• 방사성폐기물학회지
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• 제20권3호
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• pp.297-306
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• 2022

The acoustic emission (AE) is proposed as a feasible method for the real-time monitoring of the structural damage evolution in concrete materials that are typically used in the storage of nuclear wastes. However, the characteristics of AE signals emitted from concrete structures subjected to various environmental conditions are poorly identified. Therefore, this study examines the AE characteristics of the concrete structures during uniaxial compression, where the storage temperature and immersion conditions of the concrete specimens varied from 15℃ to 75℃ and from completely dry to water-immersion, respectively. Compared with the dry specimens, the water-immersed specimens exhibited significantly reduced uniaxial compressive strengths by approximately 26%, total AE energy by approximately 90%, and max RA value by approximately 70%. As the treatment temperature increased, the strength and AE parameters, such as AE count, AE energy, and RA value, of the dry specimens increased; however, the temperature effect was only minimal for the immersed specimens. This study suggests that the AE technique can capture the mechanical damage evolution of concrete materials, but their AE characteristics can vary with respect to the storage conditions.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.889-901
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• 2021

The tension of cables and motion response significantly affect safety of an immersed tunnel element in the immersion process. To investigate those, a hydrodynamic scale-model test was carried out and the model experiments was conducted under wind, current and wave loads simultaneously. The immersion standby (the process that the position of the immersed tunnel element should be located before the immersion process) and immersion process conditions have been conducted and illustrated. At the immersion standby conditions, the maximum force of the cables and motion is much larger at the side of incoming wind, wave and current, the maximum force of Element-6 (6 cables directly tie on the element) is larger than for Pontoon-8 (8 cables tie on pontoon of the element), and the flexible connection can reduce the maximum force of the mooring cables and motion of element (i.e. sway is expecting to decrease approximate 40%). The maximum force of the mooring cables increases with the increase of current speed, wave height, and water depth. The motion of immersed tunnel element increases with increase of wave height and water depth, and the current speed had little effect on it. At the immersion process condition, the maximum force of the cables decrease with the increase of immersion depth, and dramatically increase with the increase of wave height (i.e. the tension of cable F4 of pontoons at wave height of 1.5 m (83.3t) is approximately four times that at wave height of 0.8 m). The current speed has no much effect on the maximum force of the cables. The weight has little effect on the maximum force of the mooring cables, and the maximum force of hoisting cables increase with the increase of weight. The maximum value of six-freedom motion amplitude of the immersed tunnel element decreases with the increase of immersion depth, increase with the increase of current speed and wave height (i.e. the roll motion at wave height of 1.5 m is two times that at wave height of 0.8 m). The weight has little effect on the maximum motion amplitude of the immersed tunnel element. The results are significant for the immersion safety of element in engineering practical construction process.

• 한국식품과학회지
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• 제22권5호
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• pp.497-502
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• 1990

삼투압 농축중 설탕용액의 농도와 온도 및 침지시간에 따른 감자 내부의 수분손실, 고형분 증가나 손실 및 몰랄농도를 반응 표면 분석법으로 조사하였고, 이차 다항 회귀 모델로써 예측하였다. 또한 삼투압 농축과 데치기가 6%수분(wet basis)까지 열풍조건시 비타민 C 함량유지에 미치는 효과를 평가하였다. 감자내부의 수분손실, 고형분 증가나 손실, 몰랄농도, 속도 매개변수 및 비타민 C 함량에 가장 크게 영향을 미치는 요소는 설탕농도이었고 그 다음 침지시간과 침지온도 순이었다. 수분손실과 설탕흡수는 초기 10분간 침지과정에서 빠르게 이루어진 후 증가현상이 둔화되었다. 설탕용액 $(60\;Brix,\;80^{\circ}C)$에서 20분간 침지 후 44.6%의 수분손실이 되었다. 삼투압 농축후 건조시킨 감자가 데치기 한 후 건조시킨 감자보다 높은 비타민 C 함량을 유지하였다. 30% 이상의 수분손실과 50% 이상의 비타민 C 함량유지의 관점에서 삼투압농축공정의 최적조건은 $60-70^{\circ}C$의 침지온도와 60 Brix의 설탕농도 및 16-20분간의 침지시간이었다.

