• Journal of Aquaculture
• /
• v.16 no.4
• /
• pp.229-232
• /
• 2003

Survival with various conditions (water temperature, salinity and air exposure) and sand immersion ability for release of surf clam, Spisula sachalinensis spats, which were artificially seed produced, were investigated. Survival with water temperature conditions of spats showed no difference within the range of 4∼28 $^{\circ}C$ for 10 days. In salinity conditions, survival (%) of spats showed more than 50% in over 22 psu. In air exposure conditions, survival (%) of spats air exposed for 12 hours was no difference within below 2$0^{\circ}C$, however, that of spats air exposed for 16 hours showed below 50% at $25^{\circ}C$. In sand immersion ability, the immersion time was increased with the increase of shell length, and the immersion rate was decreased. Spats of below 15 mm in shell length were emersed more than 90% within 10 min. There was no difference in the immersion time and the immersion rate with the grain sizes of the sand bottom.

• The Korean Journal of Malacology
• /
• v.26 no.2
• /
• pp.165-170
• /
• 2010

The location of the style sac and morphology of the crystalline style were described morphologically in three bivalve species (Tegillarca granosa, Mytilus galloprovincialis and Saxidomus purpuratus) which inhabited in different area. The style sac of them was connected to the posterior stomach. There was the crystalline style in the style sac. The crystalline style of three species was long circular cone of translucent gelatin form, which was hard and elastic. There was a red-yellow and spiral filament inside the crystalline style of Tegillarca granosa and Mytilus galloprovincialis. A white and long tube was located from basal portion to the end of crystalline style in Saxidomus purpuratus. RLC (relative length of crystalline style) of Tegillarca granosa, Mytilus galloprovincialis and Saxidomus purpuratus was 47.69, 48.97, 64.20% and RWC (relative weight of crystalline style) was 0.54, 0.54, 0.39%, respectively.

• Korean Journal of Environmental Biology
• /
• v.25 no.2
• /
• pp.107-114
• /
• 2007

Radiation at very low doses frequently has a stimulating or hermetic effect on growth of organism. Effects of growth and survival rate on various dose of gamma irradiation in the farm culture of juvenile abalone (Haliotis discus hannai) were determined in Hallim (Jeju) from February 2004 to January 2005. The initial shell length of abalone juveniles in this study was average $3.45{\pm}0.4cm$. A change of growth after irradiation $(0{\sim}20Gy)$ was observed for 48 weeks. The highest growth rate was observed in 4 Gy-irradiated group and the lowest growth rate was observed in 20 Gy-irradiated group. The additional research about biochemical changes on juvenile abalone after irradiation should be accomplished. Continuous study for gamma radiation-induced hormesis on growth and metabolism of juvenile abalone will further induce the creation of value in ocean industry.

• 재활복지
• /
• v.18 no.4
• /
• pp.75-93
• /
• 2014

This study attempted to verify the impacts of the level of satisfaction in the user of alternative materials among people with visual impairment on their social participation, and the mediation effect of self-efficacy during such process. The subject of the study was the visually impaired who were live in Gyeonggi Province and were registered in the Korea Blind Union. The data of final 120 participants through a telephone survey were analyzed. The subject of the study used the recorded materials the most for the purpose of leisure and information research mainly at the braille library. The analysis of the mediation effect demonstrated that the level of satisfaction in the user of alternative materials among people with visual impairment had a statistically significant influence on social participation, and self-efficacy had a full mediation effect. These results imply the importance of alternative materials to assure the right to information access which can ultimately expand the social engagement of the visually impaired. Based on these study results, political suggestions are proposed to vitalize alternative materials in the future.

• Journal of Marine Life Science
• /
• v.7 no.2
• /
• pp.163-170
• /
• 2022

In this study, the results of hybridization were evaluated by analyzing the biomarkers of Haliotis discus hannai and hybrid abalone (H. madaka♀^*H. discus discus♂) in marine net cage. The survival rate was similar both experimental groups, but the growth (shell length) was about 10% faster in hybrid abalone. The deformity of respiratory pore in the hybrid abalone was about 6% lower than H. discus hannai, and the shell depression was about 15% lower in the hybrid abalone. In the biochemical composition, crude protein was about 3.1% higher in hybrid abalone, and showed similar values except for the crude protein. In the histological structure of the hepatopancreas, which performs the functions of digestion, absorption and detoxification of abalone, good results were obtained in the hybrid abalone. On these results, it is judged that the hybrid abalone will have high aquaculture productivity in the aquaculture environment.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.31 no.6
• /
• pp.35-39
• /
• 2002

