• Journal of Energy Engineering
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• v.24 no.1
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• pp.149-163
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• 2015

In this study, we conducted study on the confirmation of thermal-hydraulic safety for Mast assembly with Computational Fluid Dynamics(CFD) analysis. Before performing the natural convection analysis for the Mast assembly by using CFD code, we validated the CFD code against two benchmark natural convection data for the evaluation of turbulence models and confirmation of its applicability to the natural convection flow. From the first benchmark test which was performed by Betts et al. in the simple rectangular channel, we selected standard k-omega turbulence model for natural convection. And then, calculation performance of CFD code was also investigated in the sub-channel of rod bundle by comparing with PNL(Pacific Northwest Laboratory) experimental data and prediction results by MATRA and Fluent 12.0 which were performed by Kwon et al.. Finally, we performed main natural convection analysis for fuel assembly inside the Mast assembly by using validated turbulence model. From the calculation, we observed stable natural circulation flow between the mast assembly and pool side and evaluated the thermal-hydraulic safety by calculating the departure from nucleate boiling ratio.

• Journal of Sensor Science and Technology
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• v.10 no.1
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• pp.1-8
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• 2001

Conventional microgyroscopes of vibrating type require resonant frequency tuning of the driving and sensing modes to achieve high sensitivity. These tuning conditions depend on each fabricated microgyroscopes, even though the microgyroscopes are identically designed. A new micromachined resonator, which is applicable to microgyroscopes with self-toning characteristics, is presented. Since the laterally driven two degrees of freedom (2DOF) resonator was designed as a symmetric structure with identical stiffness in two orthogonal axes, the resonator is applicable to vibrating microgyroscopes, which do not need mode tuning. A dynamic model of the resonator was derived considering gyroscopic application. The dynamic model was evaluated by experimental comparison with fabricated resonators. The microgyroscopes were fabricated using a simple 2-mask-process of a single polysilicon layer deposited on an insulator layer. The feasibility of the resonator as a vibrating microgyroscopes with self-tuning capability is discussed. The fabricated resonators of a particular design have process-induced non-uniformities that cause different resonant frequencies. For several resonators, the standard deviations of the driving and sensing frequencies were as high as 1232Hz and 1214Hz, whereas the experimental average detuning frequency was 91.75Hz. The minimum detuned frequency was 68Hz with $0.034mVsec/^{\circ}$ sensitivity. The sensitivity of the microgyroscopes was low due to process-induced non-uniformity; the angular rate bandwidth, however, was wide. This resonator could be successfully applicable to a vibrating microgyroscopes with high sensitivity, if improvements in uniformity of the fabrication process are achieved. Further developments in improved integrated circuits are expected to lower the noise level even more.

• Clinics in Shoulder and Elbow
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• v.12 no.2
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• pp.167-172
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• 2009

Purpose: We wanted to evaluate the results of treating acromioclavicular joint dislocation using an AO hook plate. Materials and Methods: Between February 2008 and September 2009, 10 patients underwent implant removal after surgical treatment of acromioclavicular joint dislocation using a AO hook plate. The Constant-Murley scoring system was administered postoperatively for evaluating the clinical results, and simple X-ray was taken for evaluating the state of reduction. Results: All cases showed satisfactory results on the clinical and radiological study. The mean Constant-Murley score at follow-up was 90.5 (range: 84~95). Three patients had some degree of discomfort with the hook plate, but these symptoms were relieved on removal of the plate. The radiological evaluation showed restoration of the vertical displacement of the clavicle in all the patients. No complications occurred such as infection, plate failure or redislocation after removal of the plate. Conclusion: The short term follow-up results of treating acromioclvicular joint dislocation using an AO hook plate were satisfactory both clinically and radiologically.

