• Journal of IKEEE
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• v.24 no.1
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• pp.260-268
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• 2020

This paper presents the high frequency resonant inverter of class D SEPP(Single-Ended Push Pull) type using LS-ZVS-LSTC, which can reduce the switching losses during the turn-on and turn-off switching time. The analysis of high frequency resonant inverter using LS-ZVS-LSTC(Low-loss Turn-off Snubber Capacitor) proposed in this paper is described in general by adopting the normalized parameters. The operating characteristics of the proposed high frequency resonant inverter were also evaluated by using the control parameters such as the normalized control frequency(μ), the normalized load time constant(τ), the coupling factor(κ) and so on. Based on the characteristic values through the characteristics of evaluation, an example of the design method of the 1.8[kW] class D SEPP type high frequency inverter is suggested, and the validity of the theoretical analysis is verified using the experimental data.

• Journal of Soil and Groundwater Environment
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• v.26 no.1
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• pp.24-33
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• 2021

Analysis of long term affecting factors on water quality items of gas emission form (BOD, COD) and leachate emission form (T-N, non-bio-degradable COD (NBDCOD)) was performed for the SUDOKWON 1st Landfill Site (LS1) and 2nd Landfill Site (LS2). As landfill gas was generated, BOD and COD decreased from 6,887 and 20,025 mg/L in 1993 to 49.5 and 670.2 mg/L in 2019, respectively. TN and NBDCOD increased with waste decomposition but gradually decreased after landfill closure because of the precipitation infiltration effect. Due to the drastic decline of carbon in the leachate, the BOD/TN ratios of LS1 and LS2 declined from 13.0 and 17.0 during early stage of the landfill to 0.07 and 0.16 in 2019, respectively; LS2 and NBDCOD/COD increased from 0.25 to 0.65 during the same period. These conditions caused carbon deficiency in denitrification treatment and a chemical post-treatment request for NBDCOD. The different behaviors of gas emission and leachate emission items suggest the necessity of different strategic approaches in the long term perspective.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.81-82
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• 2013

HVDC 시스템은 초고압 직류 송전 시스템으로써, AC를 DC로 변환하여 장거리 송전에 유리한 시스템이다. 현재 대륙간 송전 및 주파수 변환을 위한 BtB Topology에 많이 응용되고 있다. HVDC 시스템의 장점은 일정 송전거리 이상이 되면, DC가 AC에 비하여 손실율이 적고 유리한 장점이 있다. 해당 HVDC Valve는 전력을 AC-DC-AC로 변환하려면, HVDC Valve(Module)이라고 불리는 전력 변환 장치가 필수적이다. 해당 Valve를 현장에 설치하기 전에 IEC 60700-1 또는 CIGRE 같은 국제 표준 규격에 맞추어 Type Test를 진행 후에 통과 시 현장에 설치되어야 한다. 해당 Type Test는 크게 2가지로 분류되며, 절연 성능을 시험하기위한 Dielectric Test 그리고, 실제 Thyristor Valve의 동작을 가혹 한 조건에서 시험하기위한 Operational Test가 필요하다. 본 논문은 IEC 규격 (IEC 60700-1)에 의거 사이리스터 밸브에 대한 Operational Test 중 단락시험방법과 시험내용을 기술하고, 시험결과로 검증한다.

• Journal of the Korean Wood Science and Technology
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• v.22 no.2
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• pp.54-60
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• 1994

The pine bark from mechanical pulp industry was cooked with bisulfite liquor, and the chemical and physical properties of the spent liquor after cooking for 90 minutes, which allowed partial defibration were determined. Lignosulfonate or lignin-related materials in the spent liquor have a molecular weight of approximately 3,000, which is lower than that of commercial lignosulfonate (C-LS) prepared from wood. The sulfonic equivalent weight calculated by colloid titration was 307 for C-LS, 238~239 for spent liquor. The contents of lignosulfonic acid and phenolic hydroxyl groups on $C_9$ unit of lignin in the spent liquor were 0.98~0.99, and 1.51~1.66, respectively. These values were remarkably higher than those of C-LS. Especially the content of phenolic hydroxyl group was almost twice that of C-LS. The viscosity of spent liquor after freeze drying was very low compared to C-LS. The dispersing ability of spent liquor was almost equivalent to or more than that of C-LS.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.2
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• pp.181-186
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• 2017

