• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.157-162
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• 2003

The sludge oils were produced necessarily in the ships operation, so that it will be the best way to manage the sludge oils inside ship itself from a viewpoint of the prevention of marine oil pollution from ship. The ultrasonic breaking systems which recycle the sludge oil from ship into usable oil to be brunt is recognized as a most possible recycling device. In this regards, the purpose of this study is to examine erosion damage on the SS400 specimen by cavitation and the effect of impact pressure generated from the demolition of the cavity of ultrasonic vibration in the marine sludge oil environment .. The erosion damage of specimen was investigated mainly on weight loss, weight loss rate and maximum erosion rate with variation of the oil temperature as well as the change of space between transducer horn and specimen. The experimental results showed that as the space between ultrasonic vibrator horn and specimen disk increased, the weight loss and weight loss rate decreased and the values were larger in SFO than in SLO. The experimental results can be useful to the development of sludge oil disposing systems and to consider a countermeasure for the prevention of erosion damages by cavitation.

• The Journal of Industrial Distribution & Business
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• v.10 no.6
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• pp.29-37
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• 2019

Purpose - This study intends to analyze Chinese consumers' purchase intention of Korean automobile. The aims of this study investigated to find out how product attributes and brand image affect the consumer's purchase intention of Korean automobiles in China. We consider the product attributes, brand image as evaluation criteria, also recognized as objectives for purchase intention. This study aims to analyze the positive effects on Chinese consumers' purchase intention with the variables by using the research model. Research design, data, and methodology - Based on theory of Purchase Intention, the concept of purchase intention was assessed by two factors: a) product attributes, and b) brand image to test the proposed hypotheses. The survey was conducted for 30 days, from October 17 to November 16 in 2018. With IBM SPSS Statistics 23.0 and IBM SPSS AMOS 23.0, factor analysis and regression, Cronbach's alpha and correlation were tested. 300 samples were used for this analysis. Results - As a main result, product attributes and brand image exerted significant effects on consumer's purchase intention. Thus,

and

were supported. The results showed that the product attributes, brand image had positive effects on purchase intention. The findings of this thesis are as follows: Firstly, automobiles' quality factors were divided into two categories like product properties (price, performance, design, economy, and safety), and brand image (awareness, favorability, reliability, and familiarity). Second, it showed that product properties and brand image had positive impacts on purchase intention of consumer. Conclusions - The impact of product attributes and brand image on consumer perceived value of Korean automobiles in China can be seen as a universal psychology of consumers who trust automobile products such as high quality, technology, ets. The results offer some insights into the extended model and have important managerial implications for Korean automobile enterprise. As the findings of this thesis show, all strategic orientations have significant and positive effects on the ability of innovation. At the same time, automobile company must pay attention to quality. As the relationship between the automobiles' performance and brand image were positive and significant, automobile companies should have comprehensive strategic orientations focused on strengthening these factors.

• Journal of Korean Neurosurgical Society
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• v.57 no.5
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• pp.342-349
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• 2015

Background : Higher reperfusion rates have been established with endovascular treatment for acute ischemic stroke patients. There are limited data on the comparative performance of mechanical thrombectomy devices. This study aimed to analyse the efficacy and safety of the stent retriever device (Solitaire stent) by comparing procedure time, angiographic outcome, complication rate and long term clinical outcome with previous chemical thrombolysis and mechanical thrombectomy using penumbra system. Method : A retrospective single-center analysis was undertaken of all consecutive patients who underwent chemical thrombolysis and mechanical thrombectomy using Penumbra or Solitaire stent retriever from March 2009 to March 2014. Baseline characteristics, rate of successful recanalization (modified Thrombolysis in Cerebral Infarction score 2b-3), symptomatic intracerebral hemorrhage, procedure time, mortality and independent functional outcomes ($mRS{\leq}2$) at 3 month were compared across the three method. Results : Our cohort included 164 patients, mechanical thrombectomy using stent retriever device had a significant impact on recanalization rate and functional independence at 3 months. In unadjusted analysis mechanical thrombectomy using Solitaire stent retriever showed higher recanalization rate than Penumbra system and chemical thrombolysis (75% vs. 64.2% vs. 49.4%, p=0.03) and higher rate of functional independence at 3 month (53.1% vs. 37.7% vs. 35.4%, p=0.213). In view of the interrelationships between all predictors of variables associated with a good clinical outcome, when the chemical thrombolysis was used as a reference, in multiple logistic regression analysis, the use of Solitaire stent retriever showed higher odds of independent functional outcome [odds ratio (OR) 2.62, 95% confidence interval (CI) 0.96-7.17; p=0.061] in comparison with penumbra system (OR 1.57, 95% CI 0.63-3.90; p=0.331). Conclusion : Our initial data suggest that mechanical thrombectomy using stent retriever is superior to the mechanical thrombectomy using penumbra system and conventional chemical thrombolysis in achieving higher rates of reperfusion and better outcomes. Randomized clinical trials are needed to establish the actual benefit to specific patient populations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.483-490
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• 2016