• Clinics in Shoulder and Elbow
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• v.20 no.3
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• pp.117-125
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• 2017

Background: To compare the clinical outcomes of arthroscopic capsular release in patients with and without inferior capsular release for shoulder stiffness. Methods: Between January 2010 and December 2015, 39 patients who underwent arthroscopic capsular release for shoulder stiffness were enrolled and randomized into two groups. In group I, 19 patients underwent arthroscopic capsular release of the rotator interval and anterior capsule. In group II, 20 patients underwent arthroscopic capsular release of the anterior to inferior capsule, including the rotator interval. The American Shoulder and Elbow Surgeons score, Constant scoring system, Simple Shoulder Test, visual analogue scale for pain, and range of motion (ROM) were used for evaluation before surgery, at 3, 6, and 12 months after surgery and on the last follow-up. Results: Preoperative demographic data revealed no significant differences (p>0.05). The average follow-up was 16.07 months. Both groups showed significantly increased ROM at the last follow-up compared with preoperative (p<0.05). At the last follow-up, no statistical differences were found (p>0.05) between groups I and II in functional scores and ROM (forward flexion, p=0.91; side external rotation, p=0.17; abduction external rotation, p=0.72; internal rotation, p=0.61). But we found that group II gained more flexion compared to group I at 3 months and 6 months (p<0.05) after the surgery. Conclusions: Both techniques of capsular release are effective for stiffness shoulder. However, the extended inferior capsular release shows superiority in forward flexion over anterior capsular release alone during 6 months of follows-up (level of evidence: Level I, therapeutic randomized controlled trial).

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.2
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• pp.79-91
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• 2020

Accurate assessment of greenhouse gas emissions is a cornerstone of every climate change response study, and reliable assessment of greenhouse gas emission data is being used as a practical basis for the entire climate change prediction and modeling studies. Essential, fundamental technologies for estimating greenhouse gas emissions include an on-site monitoring technology, an evaluation methodology of uncertainty in emission factors, and a verification technology for reductions. The closed chamber method is being commonly used to measure gas fluxes between soil-vegetation and atmosphere. This method has the advantages of being simple, easily available and economical. This study presented the technical bases of the closed chamber method for measuring methane fluxes from a rice paddy. The methane fluxes from rice paddies occupy the largest portion of a single source of greenhouse gas in the agricultural field. We reviewed the international and the domestic studies on automated chamber monitoring systems that have been developed from manually operated chambers. Based on this review, we discussed scientific concerns on chamber methods with a particular focus on quality control for improving measurement reliability of field data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1428-1438
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• 2013

Services take place in Internet environment, a formation of the trust relationship between user and service provider for services. Different authentication schemes such as using Certificate of Public Key Infrastructure authentication and using ID/PW for a simple user authentication have been proposed for trust relationship. In addition, in the case of electronic financial transactions, transaction integrity and non-repudiation features are provided. These services are provided in Internet environment, use various measures to ensure service safety. However, it was difficult to prevent attacks using existing security technology because of emergence of MITB attack that manipulate the memory area of the Web browser and social engineering attacks such as phishing/pharming, requires application of new security technologies became. In this paper, we propose a concept of smart secure-pad, and utilize it safely formed a trust relationship between user and service provider, a model has been proposed to ensure safety of data transmission. Proposed model's security evaluation results show security against to MITB attack and phishing/pharming that can't be prevent attack using existing security technology. In addition, service provider can easily apply the model in safe environment can provide Internet service using provided representative services applying the proposed model.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.430-430
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• 2007

In general, polyimides (PIs) are used in liquid crystal displays (LCDs) as alignment layer of liquid crystals (LCs). Up to date, the rubbing alignment technique has been widely used to align liquid crystals on the PI surface, which is suitable for mass-production of LCDs because of its simple process and high productivity. However, this method has some disadvantages. Rubbed PI surfaces include the debris left by the cloth and the generation of electrostatic charges during rubbing process. Therefore, rubbing-free techniques for LC alignment are strongly required in LCD technology. In this experiment, PI was uniformly coated on indium-tin-oxide electrode substrates to form LC alignment layers using a spin-coating method and the PI layers were subsequently imidized at 433 K for 1 h. The thickness of the PI layer was set at 50 nm. The LC alignment layer surfaces were exposed to an $Ar^+$ ion-beam under various ion-beam energies. The antiparallel cells and twisted-nematic (TN) cells for the measurement of pretile angle and electro-optical characteristics were fabricated with the cell gap of 60 and $5\;{\mu}m$, respectively. The LC cells were filled with nematic LC (NLC, MJ001929, Merck) and were assembled. The NLC alignment capability on ion-beam-treated PI was observed using photomicroscope and the pretilt angle of the NLC was measured by the crystal-rotation method at room temperature. Voltage-transmittance (V-T) and response time characteristics of the ion-beam irradiated TN cell were measured by a LCD evaluation system.

