• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.14 no.2
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• pp.1-10
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• 2018

Structures, systems and components of nuclear power plants should be able to maintain safety even in the event of design-basis accidents such as high-energy line breaks. The high-pressure steam jet ejected from the broken pipe may cause damage to the adjacent structures. The ANSI/ANS 58.2 code has been adopted as a technical standard for evaluating the jet impingement load. Recently, the U.S. NRC pointed out the non-conservativeness of the ANSI/ANS 58.2, because it does not take into account the blast wave effect, dynamic behavior of the jet, and oversimplifies the shape and load characteristics of the supersonic steam jet. Therefore, it is necessary to improve the evaluation method for the high-energy line break accident. In order to evaluate the behavior of supersonic steam jet, an appropriate numerical analysis technique considering compressible flow effect is needed. In this study, numerical analysis methodology for evaluating supersonic jet impingement load was developed and verified. In addition, the conservativeness of the ANSI/ANS 58.2 model was investigated using the numerical analysis methodology. It is estimated that the ANSI jet model does not sufficiently reflect the physical behavior of under-expanded supersonic steam jet and evaluates the jet impingement load lower than CFD analysis result at certain positions.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.5
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• pp.389-399
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• 2024

Currently, shipyards are using ship block supports to hold various pre-erection (PE) blocks during ship construction work. The height adjustment method of the ship block support is performed by workers hammering and driving the wedge part, which requires repetitive high-load work. Accordingly, there are concerns about musculoskeletal diseases and safety accidents. To prevent safety accidents and improve work efficiency, this study developed a block support height adjustment device using a hydraulic cylinder. It was designed considering the ease of movement of the block support height adjustment device and the ease of adjusting the height of the block support by workers within the shipyard. Numerical analysis was conducted to confirm the critical points of the structural members of the designed block support height adjustment device and to verify the safety of the stress-based structure. As a result of the analysis, it was confirmed that the stress occurring at the critical point of the structural member was lower than the design allowable stress, making it structurally safe. Afterwards, the block support height adjustment device was redesigned for lightweight, and after verification of structural safety through numerical analysis, a prototype was manufactured and performance evaluation was conducted.

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.89-103
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• 2006

This study develops the tire/pavement noise measuring trailer that can minimize the effect of various environmental noise and evaluate road noise characteristics without regard to time and spots. As literature reviews, it is examined into road noise characteristics and case studies of various CPX Trailer, and made a development plan of device. Based on these, HEART CPX Trailer is developed and conduct experiments for verification of the semi-anechoic chamber suitability, precision and field application of device. In the result of the experiment for verification of semi-anechoic chamber suitability, we can make sure that it is suitable and reliable among frequency bands. In the test of repetition measurement, we can verify excellent measurement accuracy among speeds and microphone's locations. In case of field tests using HEART CPX Trailer, it is founded that the result is similar to CPB test result carried out by Chung-Ang university in 2003. It can be concluded caused that the effect of environmental noise in and around the road including mechanical noise of a tow car was excluded. This paper confirmed and suggested that HEART CPX Trailer is suitable for evaluation of real road noise characteristics.

• The Journal of Korean Academy of Sensory Integration
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• v.12 no.2
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• pp.25-36
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• 2014

Objective : The purpose of this study is learning the characteristics of literature applying single subject researches in the field of sensory integration therapy of Korean occupational therapy and evaluating the quality level of them. Methods : Analyzed the characteristics of 17 single subject research papers (independent variable, study design, study subject, total number of session, study period, intervention time, intervention place, dependent variable, measuring tool and result) published between 2002 and 2013 using the document delivery service of Korean Society of Occupational Therapy, National Discovery for Science Leaders (NDSL), Nuri Media (DBpia), Research Information Sharing Service (RISS), Korean Studies Information Service System (KISS) and National Assembly Library and evaluated the literatures using quality evaluation scale. Results : According to the analysis result on the literature characteristics, reversal design was the most used study method. Total number of session was 10 sessions to 34 sessions. Study period was 4 weeks to 16 weeks. Intervention time was 8 minutes to 70 minutes and most interventions were done in occupational therapy room or sensory integration therapy room. According to the result of quality level evaluation, 4 papers out of 17 papers were on high level and remaining papers were on intermediate level. However, there was no study which included intervention blind. Conclusion : Suggested standards that need to be supplemented and discussions on qualitative improvement including repetitive research on the mediation effect during the application of the single subject research methodology, the securement of adequate data sections, and processing of a mediation blind. It is expected to be used as basic data for conducting a better qualitative research in the future.

• Journal of Digital Convergence
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• v.11 no.1
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• pp.361-368
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• 2013

The purpose of this study is to know the clinical usefulness of optimal b-values by quantitative, qualitative evaluation of DW-MRI for lesions of benignity and malignity of female pelvis. The b-values used in DWI were 600, 800, 1000, 1200, 1400($s/mm^2$). Mean SNR and CNR of myoma in b-value 800 were the highest result as $84.6{\pm}4.57$(p=0.024) and $50.13{\pm}5.47$(p=0.028), Mean SNR and CNR of cervical cancer were the highest result as $12.0{\pm}2.04$(p=0.047) and $10.6{\pm}1.24$(p=0.001), Mean ADC value in myoma and cervical cancer in b-value 800 were $1.19{\times}10^{-3}mm^2/s$(p=0.008), $0.96{\times}10^{-3}mm^2/s$(p=0.027). As a qualitative analysis, the delineation and conspicuity were the highest result as $4.02{\pm}0.18$(p=0.028), $4.39{\pm}0.25$(p=0.015) on b-value 800. DW-MRI is an important method, and the optimal b values is 800 $s/mm^2$ for differentiation between benign and malignant lesions of female pelvis.

