ}C$)이다. 생식소지수는 1월에 0.58을 나타내며 5월에 4.60으로 최대값을 나타낸 후, 6월부터 점차 감소하기 시작하여 12월과 1월에는 1.0미만에 머무른다.