• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.749-756
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• 2000

Chemical application, one of the most important crop management processes happened to cause spray drift, that would threaten farmers in field as well as dwellers in rural region. Spray drift was affected by micro-meteorological parameters. In Korea, a boom sprayer was introduced but good effects of a boom sprayer was not evaluated. A study to evaluate short distance drift characteristics of a boom sprayer in paddy fields has been undergoing and determining wind characteristics in paddy field was the main purpose of this paper. Micro-meteorological information has been pre-requisite information for evaluating drift in both long and short distances or in both theoretical and experimental ways. Wind velocity, Reynolds stresses, turbulence intensity, skewness, kurtosis etc. were evaluated with height from the ground using a 2-dimensional probe and a hot wire anemometer system.

• Earthquakes and Structures
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• v.25 no.1
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• pp.69-78
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• 2023

Life-cycle performance analysis of a reinforced concrete box section bridge was generated. Moreover, Monte Carlo simulation with important sampling (IS) was used to simulate the bridge material and load uncertainties. The bridge deterioration model was generated with the basic probabilistic principles and updated according to the measurement data. A genetic algorithm (GA) with the response surface model (RSM) was used to determine the deterioration rate. The importance of health monitoring systems to sustain the bridge to give services economically and reliably and the advantages of fiber-optic sensors for SHM applications were discussed in detail. This study showed that the most effective loss of strength in reinforced concrete box section bridges is corrosion of the reinforcements. Due to reinforcement corrosion, the use of the bridge, which was examined, could not meet the desired strength performance in 25 years, and the need for reinforcement. In addition, it has been determined that long-term health monitoring systems are an essential approach for bridges to provide safe and economical service. Moreover the use of fiber optic sensors has many advantages because of the ability of the sensors to be resistant to environmental conditions and to make sensitive measurements.

• The Journal of the Korea Contents Association
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• v.15 no.6
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• pp.379-391
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• 2015

This study aims to understand family support and self-efficacy-mediated structural relation of college students' unemployment stress with their adaptation to school life. Findings of the research are summarized as follows. The study looked into how unemployment stress would directly affect self-efficacy, family support and adaptation to school life. It was found that the unemployment stress would have immediate negative effects on the self-efficacy, family support and adaptation to school life. In addition, the study noticed that with both family support and self-efficacy applied as mediating factors, unemployment stress influences college students' adaptation to school life indirectly and negatively. After the investigation on the immediate effects of family support in relation to the self-efficacy, the study indicated that family support has an immediate positive influence on the self-efficacy. In terms of self-efficacy, it appeared to affect adaptation to school life both positively and directly but, its indirect effects on the adaptation to school life was not confirmed. The study failed to find any direct influence of the family support on adaptation to school life but learned that the family support causes an indirect positive effect through self-efficacy, the mediating factor. In conclusion, the study suggests that adaptation to school life improves as long as unemployment stress decreases, while the family support and the self-efficacy are enhanced.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4D
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• pp.345-356
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• 2012

Road pavement requires repetitive maintenance works to maintain satisfactory service level to the public. However, the repetitive maintenance works upon deteriorated pavement structure make negative effects to deterioration speed. It often leads to inefficient use of limited budget. For that reason, the pavements require reconstruction work to recover their original performance. Recently, construction demands in the Korean national highway have already been reached to maximum level, and the aged pavements start to demand much more reconstruction works. However, in the real world, road agencies have often been confused when they determine maintenance design for such aged road sections due to budget constraint. It is because there is no reliable long-term maintenance strategy that supports their decision making. To support their decision making, this paper aimed to suggest the best maintenance strategy considering changing process of pavement performance by repetitive maintenance works. As an analysis method, probability distribution and hazard function to estimate the life expectancy were adopted, and then the results were used for long-term life cycle cost analysis with deterministic or Monte-Carlo method under various scenarios. As an empirical study, the Korean national highway data that has long-maintenance history data since 1986 has been applied. Last, this paper considered quality assurance of maintenance work to improve maintenance quality. These could be important information as a part of long-term maintenance strategy of pavement.

• Ocean and Polar Research
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• v.40 no.3
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• pp.161-167
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• 2018

We examined the effect of salinity and water temperature on hatching and survival rates of fertilized eggs of hybrid grouper (Epinephelus fuscoguttatus ♀ ${\times}$ E. lanceolatus ♂) at different developmental stages, determining optimal conditions for their long-distance transportation. Deformities and hatching rates of fertilized grouper eggs were observed at salinities of 24, 27, 30, 33, 36, and 39 psu. The optimal salinity was determined to be 36 psu, with a survival rate of $70.0{\pm}2.0%$. Transportation experiments at 36 psu were conducted at water temperatures of 21, 24, 27, and $30^{\circ}C$, different developmental stages such as morula, 5-myomere, and tail beating for hatching and survival rates. The optimal water temperature and developmental stage for transporatation were $30^{\circ}C$ and tail beating stage and those hatching rates were $50.6{\pm}1.9%$ and $86.3{\pm}1.3%$, respectively. At $21^{\circ}C$, the survival rate by transportation water temperature was highest ($73.1{\pm}10.6%$), but the hatching rate ($17.1{\pm}3.1%$) was lowest. Therefore, the hybrid grouper fertilized eggs (E. fuscoguttatus ♀ ${\times}$ E. lanceolatus ♂) can be most efficiently produced under long-distance transportation conditions during the tail beating stage and at a water temperature of $30^{\circ}C$.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.5
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• pp.482-490
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• 1997