Automobile door latch is a fine design and assembly techniques are required in order to produce them in a small component assembly shape such as a spring, injection products, a small-sized motor. The door latch is fixed to not open the door of the car plays an important role it has a direct impact on the driver's safety. In this study, during trimming of the terminals of the connector main components of the car door latch, reduce rollover and conducted a research to find a suitable effective shear surface. Using the Taguchi method with orthogonal array of Finite Element Analysis and optimal Design of Experiments were set up parameters for the shear surface quality of the car door latch connector terminals. The design parameters used in the analysis is the clearance, the radius, and the blank holding force, the material of the connector terminal is a C2600. Trimming process optimum conditions suggested by the analysis has been verified by experiments, the shear surface shape and dimensions of a final product in good agreement with forming analysis results.Taguchi method from the above results in the optimization for the final rollover and effective shear surface improved for a vehicle door latch to the connector terminal can be seen that the applicable and useful for a variety of metal forming processes other than the trimming process is determined to be applicable.

• Journal of Korean Society on Water Environment
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• v.33 no.2
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• pp.170-180
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• 2017

The study used jet water flow, ultra-sonication and ozonation system units to investigate impact of the unit components on water quality of stagnant Yeo-cheon River reach, Korea. Samples were collected at six locations, before operation and after 1, 3 and 6 hrs of operation. By operating the water flow unit only, dissolved oxygen increased as high as 90% after 3 hr at 25 m downstream of the device and Chl-a was reduced by 80%. Incorporating sonication, greater than 80% of Chl-a was removed even at 100 m distance from the device. Besides, total dissolved phosphorus was reduced from an average value of $420({\pm}70){\mu}g/L$ before ultrasonic irradiation to $160({\pm}40){\mu}g/L$ after the treatment. Releasing ozone into the flow with sonication, Chl-a was considerably removed from the water column and ammonia nitrogen was also decreased to average value of $20{\mu}g/L$ from $60{\mu}g/L$. However, as only $3{\ast}10^{-3}mg/L$ of ozone was used for safety purpose and due to brief reaction time it takes, effect of integrating ozone to the system covered limited area. Generally, combining sonication to jet flow is promising in preventing algal bloom formation since it has effectively removed Chl-a from the water column.

• Korean Journal of Environment and Ecology
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• v.34 no.4
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• pp.282-293
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• 2020

This study investigated a long-term variation trend of water quality, fish compositions, and ecological health conditions in the Gwanpyeong stream located in the nearby Daejeon metropolitan city to understand the impact of urban development projects on the aquatic ecosystem. The sampling was made in four surveys (2009, 2010, 2016, 2019) before and after urbanization. The urban development was conducted in 2008, resulting in the stream's ecological disturbance, and the stream restoration was conducted in 2012. Thus, stream monitoring was conducted to analyze the ecological trends before and after the restoration. The multi-metric models for Fish Assessment Index(FAI) and necropsy-based Health Assessment Index(HAI) were applied in the fish community and organ-level, respectively, to assess the ecological health of the stream. Minimum turbidity and chlorophyll-a(Chl-a) occurred in the mid-stream(St. 2), and this was probably due to rapid current velocity in the riffle zone. We collected 18 fish species, and the dominant species was Zacco platypus (40.6%). In 2016 immediately after the stream restoration, the relative proportions of sensitive species and insectivore species were the highest along with highest values in the species diversity and species richness index, resulting in the best condition in the ecological health, based on FAI model values. However, the ecological health, based on the FAI, became worse in the latest survey conducted in 2019. The analysis of the HAI model based on the organ-level approach showed skin erosion in the fish of upper stream, kidney defects in downstream, and the liver and gill defects observed in all sites, indicating that the anatomical health was also affected.