최근, 산업의 발달로 인하여 생활수준이 향상되어 대량생산과 대량소비현상이 발생하고 도시의 밀집도가 높아 단위 면적당 거주하는 인구가 증가되면서 거주지역에서 발생되는 부산물이 현저히 증가되어 환경측면에서 복합적인 환경문제에 직면해 있다. 최근까지 대책마련에 고심하고 있는 도시에서 발생된 다량의 쓰레기 처리문제는 경제적인 측면에서 몇 년 전 까지는 대부분을 매립에 의존해 왔으나, 매립 방식에 의존하였으나 지가 및 공사설비의 상승, 일부 비위생적으로 조성된 매립장에서 배출되는 침출수 및 악취 등의 환경오염이 심각한 사회문제로 대두되면서 매립장의 확보나 증설은 해당 지역주민의 반발로 지방자치단체의 골치 아픈 과제로 등장하였다. 이러한 문제점을 보완하기 위해, 최근에는 매립지 확보의 어려움과 환경보존을 위하여 쓰레기를 정적이고 위생적으로 처리하기 위하여, 소각시설이 표 1과 같이 증가하고 있으나 소각 때 발생하는 다이옥신 등 인체에 치명적인 오염을 유발시키기 때문에 소각로 건설에 대한 환경운동단체와 주민들의 반발이 거세게 제기되고 있는 현실이다. 이러한 영향에 의해 앞으로는 소각보다는 쓰레기 자체를 감량.재사용.재활용하는 처리방식이 표 1과 같이 증가되는 현실이다. 쓰레기를 소각하는 것은 제 2오염을 유발시키고, 소각장 건설비용과 유지관리에 많은 예산이 소요된다. 쓰레기소각장을 건설할 때, 인근주민이나 환경단체로부터 반대의견에 직면하게 되는데, 그 사유는 쓰레기 처리과정의 전 단계인 반입.공급 과정에서 악취발생과, 후단계인 소각설비에서 발생되는 배출가스 오염원을 완전히 제거하라는 것이다. 최근에는 소각장의 설계.시공과정에서 최대한 악취발생과 확산을 억제하는 시설에 투자를 하고 있으며, 또한 주민 편익 시설과 부대 복리 후생시설은 소각시설 주변지역 주민틀의 소각시설에 대한 부정적 이미지를 불식시키며, 외부 방문객이나 운영 관리 요원들에게 쾌적한 환경조성과 업무효율 및 근무환경의 개선에 일익을 담당하고 있다. 본 고는 환경 친화적인 쓰레기 소각장을 설계하는 측면에서 1998년도에 턴키방식으로 발주되었고 2001년 12월에 준공하여 운전하고 있는 경기도 구리시 자원회수시설의 환기설비에 적용된 설계 및 시공개념을 소개하고자 한다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.2A
• /
• pp.113-120
• /
• 2010

The use of Concrete filled circular hollow steel section (CFCHS) members in bridge design is a relatively new concept. The most important part of the design and durability of such structures is the design and the construction of the joints. In the design of recently constructed steel-concrete composite bridges using CFCHS truss girders for the main load carrying structure, the fatigue verification of the tubular spatial truss joints was a main issue. Welded CFCHS joints are very sensitive to fatigue because the geometric discontinuities of the welds lead to a high stress concentration. New research done on the fatigue behaviour of such joints has focused on CFCHS N-joints, directly welded, with finite element analysis method. A commercial software, ABAQUS, is adopted to perform the finite element analysis on the N-joints. This paper is main focused on these topics, including hot spot stress.