The effects of strain amplitude. test temperature and stress on the fatigue properties for Ti-Ni wires were investigated using a rotary bending fatigue tester specially designed for wires. The fatigue test results were discussed in connection with the static tensile properties. The DSC measurement was conducted after fatigue test in order to clarify the change of transformation behavior due to the progress of fatigue. Under the temperature below or near the Af, the strain amplitude($\varepsilon_a$)-failure life (Nf) curve showed to be composed of three straight lines with two turning points. Of the 2 turning points, the upper one was coincident with the elastic limit strain and the lower one with the proportional limit strain. With rising of the test temperature above Af, the pattern of $\varepsilon_a$-Nf curve changed gradually to composition of 2 straight lines. The $\varepsilon_a$-Nf curve shifted depending on test temperature. In the short and medium life zones, the higher the temperature was, the shorter the fatigue life. However, in the long life zone, above the Af temperature, the fatigue life was not affected by the temperature. The transformation enthalpy measured after fatigue test was dependent on Nf, $\varepsilon_a$, and test temperature.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.24
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• pp.10971-10975
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• 2015

Objective: To investigate bladder and intestinal function recovery and quality of sexual life after laparoscopic nerve-sparing radical hysterectomy (LNRH) for treatment of early invasive cervical carcinoma. Methods: Subjects included patients who underwent radical hysterectomy by laparotomy who were randomly assigned to 2 groups: 30 patients who underwent LNRH and 35 classical laparoscopic radical hysterectomy (LRH). We assessed the patients general clinical information, surgical characteristics, pathological findings, and adjuvant therapies. A urodynamic study was used to assess bladder function. Intestinal function recovery and quality of sexual life were evaluated by questionnaire. Results: No significant differences were found in age, surgery characteristics, pathological findings, adjuvant therapies, and main adverse effects between the 2 groups. The mean duration of the postoperative catheterization (DPC) in group LNRH was shorter than that in group LRH (P < 0.001). The maximum flow rate, maximum cystometric capacity, maximum detrusor pressure and urinary complications in group LNRH were better than those in group LRH. The quality of sexual life evaluated according to the female sexual function index (FSFI) was better in group LNRH than in those who underwent LRH. The intestinal function of patients in group LNRH also recovered better compared with patients in group LRH.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.8
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• pp.556-562
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• 2008

The building HVAC systems have very different qualities of performance and durability with the superintendent's ability for management and maintenance. The poor management of these systems finally lead to the shortening of the life expectancy and result in the increase of operating costs and energy consumptions due to low efficiencies. This study presents an example of appropriate use of the LCC(Life Cycle Cost) analysis in a process of maintaining and repairing old HVAC equipments, by demonstrating the difference of optimal economic life, decrease of running cost, and energy consumption according to the management level of the HVAC equipments. But there are no reliable life expectancy and performance history data at present for optimal management of various building service equipments. Therefore, it is necessary to construct long-term database on operation results of them for more accurate and optimized LCC analysis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.2
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• pp.127-133
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• 2019

Seahorses have long been used as ornamental and medicinal products. The sea horse Hippocampus abdominalis has a beautiful color and unique shape and is also used for ornamental purposes and as a traditional medicine in China. This study examined the value of H. abdominalis as a health functional food or food additive. H. abdominalis was hydrolyzed using seven proteases: flavourzyme, neutrase, alcalase, trypsin, kojizyme, pepsin and protamex. The yields of all of the enzyme hydrolysates were higher than that of the aqueous extract. Of the enzymatic hydrolysates, seahorse Protamex hydrolysate (SHP) gave the highest yield and had excellent antioxidant and angiotensin-I converting enzyme inhibitory activities. It protected Vero cells against oxidative by 2,2-azobis-(2-amidinopropane) dihydrochloride (AAPH) and antihypertension in Spontaneously Hypertensive Rats. This study attempted to demonstrate H. abdominalis as a health functional food or food additive in the future.

• Journal of Microbiology and Biotechnology
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• v.29 no.4
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• pp.518-526
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• 2019

Pueraria montana var. lobata is a bioactive substance with various beneficial health effects and has long been extensively used as a traditional medication for the treatment of fever, acute dysentery, diabetes, and cardiovascular diseases in Northeast Asian countries. The purpose of this study was to evaluate the cytoprotective activity of Pueraria montana var. lobata ethanol extract (PLE) for ultraviolet B (UVB)-induced oxidative stress in human dermal fibroblasts (HDF). It was hypothesized that PLE treatment ($25-100{\mu}g/ml$) would reduce intracellular reactive oxygen species (ROS) levels as well as increase collagen production in UVB-irradiated HDF. The results confirmed this theory, with collagen production increasing in the PLE treatment group in a dose-dependent manner. In addition, regulators of cellular ROS accumulation, including HO-1 and NOQ-1, were activated by Nrf2, which was mediated by PLE. Hence, intracellular levels of ROS were also reduced in the PLE treatment group in a dose-dependent manner. In conclusion, PLE increases collagen production and maintains hyaluronic acid (HA) levels in human dermal fibroblasts exposed to UVB-irradiation, thereby inhibiting photoaging.