• Journal of Fisheries and Marine Sciences Education
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• v.28 no.4
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• pp.1098-1106
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• 2016

To study the influence of light intensity on blind-side hypermelanosis of starry flounder, Platichthys stellatus, we compared growth, glucose, cortisol, ratio of malpigmented blind-side area, ambicolored fish ratio and expression of mch mRNA for 60 days in 0 lux(darkness) and 20 lux(low light density). The test was done in duplicate at 50 fish/tank with the selected ordinary juvenile flounder. The rearing was performed in FRP aquarium tanks ($H100cm{\times}L100cm{\times}W100cm$). Growth was higher in the 0 lux. The ratio of malpigmented blind-side area and ambicolored fish ratio were significantly higher at the 0 lux than at the 20 lux. The result suggests that 20 lux could inhibit the hypermelanosis. The expression level of MCH 1, 2 mRNA was significantly lower in 0 lux, indicating that MCH 1, 2 and light intensity are related to blind-side hypermelanosis of starry flounder.

• Journal of Fisheries and Marine Sciences Education
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• v.19 no.1
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• pp.84-90
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• 2007

This paper was studied on the electrochemical corrosion characteristics of weld zone for refrigerating and heating systems pipe. Austenitic stainless steel is widely applied to various fields of industry, because it is good to corrosion resistance and mechanical properties. But STS 304 is reliable to sensitization by heat cycle on welding. Therefore, in this study, electrochemical polarization test of STS 304 steel pipe manufactured by arc welding in tap water was carried out. And then polarization resistance behavior, uniform and local corrosion behaviors of base metal(BM), weld metal(WM) and heat affected zone(HAZ) for STS 304 pipe were investigated. The corrosion current density of STS 304 steel pipe is high in order of BM(153nA/cm2) < WM(614nA/cm2) < HAZ ($1.675{\mu}A/cm2$). The pitting potential of HAZ(238mV/SCE) for STS 304 is lower than BM(1206mV/SCE) and WM(369mV/SCE). Therefore, the local corrosion like pitting corrosion, galvanic corrosion and crevice corrosion of HAZ for STS 304 is more sensitive than BM and WM.

• Journal of Korea Foundry Society
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• v.22 no.3
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• pp.137-143
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• 2002

Silica sand, zircon sand, and steel shots were used as mold packing materials in lost foam casting of the aluminum alloy bar. Vibration acceleration in three directions and temperatures in the casting and mold were measured, and packing and cooling characteristics of these materials were investigated. Packing densities increased with increase in vibration magnitude and time, and were $1.41{\sim}1.49g/cm^2$ for silica sand, $2.54{\sim}2.86g/cm^2$ for zircon sand, and $3.92{\sim}4.52g/cm^2$ for steel shots. Sound castings were obtained only without evacuation of the flask during pouring. Solidification time became faster in order of silica sand, zircon sand and steel shot packing because steel shot has the highest cooling capacity of them. Solidification time of steel shot packing was shortened to about 1/2 of silica sand packing. Cooling capacity of sand mold was generally evaluated by heat diffusivity of the mold, however could be simply evaluated with specific heat per unit volume of the packing material in lost foam casting.

• Bulletin of the Korean Chemical Society
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• v.15 no.12
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• pp.1042-1045
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• 1994

