• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.7
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• pp.3341-3352
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• 2011

In this study, characteristics of wastewater treatment of sewage intermittently mixed with industrial wastewater is examined by investigating the operational status of each unit operation and measuring water quality. The bioreactor operating condition was measured for MLSS concentration 2,000~3,000 mg/L, HRT 5.3~16.3 hour, SRT 2.8~66.6 day, and SVI frequently showed the value above 200 which was higher than the optimal range of 50~150. It is thought that the sludge is not in suitable condition for sedimentation caused by the incoming industrial wastewater. When industrial wastewater is come into the system, MLDO inside of bioreactor rapidly increased, rate of nitrification is steeply decreased, and Pin floc. is spilled in the secondary clarifier. In the observance of microorganism showed that various bacterial floc. and ciliata were found as well as actinomycetes and filamentous bacteria(Sphaeotilus) which is known to cause bulking. Efficiency of each unit operation was fairly good in average. However, efficiency of the bioreactor treatment showed high fluctuation by unstable operating condition by intermittently incoming industrial wastewater.

• Korean Security Journal
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• no.42
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• pp.179-203
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• 2015

Nowadays college students in South Korea experience much stress related to job search due to the continuing unemployment crisis. Particularly, students who hold a degree in Security Services suffer from such stress at a higher level compared to other students because of the specific qualifications sought by potential employers. Therefore, this study investigates the effect of the stress related to job search on career maturity among the students of Security Services. The authors surveyed 250 students of Security Services from 7 colleges in Gyeonggi, Jeolla, and Gyeongsang provinces. Before distributing the questionnaire, its validity and reliability were assessed through the consultations with experts in the related fields. The data collected was examined via various statistical methods, including factor, reliability, correlation, and regression analyses using SPSS 20.0. The results indicated that socio-demographic characteristics affected job search stress and career maturity. Additionally, it was found that the job search-related stress of the students influenced their career maturity. To illustrate, job search stress and career maturity were positively related. Based on the results of the analyses, the authors confirm that the students of Security Services are suffering from a high level of stress resulting from job search, which impacts their career selection. Finally, policy implications are discussed, including alleviating the stress by providing diversified career choices to the students.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.3
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• pp.249-255
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• 1995

This study was conducted to investigate the effects of some soil conditioners, such as polyacrylamide(PAM), polyvinylalcohol(PVA) and Bitumen emulsion, on aggregate formation and stability, wetting angle, sorptivity and penetrability of the soil with different textures : sand, sandy loam, loam and clay loam. A pot experiment was carried out to find out the effect of treatment on the germination and growth of lettuce with three textures : sand, sandy loam and silt loam. Soil aggregates larger than 2mm in untreated soils at dry condition were naught in sand, 45% in sandy loam, 80% in loam and 90% in clay loam. Treatments of soil conditioners tended to increase the occurrence of soil aggregate larger than 2mm, which were 20~25% in sand, 55~75% sandy loam, but not affected greatly aggragate occurence in loam and clay loam. The aggregate instability was decreased by the soil conditioner treatment. The wetting angles of the soils were greatly changed by hydrophobic of Bitumen, but those were changed slightly by PVA and PAM application. The sorptivity and penetrability data indicated that the effects of different materials on these parameters differed depending upon soil texture. Application of PVA and PAM were no effect exceptive in sand. Application of Bitumen revealed that water movement was not showed in all soils. The germination rate, root weight and top plant weight of lettuce were increased in all soils by PAM treatment as compared to untreated soils. Particularly the greater effect was occurred in sand soil than in sandy loam and silt loam. PAM increased greatly the moisture content and air phase of soils.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.21 no.3
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• pp.103-111
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• 2016