• The Korean Journal of Malacology
• /
• v.32 no.3
• /
• pp.231-240
• /
• 2016

Techniques were developed for holding and conditioning of Pacific oysters, Crassostrea gigas, in a closed recirculating system. Experimental adults were used 500 oysters ( x two system, total 1,000 oysters) which were collected in $20^{th}$ March 2016 from long-line aquaculture farm at the south coast of Korea. During conditioning periods concentrated live microalgae as Isochrysis sp. $15{\times}10^7cells/mL$, Tetraselmis sp. $2{\times}10^7cells/mL$ and Pheaodactylum sp. $18{\times}10^7cells/mL$ were added 5 L every day, respectively which micro algae were functioned as diets and biological filter. Over all experimental periods total water exchange rate was 21.3% (daily 0.5%). Over 42 days conditioning, female and male oysters were maturated 90.9% and 94.4%, respectively. Survival rate was 98.7%. Mean shell hight (8.3 mm), total wet weight (19.2 g), meat wet weight (5.0 g) and shell wet weight (13.6 g) were significantly increased (P < 0.05). Water quality parameters including the water temperature ($22.1{\pm}0.4^{\circ}C$), salinity ($24.9{\pm}04$), dissolved oxygen (5.1-7.9 mg/L) and pH ($7.93{\pm}0.15$) were kept stable. Concentration of dissolved inorganic nutrient as ammonia (1.96-0.35 mg/L), nitrite (0.03-0.16 mg/L), nitrate (1.34-0.47 mg/L), DIP (0.42-0.03 mg/L) and silicate (3.83-0.00 mg/L) were significantly decreased throughout experiment except nitrite which was increased (P < 0.05), but nitrogenous components stayed below toxic levels (ammonia 0.0-5.5 mg/L, nitrite 0.0-460.0 mg/L) which indicated that closed recirculation system with microalgae based bio-filter could supply sufficiently environment condition to holding and conditioning of oyster.

• Journal of Aquaculture
• /
• v.9 no.3
• /
• pp.223-232
• /
• 1996

Growth and survival rate in shortnecked clam, Ruditapes philippinarum were studied from different seedling production areas, Hadong, Ulsan and Kochang to Kwangyang Bay, Korea, and three stocking densities (1,000, 1,500 and 3,000 individuals/$m^2$) of clam from Ulsan seedling production area were examined. During the experimental period, water temperature and specific gravity were ranged from 4.5 to $26.0^{\circ}C$ and from 1.0216 to 1.0248, respectively. Shell length was grown from $2.30{\pm}0.05\;to\;3,29{\pm}0.02$ cm in Hadong, $1.32{\pm}0.02\;to\;3.15{\pm}2.02$ cm in Ulsan, $1.24{\pm}0.03\;to\;3.18{\pm}0.02$ cm in Kochang. Kochang's seed was displayed fast growth rate than others. In different rearing densities, the lower density group was showed a rapid growth rate. Shell length from the 1,000 individuals per $m^2$ group grew longer than that from the 2,000 individuals group. Total weight from the 1,000 individuals group was higher than that from the 1,5()0 individual and the 2,000 individual groups. Survival rate by seedling production areas, Hadong, Ulsan and Kochang showed $69.4\%,\;63.8\%\;and\;41.7\%$, respectively. Survival rate by rearing density, 1,000, 1,500 and 2,000 individual groups showed $70.8\%,\;67.8\%\;and\;59.0\%$, respectively.

• The Korean Journal of Malacology
• /
• v.27 no.4
• /
• pp.353-358
• /
• 2011

This study is the result of examining the growth and survival rate of larva and spat when supplied with Enriched live food by adding $B_{12}$, chitosan, PSB, and polysaccharides to microalgae (Chaetoceros gracilis, Isochrysis galbana) to raise the survival rate of larva and spat during artificial clam seed production. Microalge (Chaetoceros gracilis, Isochrysis galbana) was strengthened for nutrition with $B_{12}$ 0.1 ppm, chitosan 0.2 ppm, PSB 3 ppm and polysaccharides 1 ppm and was daily supplied for $3{\times}10^3-15{\times}10^3Cells/mL$ and the growth and survival rates were measured. As the result of experiment, the growth of larva did not show much difference with PSB test section $199{\pm}0.59{\mu}m$, $B_{12}$ test section $198{\pm}0.64{\mu}m$, and chitosan $197{\pm}0.52{\mu}m$, survival rate was highest at PSB test section with 99.3%, followed by $B_{12}$ test section 95.9%, and chitosan 94.5%. Growth of early spat was the highest for PSB test section at $2.74{\pm}0.58mm$, followed by polysaccharides $2.67{\pm}0.55mm$, $B_{12}$ $2.54{\pm}0.48mm$, and chitosan $2.49{\pm}0.51mm$, and the survival rate was the highest for PSB test group at 32.1%, followed by $B_{12}$ test section 31.6%, chitosan 28.5%, and polysacharrides 21.4%. From such results, PSB is found to be very effective with low-quality improvement when breeding early spat of clams, and especially for floor-type early spat breeding, it had the effect of suppressing protozoan and germs so that detailed studies from various perspectives should be conducted with various chemicals in the future.