A thin film of silver ferricyanide (Ag$_3$Fe(CN)$_6$) on a platinum or gold substrates can be reduced electrochemically to the salt of silver ferrocyanide in potassium nitrate solution. The color of these films are orange and these films are shown to be electrochromic. The voltammogram is shown the asymmetry of the oxidation compared to the reduction wave under various supporting electrolytes. The standard heterogeneous electron-transfer rate for these films and bare Pt electrode were 0.49 ${\times}$ l0$^{-2}$ and 1.30 ${\times}$ l0$^{-2}$ cm/s, respectively, obtained using a rotating disc electrode. Rough D$_0$ values, evaluated from the Levich equation, for Fe(CN)$_6^{3-/4-}$ at both SF thin film and a bare Pt disc electrode were shown as 1.2l ${\times}$ l0-6 and 0.94 ${\times}$ l0$^{-6}$ cm$^2$/s, respectively. The conductivities, as determined from the slops of the i-V curves for a ca. 1 mm sample for dried SF potassium rich and deficient bulk samples pressed between graphite electrodes, were 9.34 ${\times}$ l0$^{-9}$ and 5.80 ${\times}$ l0$^{-9}$ (${\Omega}$${\cdot}$cm)$^{-1}$, respectively.

• Journal of radiological science and technology
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• v.44 no.5
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• pp.451-457
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• 2021

Recently, the number of interventional procedures has increased dramatically as an alternative of invasive surgical procedure and patient radiation exposure is also increasing accordingly. In this study, we evaluated the patient dose of major interventional procedures nationwide and we established our Korean database. With these results, we tried to suggest the reference dose level for major interventional procedures. We evaluated patent dose data in the field of interventional radiology from foreign countries. Measurement of radiation dose exposure for 11 major interventional procedures was conducted using embedded DAP meters in 10,006 patients from 47 hospitals, and reference level of each interventional procedure was suggested. The DRLs of each intervenional procedure are as follows: TACE 206(Gy·cm²), AVF 12(Gy·cm²), LE intervention 43(Gy·cm²), TFCA 122(Gy·cm²), Cerebral aneurysm coil embolization 214(Gy·cm²), PTBD 22(Gy·cm²), Biliary stent 60(Gy·cm²), PCN 7(Gy·cm²), Hickman catheter 2.1(Gy·cm²), Chemoport 1.4(Gy·cm²), BAE 104(Gy·cm²). Compared with the previously established DRL in 2012, the radiation dose decreased in all 10 interventional procedures. In the future, continuous publicity and education on the radiation dose reduction will be needed.

• The Korean Journal of Ecology
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• v.7 no.4
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• pp.185-193
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• 1984

Regneration process of Abies koreana-Pinus koraiensis community consisted of a subalpione coniferous forest in Mt. Jiri, Korea, was studied in relation to age structure, especially to gap formation. The tall-tree layer (ca. 6.5m) is dominated by Abies koreana and Pinus koraiensis, while lower layer by the sapling and juveniles of A. koreana and Picea jezoensis below 2m tall. The ranges of DBH in A. koreana, P. koraiensis and P. jezonesis were 11.8cm~26.4m, 11.7cm~24.5 cm and 18.2cm~21.7 cm, respectively. The trees below 130 cm tall had contagious distribution, while tall and subtall trees had uniform distribution. The average tree ages of A. koreana, P. koraieniensis and P. jezoensis were 60~70 years, 70~80 years and 70~90 years, respectively. The saplings and juveniles below 20 years in tree ages were occupied over 80% of total trees. The coniferous trees in the gaps or around dead trees were composed of sapligs and juveniles which had emerged or invaded about 20 years before and after the gap formation. The Betula type regeneration of the coniferous forest took place in gaps which orginated from the failing down of a single or a few trees by longevity. Accordingly, it is clear that the subalpine coniferous forest composed of A. koreana of A. koreana, P. koraiensis and P. jezoensis in Mt. jiri was supporting by the regeneration pattern of Betula type.