• Journal of the Korean GEO-environmental Society
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• v.21 no.10
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• pp.11-16
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• 2020

Korea's agricultural reservoir is one of the country's major infrastructures and plays an important role in people's lives. However, aging reservoirs are a risk for life and property. Currently, large and small dams and reservoirs have been constructed nationwide for more than 40 years of aging. Dams and reservoirs built nationwide are managed by various institutions. Therefore, it is difficult to manage all dams and reservoirs due to cost and time. Managers in the field with less management personnel and lack of expertise should be able to quickly identify risk factors for multiple reservoirs. In this study, risk factors such as seepage, leakage, settlement slide, crack and erosion were selected. To assess the risk of the items, we used the analytical hierarchical process (AHP), one of the Multi-Criteria Decision Making (MCDM) methods. The analysis showed that seepage has the greatest impact on reservoir collapse. It is judged that the priority of detailed diagnosis can be determined by evaluating the risk of dam reservoir collapse in a convenient way in advance using the calculated weight.

• Korean Journal of Construction Engineering and Management
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• v.16 no.1
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• pp.64-73
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• 2015

The theft of construction equipments and materials at construction sites is one of the risk factors that may affect to the productivity as well as the progress of the project. However, managers of the construction site have paid little attention to the security measure, therefore the theft loss at construction sites has been occurred repeatedly every year. In this study the situation analysis has been carried out for the present condition of theft loss of construction equipments and materials as well as its prevention measure based on the questionnaire survey targeting field managers, experienced theft loss at the site, as a part of base study to set up a security measure of construction sites. The main content of this study is analyzing characteristics of theft loss and the degree of impact and risk by it at construction sites, then reviewing the direction of the prevention plan establishment for the future through the analysis of the importance and utilization level of prevention measures. The result of this study would give an opportunity to create an awareness against the theft loss at construction sites as well as can be utilized as a basic survey for the systematic development of concerned prevention measures.

• Journal of Korean Society of Forest Science
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• v.107 no.1
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• pp.59-70
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• 2018

The objective of this study was to develop erosion control dam for preventing disaster in consideration of characteristics of forested catchment near urban area, and to assess its stability and functionality to see its practicability in the field. Two types of hybrid erosion control dams were developed including debris flow prevention dam by using pillar and float board screen type and debris flow control dam by using groyne. Also, review about their static (sliding, overturning, bearing capacity) and dynamic (member force) stability was carried out. According to the result, most of the assessed items met standard safety level although there were some cases where assessed items were short of stability criteria against impact. Also, after miniature flume experiments based on the developed erosion control dam to prove structure function (material catch, deposit), it turned out the dam decreased flow sediment amount and velocity while increasing sediment-capturing capacity by 3.5 times on average compared to the one controlled without erosion control dam. When function of erosion control dam for forested catchment near urban area is quantified based on future flume experiments in a variety of conditions, the dams can be practically used in the urban area, contribution to effectively reducing debris flow damage.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.2
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• pp.191-198
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• 2008

Flow accelerated corrosion (FAC) phenomenon of low alloy carbon steels in nuclear power plant has been known as one of major degradation mechanisms. It has a potential to cause nuclear pipe rupture accident which may directly impact on the plant reliability and safety. Recently, the equipotential switching direct current potential drop (ES-DCPD) method has been developed, by the present authors, as a method to monitor wall loss in a piping. This method can rapidly monitor the thinning of piping, utilizing either the wide range monitoring (WiRM) or the narrow range monitoring (NaRM) technique. WiRM is a method to monitor wide range of straight piping, whereas NaRM focuses significantly on a narrow range such as an elbow. WiRM and NaRM can improve the reliability of the current FAC screening method that is based on computer modeling on fluid flow conditions. In this paper, the measurements by ES-DCPD are performed with signal sensitivity analyses in the laboratory environment for extended period and showed the viability of ES-DCPD for real plant applications.