Objective: Leucaena leucocephala (Leucaena) is a perennial tropical legume that can be directly grazed or harvested and offered to ruminants as hay, silage, or fresh. However, Leucaena contain phenolic compounds, which are considered anti-nutritional factors as these may reduce intake, digestibility and thus animal performance. Therefore, the objective of this experiment was to determine effects of Leucaena silage (LS) feeding levels on rumen microbial populations, N-balance and microbial protein synthesis in dairy steers. Methods: Four, rumen fistulated dairy steers with initial weight of $167{\pm}12kg$ were randomly assigned to receive dietary treatments according to a $4{\times}4$ Latin square design. Treatments were as followings: T1 = untreated rice straw (RS; Control), T2 = 70% RS+30% LS, T3 = 40% RS+60% LS, and T4 = 100% LS. Dairy steers were fed rice straw and LS ad libitum and supplemented with concentrate at 0.2% of body weight/d. Results: Results revealed that the rumen microbial population, especially cellulolytic, proteolytic bacteria and fungal zoospores were enhanced in steers that received 60% of LS (p<0.05), whereas the amylolytic bacteria population was not affected by treatments (p>0.05). Protozoal population was linearly decreased with increasing level of LS (p<0.05). Moreover, N-balance and microbial protein synthesis were enhanced by LS feeding (p<0.05) and were the highest in 60% LS group. Conclusion: Based on this study, it could be concluded that replacement of RS with 60% LS significantly improved microbial population and microbial protein synthesis in diary steers.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.616-618
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• 2007

This paper describes the mechanical and electrical test on HVDC submarine cable, Flexible Repair Joint and termination for 180kV. This HVDC submarine cable was manufactured using LS cable's unique skill and would be applied the HVDC submarine cable system in korea. The performance test consist of mechanical test and electrical test. The tensile bending test and tensile test was done as the mechanical test and Electrical test is DC voltage and Impulse test. The tensile bending test carried out 6 times(double of specified times) for maximum reliability. The DC test voltage is $\pm$400kV/1hr. We estimate the lower limit of DC breakdown voltage is 600kV. The impulse test voltage is $\pm$800kV/10shots. The type of developed cables is the MI type. Its insulation consist of paper tapes impregnated with a high viscosity oil. The development of new HVDC cable is available for HVDC underground or submarine power transmission. The developed HVDC cable, FRJ and termination have passed the mechanical and electrical test successfully and showed excellent performance.

• Journal of Life Science
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• v.33 no.11
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• pp.923-935
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• 2023

Rubus crataegifolius (RC), Ulmus macrocarpa (UM), and Gardenia jasminoides (GJ) are well-known folk medicines in Asia used to treat various gastrointestinal disturbances. The present study evaluated the gastroprotective effect of LS-RUG-com, a mixture of commercially prepared powders of RC, UM, and GJ with a ratio of 3:1:2(w/w/w) against HCl/ethanol-induced gastritis, indomethacin-induced ulcers, and esophageal reflux-induced esophageal mucosal damage and Helicobacter pylori infections. In addition, TNF-α and IL-1β expressions were also determined and measured in esophageal tissue. As to HCl/ethanol-induced gastritis, the LS-RUG-com treatment at a dose of 150 mg/kg showed a remarkable anti-gastritis effect. Regarding indomethacin-induced gastric ulcers, the LS-RUG-com treatment had a significant anti-gastric ulcer effect. Furthermore, in the gastroesophageal reflux disease (GERD) model experiment, the LS-RUG-com treatment resulted in the histological recovery of stomach damage and mucosal injuries. Furthermore, the LS-RUG-com treatment led to an increase in gastric content pH, an increase in mucus protection, and a decrease in gastric pepsin output with a significant decrease in TNF-α and IL-1β. As to the Helicobacter pylori infected animal model, LS-RUG-com had a notable inhibitory effect on Helicobacter growth. The use of RC, UM, or GJ in isolation or the LS-RUG-com treatment as whole had good effects in terms of anti-oxidation, anti-neutralization, gastric acid secretion inhibition, and anti-lipid peroxidation, which supported the use of natural products as systemic gastric protective agents. Our results suggest that the LS-RUG-com might be a significant systemic gastroprotective agent that could be utilized for the treatment and/or protection from gastric disturbances and related damage.