Seasonal dynamics of kelp forest-forming algae, Ecklonia cava population formed following the large-scale disturbance by Typhoon 'Bolaven' in August 2012 were investigated in Jeju Island, Korea. Morphological characteristics, recruits density, mortality rate, total density and biomass were monitored bimonthly from June 2013 to June 2015. Total and longest blade lengths, and individual weight of E. cava showed distinct seasonal trends. Stipe length increased from winter to spring, but did not show increase or reduced from summer to autumn. This indicates that morphological characteristics of E. cava are mainly affected by the change of blades. The optimal temperature for E. cava growth was about $15-18^{\circ}C$ during winter to spring while the growths were inhibited at the water temperature above $20^{\circ}C$ during summer. E. cava exhibited very low recruitment during spring-summer. However, high recruitment was observed on April 2015 when canopy cover was very low due to low density. This indicates that recruitment of E. cava was controlled not by seasonal effects but by physical factors such as canopy and space. The mortality rate of juvenile plants was highest due to their unstable settlement. By June 2015, 34 months after the disturbances, E. cava was almost recovered to the pre-disturbance population size structure. These results suggest that recovery of kelp forest following the large-scale disturbance requires a considerable period of time (more than three years). This study should provide valuable ecological information on management, restoration and protection of kelp species.

• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.254-261
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• 2014

The transformer is a static electrical device that transfers energy by inductive coupling. Then, heat is occurred at coils, inner transformer was filled with insulating oils for cooling and insulation. Although mineral oil as insulating oil has been widely used, it does not meet health and current environmental laws because it is not biodegradable. Therefore, in this study, the diglycerol ester was synthesized with diglycerol and fatty acids (oleic acid and caprylic acid) over various catalysts for insulating oil having biodegradability, high flash points and low pour points. The sulfated zirconia ($SO_4{^{2-}}/ZrO_2$) catalyst prepared at different calcination temperature shows the highest conversion of fatty acids at $600^{\circ}C$ due to crystallinity and high density of acid sites per surface area. When the molar ratio of oleic acid and caprylic acid is 1:3, the diglycerol ester shows superior insulation properties that are the flash point of $306^{\circ}C$ and pour point of $-50^{\circ}C$. The insulation properties of synthesized diglycerol ester shows the pour point of $-50^{\circ}C$ and the flash point of over $300^{\circ}C$. Therefore, diglycerol ester is superior to the vegetable oils in insulation properties.

• Journal of Family Resource Management and Policy Review
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• v.25 no.2
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• pp.13-24
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• 2021

The purpose of this study was to prepare basic data to set the support direction for low-income households in a socioeconomic crisis situation. The study examined the effect of socioeconomic deprivation experience on the longitudinal changes in family conflict and family relationship satisfaction of low-income households. Using five-year data from the 10th to 14th sessions of the Korean Welfare Panel, we examined the longitudinal changes in family conflict and family relationship satisfaction, and the effect of socioeconomic deprivation experience from the reponses of 803 low-income households. We found that the family conflict of low-income households decreased to a weak level with the change of time, and the rate of change in family relationship satisfaction was not meaningful. In the case of families who experienced early socioeconomic deprivation, their initial value of family conflict was higher than that of inexperienced households, and the rate of change was not significant. The results of this study show that when low-income households experience socioeconomic deprivation, they feel psychological pressure and an increase in family anxiety, resulting in high family conflict and low family relationship satisfaction. On the basis of the study results, we recommend extending economic and social assistance to low-income households in the current socioeconomic crisis. The state is also encouraged to help families manage conflicts on their own and resolve problems.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.478-485
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• 2018

