• Journal of Korean Society of Forest Science
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• v.109 no.4
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• pp.492-503
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• 2020

This study was conducted to analyze stem decay in Quercus mongolica and Quercus variabilis in Korea. To ensure even allocation, a total of 5,005 sample trees (2,504 Q. mongolica and 2,501 Q. variabilis) were cut and collected in five regions and 27 subregions. The trees were then examined for stump decay and assigned to four classes based on the degree of scar, tissue decay and decolorization, splitting, and tree hollowing. The results show that the decay rate of Q. mongolica was 66.1%, at least twice as high as that of Q. variabilis, which was rated at 35% (χ2 = 631.15, p < 0.001). The comparison among regions indicated that the highest ratio of Q. mongolica occurs in the Central Regional Forest Service zone (76.5%), followed by the Northern zone (74.8%) and Eastern zone (65.7%). In contrast, the greatest proportion of Q. variabilis is found in the Northern Regional Forest Service zone (38.6%), followed by the Southern (32.9%) and Eastern (37.8%) zones. A statistically significant difference was seen among the five zones (p < 0.05, p < 0.001). There was also a clear tendency for the proportions for the two species to increase with a rise in the DBH. With respect to age, however, a statistically significant difference was found (p < 0.01, p < 0.05) only in Q. mongolica, whose rate increased with the increase in age. Our results show that as the DBH and age increases, the conditions of tissue decay and decolorization are manifested in Q. mongolica, whereas scars are common in Q. variabilis.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.11
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• pp.751-756
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• 2012

In this study, a heavy-metal stabilization treatment using stabilizing agents derived from waste resources was utilized on Incheon North Port range sediment contaminated with Pb, Zn, and Cu. Both calcined red mud (5%, 10%, and 15% w/w) and oyster shell (5%, 10%, and 15% w/w) were applied for a wet-curing duration of 15 days. From the sequential extraction results, the oxide and organic fraction of heavy metals (Pb, Zn, and Cu) were observed strongly in the contaminated sediment. However, the fraction of heavy metal in the stabilized sediment was higher than the organic and residual fraction, in comparison to the contaminated sediment. Moreover, the leaching of heavy metals was reduced in the stabilized sediment, compared with the contaminated sediment. From these results, red mud and oyster shell were shown to be potential stabilizers of heavy metals in contaminated sediment.

• 월간산업보건
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• no.8 s.244
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• pp.58-59
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• 2008

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.219-226
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• 2020

Over the last decades, great efforts have been devoted to reuse industrial wastes and by-products from various industries as supplementary cementitious materials in order to reduce carbon dioxide(CO₂) emission by reducing the use of Portland cement in construction. Oyster shell waste, originating from the fishery industry, is available in huge quantities in certain areas, and is generally discarded or landfilled. In this study, we aimed to reuse oyster shell as an alternative to limestone in limestone calcined clay cement(LC³). The oyster shell calcined clay cement(OC³) paste were produced and were characterized via X-ray diffraction, isothermal calorimetry, compressive strength tests, and thermogravimetry. The results revealed that OC³ pastes exhibited similar strength development and reactivities by pozzolanic reaction with LC³, which implies that oyster shell could be used as a substitute for limestone in LC³.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.146-147
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• 2013

The oyster shells of about 240,000 tons have been annually produced in south coast of South Korea. However, about 25% of the oyster shells (60,000tons) was recycled as oyster seeding and fertilizer due to the limited amount of consumption for such purposes. The stored amount of oyster shell in the fertilizer manufacturing company is overfilled, and thus cannot accept any more of the waste oyster shells. As a result, landfill and illegal dumping of waste oyster shells have become an increasingly serious issue since 2011. In this research, the problems generated by the oyster shells were investigated through surveying activities. One of the possible alternative solutions that can process large amount of waste economically was found to be the application of oyster shells as a construction materials.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.4
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• pp.634-639
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• 1997

In order to obtain the basic knowledges for the effective seed production of Perinereis aibuhitensis, sediment preference, burrow shape and behavior with in burrow were investigated in the laboratory. The highest value in both sediment preference and survival rate of P. aibuhitensis were shown at fine sand below 0.10 mm in the mean diameter. The worm made various types of burrows, such as J, L, O, Y and I shapes. Generally, only one individual inhabits in a burrow with head-up, but when excreting, it positions up-side down.