• Journal of Broadcast Engineering
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• v.19 no.5
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• pp.677-686
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• 2014

This paper analyzes the 3D accuracy of stereo images captured from a mobile phone. For 3D accuracy evaluation, we have compared the accuracy result according to the amount of the convergence angle. In order to calculate the 3D model space coordinate of control points, we perform inner orientation, distortion correction and image geometry estimation. And the quantitative 3D accuracy was evaluated by transforming the 3D model space coordinate into the 3D object space coordinate. The result showed that relatively precise 3D information is generated in more than $17^{\circ}$ convergence angle. Consequently, it is necessary to set up stereo model structure consisting adequate convergence angle as an measurement distance and a baseline distance for accurate 3D information generation. It is expected that the result would be used to stereoscopic 3D contents and 3D reconstruction from images captured by a mobile phone camera.

• Journal of Environmental Science International
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• v.28 no.11
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• pp.971-981
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• 2019

This study evaluated the photocatalytic oxidation efficiency of volatile organic compounds by $Cu_2O-TiO_2$ under visible-light irradiation. $Cu_2O-TiO_2$ was synthesized by an ultrasonic-assisted method. The XRD result indicated successful p-n type photocatalysts. However, no diffraction peaks belonging to $TiO_2$ were observed for the $Cu_2O-TiO_2$. The Uv-vis spectra result revealed that the synthesized $Cu_2O-TiO_2$ can be activated under visible-light irradiation. The FE-TEM/EDS result showed the formation of synthesized nanocomposites in the commercial P25 $TiO_2$, the undoped $TiO_2$, and $Cu_2O-TiO_2$ and componential analysis in the undoped $TiO_2$ and $Cu_2O-TiO_2$. The photocatalytic oxidation efficiencies of benzene, toluene, ethylbenzene, and o-xylene with $Cu_2O-TiO_2$ were higher than those of P25 $TiO_2$ and undoped $TiO_2$. These results indicate that the prepared $Cu_2O-TiO_2$ photocatalyst can be applied effectively to control gaseous BTEX.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.5
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• pp.37-49
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• 2023

The drought risk has been increasing recently due to climate change causing the extreme climate to be more frequent. In order to supply agricultural water stably under drought, it is necessary to operate an agricultural reservoir in response to drought. To this end, it is crucial to establish appropriate drought response operation rules considering weather conditions and reservoir status. In the reservoir operation simulation, the supply amount differs from the actual reservoir supply for many reasons, including maintaining water levels for supply and accommodating farmers' requests. So, for a more realistic reservoir operation simulation, it is necessary to reflect the reservoir operation rules of the actual water management site. Therefore, in this study, through a survey, the standards for limitation of agricultural water supply applied to agricultural reservoirs in Korea were investigated, and the criteria for drought response reservoir operation (DRO) were established based on the survey. Then, the DRO was applied to the irrigation period for nine subject reservoirs. The applicability was evaluated by comparing the DRO result to the operation result of HOMWRS (Hydrological Operation Model for Water Resources System). The reservoir drought index, storage rate, and daily supply were compared for evaluation. From the result, DRO showed more stable operation results in most cases against drought as it has fewer days of water supply limitation and a somewhat reservoir storage rate which can be utilized for prolonged drought.

• Korean Journal of Construction Engineering and Management
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• v.16 no.4
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• pp.70-79
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• 2015

With the rise of the interest in a renewable system, the importance of the Life Cycle Cost Analysis(LCCA), an economic evaluation tool, has been increasing. However, there is an inevitable gap between a real cost and an estimation from LCCA because of the uncertainty of the external environment in real world. As the input variables in an analysis, such as a real discount rate and an energy cost, ares subject to change as time goes by, strategic decision on the current operating system is made depending on the real cost. Current economic evaluation approaches have treated only the fluctuation of input variables without consideration of the flexibility in operation, which has consequently led to the impairment on the reliability of LCCA. Therefore, new approach needs to be proposed to consider both the uncertainty of input variables and operational flexibility. To address this issue, the application of the Real Option to LCCA is presented in this study. Through a case analysis of LCCA of a solar heating system, the limits and current status of LCCA are identified. As a result, quantitative presentation of strategic decisions has been added in the new approach to implement the traditional approach.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.63-72
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• 2017

This paper proposes a procedure to improve the operational efficiency of the automotive parts manufacturing process by applying classical IE techniques composed of process analysis, work method analysis, and motion analysis, and a specific application case is outlined. The proposed procedure was developed originally by the Task Force organized in L company's automotive parts manufacturing business unit. The balance efficiency and production capacity were used as measures of operational efficiency. The developed procedure follows the general procedure of analyzing the phenomenon at the manufacturing shop, deriving an improvement solution to solve the problem, evaluating each derived alternative, and implementing it to the field to achieve productivity improvement. Among the methods used in each phase of the procedure, function analysis used in the waste discovery phase and R&R evaluation method used in the alternative assessment phase are unique techniques developed by L company's TF. The R&R Evaluation method techniques are described in detail because this method is highly applicable and extensible. A case of applying developed procedures to improve the EPS motor manufacturing process is discussed. As a result, the line balance efficiency and production capacity were increased to a satisfactory level.