• 한국식품과학회지
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• 제34권3호
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• pp.413-418
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• 2002

제빵에 이용 할 반죽을 발효하거나 발효하지 않은 상태로 다섯 가지의 다른 냉동 및 저장 환경에서 냉동하고 일주일간 저장하여 해동 한 후 제조된 빵의 품질을 비교하였다. 냉동속도가 빠르더라도 발효한 후 냉동된 반죽은 빵의 부피가 감소하였으며 이러한 문제점은 침지식 냉동 방식에서도 해결되지 않았다. $-70^{\circ}C$의 초저온 냉동은 $-20^{\circ}C$ 침지식 냉동고에 비하여 냉동 온도가 매우 낮으나, 냉동 속도도 느리고 해동 후 재 발효하여도 빵의 부피가 작아서 효과적인 냉동 방법이 되지 못하였다. 반면 냉동 속도는 느리지만 $-20^{\circ}C$ 공기 송풍식 냉동고가 $-70^{\circ}C$ 공시 송풍식 냉동고보다 냉동에 따른 장해가 적어서 반죽의 발효가 잘되었다. 동일한 온도일 때는 침지식 냉동이 더욱 효과적이었으며 침지식 가운데도 온도가 더 높은 $-10^{\circ}C$ 냉동이 가장 효과적이어서 발효하지 않고 냉동하여 재 발효 할 경우 대조구보다도 오히려 반죽의 발효가 잘되어 빵의 부피가 더 컸다. 따라서 본 연구에 이용한 방법 가운데 $-70^{\circ}C$ 공기 송풍식 냉동고에서 냉동, 저장하는 것이 가장 비효율적이며 침지식 냉동방법들이 냉동 온도가 높더라도 오히려 해동 후 발효 장해가 적어서 효율적이었다. 위의 실험 결과를 종합하였을 때, 냉동 전에 반죽을 발효하지 않고 $-10^{\circ}C$ 침지식 냉동고에서 냉동하여 저장하거나, $-20^{\circ}C$ 침지식 냉동고에서 초기에 냉동을 하고, $-20^{\circ}C$ air freezer에 저장하는 방법이 가장 효과적이었다.

• 한국어병학회지
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• 제35권2호
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• pp.225-230
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• 2022

Viral hemorrhagic septicemia (VHS) is one of the most serious viral diseases affecting farmed olive flounder (Paralichthys olivaceus) in Asian countries. VHS, caused by viral hemorrhagic septicemia virus (VHSV), occurs in over 80 different cultured and wild fish species worldwide. Our previous study demonstrated that VHSV infection can be restricted by adjusting the water temperature to over 17℃ from the host optima. We confirmed that the effective VHSV immersion vaccine treatment was a tissue culture infection dose (TCID) of 10^5.5 TCID₅₀/mL at 17℃. However, the safety of live VHSV immersion vaccines remains unclear. The objectives of this study were to 1) demonstrate the safety of the live VHSV immersion vaccine under co-habitant conditions and 2) estimate the pathogenicity of VHSV in live VHSV-vaccinated flounder at 10℃. No mortality was observed in olive flounder treated with the live VHSV immersion vaccine, and the vaccinated flounder challenged with VHSV did not transfer VHSV to naïve fish at 10℃ through cohabitation. VHSV titration was below the detection limit (< 1.3 log TCID₅₀/mL) in live VHSV immersion vaccine-treated flounder challenged with VHSV at 10℃. This study demonstrated that flounder treated with the live VHSV immersion vaccine were resistant to VHSV infection, and the live vaccine was also safe for naïve fish even at a water temperature known to be VHS infectious.

• Fisheries and Aquatic Sciences
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• 제8권1호
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• pp.10-16
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• 2005