• Investigative Magnetic Resonance Imaging
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• v.20 no.4
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• pp.231-240
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• 2016

Purpose: To determine whether liver stiffness (LS) measured by magnetic resonance elastography (MRE) can predict the outcome of radiofrequency ablation (RFA) in hepatocellular carcinoma (HCC) patients. Materials and Methods: A total of 107 patients with Child-Pugh class A liver function who were treated with RFA for single HCC and who had undergone a gradient-echo MRE within 6 months before RFA were included. We evaluated the relationship between the LS values and the ablation volume, local tumor progression (LTP), and intrahepatic distant recurrence (IDR). We also constructed receiver operating characteristic (ROC) curves to examine the role of LS in predicting liver function deterioration, which was defined as an increase of Child-Pugh score by one point or more at 1 year after RFA. Results: There was no significant correlation between LS and ablation volume, and neither time to LTP nor IDR was associated with LS. Among the 66 patients who did not have recurrence 1 year after RFA, 5 patients (7.6%) developed liver function deterioration. A high LS value was significantly associated with development of liver function deterioration after RFA and the area under the ROC curve was 0.764 (95% CI 0.598-0.929, P = 0.003). Conclusion: LS measured by MRE could not predict ablation volume and tumor recurrence. However, high LS values were significantly associated with development of liver function deterioration.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.1
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• pp.49-57
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• 2021

In the production power transmitting of a floating production system like a wind offshore floating, the power cable should be connected from the surface system into the subsea system. The connection between the surface and the subsea system will make the power cable get a dynamic load like current and wave forces. Based on this condition, a dynamic power cable is required to endure external physical force and vibration in the long-term condition. It needs more requirements than static power cable for mechanical fatigue properties to prevent failures during operations in marine environments where the external and internal loads work continuously. As a process to verify, the durability test of dynamic power cables under the marine operation environment condition was carried out by using domestic technology development.

• Korean Journal of Plant Resources
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• v.33 no.6
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• pp.689-695
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• 2020

This study was conducted to improve and supplement the system of cryopreservation for adventitious bulbs induced by tissue cultured bulb-scales of lily (Lilium spp.) cvs. 'Milky way'. The explants, bulblets and bulb-scale-bulblets, were treated to low temperature (4℃) for 7 days prior to the pre-culture. The adventitious bulbs were pre-cultured in Murashige and Skoog (MS) liquid medium supplemented with sucrose (0.3 and 0.7M). The pre-cultured adventitious bulbs were treated to loading solution (LS1 or LS2, C4 or C6) containing 35% of PVS3 (LS1, C4) or 40% of PVS3 (LS2, C6) for 40 min and exposed to dehydration solution (PVS3, B1) containing 50% glycerol and 50% sucrose for 60 min at 25℃. The adventitious bulbs were moved onto droplets containing 3 µl PVS3 on sterilized aluminum foils, and then soaked into liquid nitrogen (LN) for 60 min. The result of highest regrowth rate as 65.7% was obtained in cold treatment (4℃), osmoprotected with LS1 solution, and cultured in PCM3 medium by using bulb-scale-bulblet for cryopreservation. This result shows that droplet-vitrification could be used as a promising method for long-term storage of lily genetic resource.