• Geomechanics and Engineering
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• v.13 no.3
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• pp.431-446
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• 2017

Rock bridges in rock masses would increase the bearing capacity of Non-persistent discontinuities. In this paper the effect of ratio of rock bridge surface to joint surface, rock bridge shape and normal load on failure behaviour of intermittent rock joint were investigated. A total of 42 various models with dimensions of $15cm{\times}15cm{\times}15cm$ of plaster specimens were fabricated simulating the open joints possessing rock bridge. The introduced rock bridges have various continuities in shear surface. The area of the rock bridge was $45cm^2$ and $90cm^2$ out of the total fixed area of $225cm^2$ respectively. The fabricated specimens were subjected to shear tests under normal loads of 0.5 MPa, 2 MPa and 4 MPa in order to investigate the shear mechanism of rock bridge. The results indicated that the failure pattern and the failure mechanism were affected by two parameters; i.e., the ratio of joint surface to rock bridge surface and normal load. So that increasing in joint area in front of the rock bridge changes the shear failure mode to tensile failure mode. Also the tensile failure change to shear failure by increasing the normal load.

• Journal of Wetlands Research
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• v.15 no.1
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• pp.25-34
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• 2013

The purpose of this study is to investigate the properties of Menyanthes trifoliata habitat in coastal lagoons. To characterize plant composition in the habitats in the lagoon, the plot sampling method was applied. The depths of water and floating mat were measured. Surface water quality factors including pH, electrical conductivity (EC), dissolved oxygen (DO), and total dissolved solids (TDS) were measured in the sites. Phosphate, nitrate, ammonium, and major cations were measured in laboratory. The wetland has 78 taxa of wetland plants. The average coverage and density of M. trifoliata was 62.6% and $71.2/m^2$, respectively and Phragmites australis is important associate in Sunyoodam lagoon. The average depths of floating mats were 26.5cm in M. trifoliata and 68.9cm in the P. australis-M. trifoliata communities, and the water depth below the mat was 106.5cm and 17.7cm, respectively. The values of pH, DO, EC and TDS in the water were 5.06, 46.1%, 59.4 ${\mu}s/cm$, and 29.3 mg/L, respectively. The concentrations of phosphate, nitrate, and ammonium showed 47.2, 9321, and 15.9 ${\mu}g/L$, respectively. The concentrations of Ca, K, Na, and Mg had 11.1, 1.5, 15.1, and 11.3 mg/L, respectively. The habitats of M. trifoliata in the lagoon corresponds to a kind of lowland communities in Hewett's classification. To conserve the habitats of M. trifoliata in Sunyoodam lagoon, the supply of open water area, the construction of observation deck, and the block of inflow from the surrounding paddy fields are needed in the future.

• Journal of Digital Contents Society
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• v.4 no.1
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• pp.23-34
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• 2003

The number of internet users rapidly increases, it has development of various learning method and education-contents. Currently, it has increasing of management, maintenance and reusing of education-contents through CMS (Content Management System) and SCORM(Shareable Content Object Reference Model) standard but actually, it has not more service for customer, In this paper, we propose CMS(Content Management System) using the supporting self learning method for increasing teaming effective of customer.

• Korean Journal of Health Education and Promotion
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• v.11 no.2
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• pp.160-175
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• 1994

년대별로 본 한국인의 성장발육상태를 서로 비교해 봄으로서 얼마나 향상되었나 알아보고자 1910년도부터 1994년까지 각 저자들의 성적을 조사분석한 바 다음과 같은 결론을 얻었다. 1. 신체계측치인 신장, 체중, 흉위, 좌고는 가령에 따라 증가하고 있으나 성장 완료기에서는 각년도별로 점차 증가되었고 특히 1960년 이후 1994년에서는 그 성장이 현저하게 나타났다. 2. 신장과 체중은 평균 10년당 남자의 경우 1.3cm와 1.3kg씩 증가되었으며 여자는 1.6cm와 0.94kg씩 증가하였다(상기의 수치들은 평균증가치임). 3. 성장완료기에 있어서 각 년도별로 성장발육이 증가되었고 특히 1967년, 1983년, 1985년 그리고 1994년에 와서는 현저한 증가를 나타내었다. 이러한 현상은 사회적 경제적 제조건의 향상으로 한국인의 식생활이 좋아졌음으로 성장발육과 체위향상에 많은 영향을 미쳤다는 것을 입증하고 있다.