Aids to Navigation (AtoN) is one of the marine traffic safety facilities that promotes the safety of maritime traffic and enhance ship's operational efficiency. However, functional failure of AtoN due to ship's collision or bad weather conditions leads to inconvenience or navigational risk to various users such as the ship operators. For insstance, the largest container port in Korea, Busan Port has experienced a total of 400 AtoN accidents in the past 12 years (2006-2017).Therefore, an average of 20.6 days of recovery time is required, which increases the maritime safety anxiety for AtoN users. is the objective of this study was to present the quantitative support of the users for the prevention of AtoN accidents and the improvement of the feasibility of implementing more efficient management in Korea. A survey was conducted on the users of Busan port areas to investigate general perception of AtoN in general and the accidents that have happened, and to estimate the economic value of navigational risk reduction by implementing effective AtoN management measure. Using the representative non-market valuation method for environmental or public goods known as contingent valuation method (CVM), the economic value granted to users for the AtoN services in Busan port was estimated to at least 16 billion won. Therefore, these finding could be used by AtoN managers and/or policy makers as a valuable data to identify the users' need of various AtoN services including Busan Port and to establish and implement more efficient management plan.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.453-459
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• 2019

In this study, the influence factors on the stability of the O/W (oil in water) emulsions prepared with coconut oil and the nonionic mixed surfactant (Tween 80-Span 80) were evaluated. The concentration and HLB value of the nonionic mixed surfactant, and the degree of agitation were used as manufacture factors. The stability of prepared O/W emulsions were measured with the mean droplet size, zeta-potential, emulsion stability index (ESI), and thermal instability index (TII). The mean droplet size of the prepared O/W emulsions was from 100 to 200 nm. As the concentration of mixed surfactant and the homogenization speed increased, the droplet sizes decreased, while the zeta-potential values increased. The effect of HLB values increased in the order of 6.0, 10.0 and 8.0, and at the HLB value of 8 the smallest mean droplet size as 120 nm was obtained whereas the largest value of the zeta-potential between 10 and 60 mV. From the results of ESI and TII, the stability of prepared O/W emulsions increased in order of 6.0, 10.0 and 8.0 of HLB values, and ESI and TII values were above 80% and below 20% respectively at HLB value of 8.0.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.75-84
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• 2019

The purpose of this study was to investigate whether there is a difference between the deokhu activities and the flow level of the deokhu group. We also tested whether there are any real differences in emotion before and after the deokhu activities. The study included 227 adults and results were as follows. First, the deokhu group had a high cost of investing and a high rate of one-day investments, particularly for one-week activities and years of duration compare to the non-deokhu group. Second, the higher the degree to which they perceived themselves as deokhu and the level of deokhu activities were higher in flow. and the group of deokhu was more absorbed than the non-deokhu group. Third, there has been no change in positive and negative feelings before and after deokhu activities in the non-deokhu group. For the deokhu group, the positive emotions of happiness, joy, tranquility, pleasure increased and negative emotions such as anger, anxiety, sadness, shame, and guilt were significantly reduced after deokhu activities. The perception of deokhu and deokhu activities have positive functions that increase the level of flow, relieve negative feelings and enhance positive emotions.

• Korean Journal of Remote Sensing
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• v.34 no.6_3
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• pp.1415-1425
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• 2018

Kompsat-5 is the first Earth Observation Satellite which is equipped with an SAR in Korea. SAR images are generated by receiving signals reflected from an object by microwaves emitted from a SAR antenna. Because the wavelengths of microwaves are longer than the size of particles in the atmosphere, it can penetrate clouds and fog, and high-resolution images can be obtained without distinction between day and night. However, there is no color information in SAR images. To overcome these limitations of SAR images, colorization of SAR images using Cycle GAN, a deep learning model developed for domain translation, was conducted. Training of Cycle GAN is unstable due to the unsupervised learning based on unpaired dataset. Therefore, we proposed MS Cycle GAN applying multi-scale discriminator to solve the training instability of Cycle GAN and to improve the performance of colorization in this paper. To compare colorization performance of MS Cycle GAN and Cycle GAN, generated images by both models were compared qualitatively and quantitatively. Training Cycle GAN with multi-scale discriminator shows the losses of generators and discriminators are significantly reduced compared to the conventional Cycle GAN, and we identified that generated images by MS Cycle GAN are well-matched with the characteristics of regions such as leaves, rivers, and land.