• The Korean Journal of Malacology
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• v.28 no.1
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• pp.45-54
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• 2012

We investigated environmental characteristics of the tidal flat oyster aquafarms to clarifyeffects of the tidal flat environmental factors on growth and mortality of the tidal flat oyster Crassostrea gigas by the Net Bag Rack Culture System in two districts in Western Korea. In this study, we have carried out the basic environmental investigation on growth of the single tidal flat, water quality and sediments, etc. in Taean and Seosan districts, Choongcheongnam-do, where the single tidal flat oyster aquaculture have been performed by the net bag rack culture system. In June 2011 when the final survey carried out at the two districts in western Korea, the mortality in Seosan district was higher than that in Tae-an district. Judging from the results of growth and mortality of the single tidal flat oysters investigated at two sites of Jinsan-ri in Taean and Chang-ri in Seosan districts, two results of Taean district showed higher growth and lower mortality than those of Seosan district. It is assumed that the proper acceptable density possible for growth of the tidal flat seeds and the secure of economics, in case of plastic cultivate net with the size of $50{\times}80cm$, are about 200 individuals. In this study, It was clarified that selection of the suitable sites, the input into the net bag of high quality oyster seeds and selective dispersion in the optimal density of the single tidal flat oyster have an effect on growth and mortality of the tidal flat oyster.

• Journal of agriculture & life science
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• v.53 no.6
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• pp.109-118
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• 2019

Effects of hybrid decompressor heat pump dryer in processing and storage stability of oysters was investigated. Dried oyster samples were stored at -20℃ for eight weeks and changes in physicochemical characteristics, nutritional and microbial content, and bioactivity were evaluated. Total aerobic plate count in dried oyster samples (L1-1, L1-3, and R2-2), after storage, were found safer at 18~19×10³ CFU/g than that of commercial (CD-1) products at 27~30×10³ CFU/g. DHA levels were higher in L1-1, L1-3, and R2-2 (17.87%, 17.46%, 17.89%, respectively) than in CD-1 (15.41%). Meanwhile EPA levels (13.20~16.87%) and total free amino acids (1325.2~1260.4 mg/100g) slightly varied among samples. K-values were found highest in CD-1 (34~42.1%) sample which indicated great decrease in freshness.

• Journal of the Korea Institute of Building Construction
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• v.16 no.3
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• pp.193-199
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• 2016

This study is a research about performance of fireproof board using industrial waste such as oyster shell and dry process bottom ash through the heating test and conclusions were obtained as follows. Test samples show back side temperatures as follows : in $300^{\circ}C$, $103.1{\sim}125.1^{\circ}C$, in $600^{\circ}C$, $201.1{\sim}210.1^{\circ}C$, in $900^{\circ}C$, $249.2{\sim}276.9^{\circ}C$. In the test, temperature increases of specimens of fireproof board are kept at certain temperatures hence it could be concluded that the specimens withstand high temperatures. According to the test, it could be concluded that fireproof board made by smaller particles shows better performance up to $600^{\circ}C$ while at higher temperatures, fireproof board made by bigger particles shows better performance. It is estimated that fireproof board made by particles of bigger size has more pore structure and it delays heat conduction.

• Journal of the Speleological Society of Korea
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• no.53
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• pp.15-24
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• 1998

여가 및 레저에 대한 의식구조의 변화와 가족 중심의 여가활동의 비중이 증가하면서 자연학습장으로서, 지구과학 전시관으로서의 역할을 하고 있는 동굴이 이동을 전제로 한 가족 단위 관광객들의 관광 대상지로서 주목받고 있다. 이에 본 연구에서는 관광자원으로서의 동굴의 특성을 살펴보고, 그 중에서도 개발 역사가 오랜 성류굴의 관광적 특성을 살펴보았다. 그 결과는 다음과 같다. 동굴은 지형 ·지질작용과 관계가 깊은 자원이지만 지하의 신비적 경관이 관광자원으로 활용되고, 그 구조의 특성에 따라 산업적 ·군사적 또는 학술적 연구의 이용에 크게 기여하는 등 다기능적 복합성을 띠고 있기 때문에 본 연구에서는 동굴을 ‘복합 관광자원’이라 분류한다. 이런 동굴 중에서 성류굴은 오랜 역사를 지닌 관광자원으로서 구전 전설의 주인공이라는 ‘문화 · 역사적인 특성’, 다양한 볼거리를 제공하는 ‘지형적인 특성’, 도로와 철도를 이용한 ‘교통접근성’ 등의 관광적 특성을 지니고 있다.