Conditions for sufficient and rapid distribution of a cryoprotectant (sorbitol solution) into intact fish muscle (Oncorhynchus mykiss) were studied as changing in the residual Ca2+ ATPase activity during freeze/thaw cycling. Chunks of the fish muscle were immersed in 4 concentrations of sorbitol solutions ($20\%$, $30\%$, $45\%$, and $60\%$) by a shaker mechanism at 5$^${circ}C. Whole immersion samples (W) showed a higher value of the residual Ca2+ ATPase activity than those in the untreated controls (C), except in the treated controls (TC), while less effect of immersion concentration could be found. Comparing the extent of penetration of sorbitol into the surface layer to inner layer of immersed fish chunks, outer portion samples achieved excellent cryoprotection with $100\%$ of the residual ATPase activity values or more. For the inner portion samples, $30\%$ and $45\%$ sorbitol solution treatments indicated a higher ATPase activity than $60\%$ treatment. At high concentrations, mass transfer rates during osmotic dehydration might berapid and it causes faster surface drying by dewatering at surface solute layer. Periodically immersed and relaxed samples, W (5-3-1), led to good cryoprotection effect: W (5-3-1) indicated high residual Ca2+ ATPase activity values and the residual ATPase activity values excess $100\%$ in immersion of $30\%$ and $45\%$ sorbitol solutions.

• 한국지하수토양환경학회지:지하수토양환경
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• 제25권4호
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• pp.58-66
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• 2020

Since the typical horn-type ultrasonic equipment induces a reaction at the probe tip, the sonochemical reaction has a limitation that it occurs only in a specific area. As one of the ways to overcome this limitation, an ultrasonic device with multi-stepped horn equipped with several oscillators has been developed. The objective of this study was to investigate the sonochemical effects induced by acoustic cavitation system in 20 kHz multi-stepped ultrasonic horn using calorimetry, KI dosimetry and the luminol test. The sonochemical effects of multi-stepped ultrasonic horn were compared with that of the typical horn-type 20 kHz ultrasonic device. The effect of immersion depth and power on the sonochemical reaction was investigated in the ultrasonic system with multi-stepped ultrasonic horn. Higher calorimetric energy was obtained at higher immersion depth and power conditions. Sonochemical effects increased significantly when using the high immersion depth and input power. However, as the input power increased, the cavitation reaction zone concentrated around the ultrasonic horn. Additionally, the experiments to examine the effect of liquid temperature was conducted. The smaller sonochemical reaction was obtained for the higher liquid temperature. The effect on temperature seems to be closely related to liquid conditions such as viscosity and vapor pressure of water.

• Corrosion Science and Technology
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• 제21권2호
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• pp.158-169
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• 2022

The objective of this study was to investigate the electrochemical behavior and damage degree of metal surface under different conditions by performing a potentiodynamic polarization experiment using an electropolishing solution for UNS S31603 based on initial delay time and surface roughness (parameters). A second anodic peak occurred at initial delay time of 0s and 100s. However, it was not discovered at 1000s and 3600s. This research referred to an increase in current density due to hydrogen oxidation reaction among various hypotheses for the second anodic peak. After the experiment, both critical current density and corrosion current density decreased when the initial delay time (immersion time) was longer. As a result of surface analysis, characteristics of the potentiodynamic polarization behavior were similar with roughness, although the degree of damage was clearly different. With an increase in surface roughness value, the degree of surface damage was precisely observed. As such, electrochemical properties were different according to the immersion time in the electropolishing solution. To select electropolishing conditions such as applied current density, voltage, and immersion time, 1000s for initial delay time on the potentiodynamic polarization behavior was the most appropriate in this experiment.

• Korean Journal of Mathematics
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• 제17권1호
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• pp.1-13
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• 2009

For an isometric immersion $f:M{\rightarrow}{\bar{M}}$ of Finsler manifolds M into $\bar{M}$, we compare the intrinsic Chern connection on M and the induced connection on M: We find the conditions for them to coincide and generalize the equations of Gauss, Ricci and Codazzi to Finsler submanifolds. In case the ambient space is a locally Minkowskian Finsler manifold, we simplify the above equations.

• 한국염색가공학회지
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• 제5권2호
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• pp.144-148
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• 1993

To increase the moisture content and thereby to reduce the static charge of polyacrylonitrile (PAN), thin layer surface photografting of acylamide (AAm) onto PAN fabrics by using benzophenone as a initiator with a mixtured solvent was carried. The effects of reaction conditions such as monomer, initiator concentrations, UV irradiation time and immersion time of fabrics on grafting were investigated. The percent grafting slightly increased with increasing monomer concentration, benzophenone concentration up to limiting value and thereafter decreased or level offed. The percent grafting was significantly increased with increasing irradiation and immersion times. The moisture regain increased with increasing the percent grafting. The static charge decreased with increasing the percent grafting.