• Journal of radiological science and technology
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• v.28 no.2
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• pp.111-115
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• 2005

The quality of image from the system that creates medical images by using X-ray depends on the various different reasons such as the X-ray generator, the subject and the image transmission medium. In other words, thereare various factors existing that can influence on the quality of image from the moment when the X-ray is generated and until the final image is created. Therefore, the operator who creates images at the clinical site should make continuous evaluation and observation from the final image. There are various methods of evaluating the medical images, but it is assumed that the MTF measurement method can be suitable for measuring actual or effective resolution. So in this study, the MTF measurement method by using X-ray film has been avoided and the MTF features according to the deterioration of the X-ray system have been measured by using the software (the program used Borland C++ builder software and LEAD tools software) that can measure the MTF of the digital medical images. As the result of this measurement, it has been found out through the MTF graph that the resolution and sharpness from the old x-ray generator with a many years of using and many numbers of times of using were deteriorated for the quality of image comparing to those from the new system. Also a simple and easy measurement method for the MTF from the digital medical images can be obtained in this study.

• Journal of Korean Society of Steel Construction
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• v.26 no.1
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• pp.43-53
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• 2014

A single plate connection(SPC) consists of a plate welded to the columns and bolts connected to the beam web. The SPC is widely used for a simple shear connection of steel structure because it is easy-to-fabricated, easy-to-installed and economical. The conventional SPC is used for 2 to 12 bolts in a single vertical row. It is designed to limit the plate thickness by bolt diameter to obtain flexible and ductile connections. The design strength for eccentric shear shall be the lesser of the shear strength of bolts or bearing strength of plate and when the design strength is decided by edge distance failure, the results can be very conservative. Although the research on special solution for 'weak-plate/strong-bolt' model with 2 to 4 bolts has been conducted by L. S. Muir, and W. A. Thonton, 2004, study on generalized design procedures did not conduct. This study proposed design procedure for evaluation of the design strength of eccentric shear bolt groups on a single plate connection based on the actual edge distance and the direction of bolt reaction forces by using elastic vector method(EVM) and instantaneous center of rotation method(ICM).

• The Journal of Korean Society for School & Community Health Education
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• v.2 no.1
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• pp.41-52
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• 2001

The purpose of this research is to plan the activation of university health business through the appraisal of the function and role of university health centers. To be more specific: Firstly, analyze the facility, personnel, health service of the health centers, Secondly, appraise the role and function of the health centers, and Thirdly, consider the activation plans of health centers. The research method taken was the study of surveys conducted and written research materials on 5 women's universities in Seoul. These materials where descriptively analyzed by converting the surveys, facility and usage of health center and current personnel status in to percentage. The major results of the research are as follows: Unlike as stated in each university's additional clause on the number of personnel were working. This lack of specialized personnel resulted into lack of specialized and various services. Medicine for external application were stocked well whereas only simple medicine for internal application were on shelf and were issued only with a doctor's prescription. Universities with a full-time doctor had various available equipments. One university conducting dental treatment was equipped with indirect chest camera, dental X-ray, unit, chair(dental treatment chair) and even supersonic, electrocardiogram were available. In the case of D women's university, the number of beds compared to the number of students was lower than that of the other 3 universities, to the total size of the university was smaller than that of the other 3 universities. Among health prevention and care matters, health consultation was the only matter practised by all universities. Uniquely, there was one university that hosted epidemic prevention business. There are various tests given by each university, with each showing many differences, but some universities did not even conduct these tests. Vaccinations were usually being conducted through commission. All universities provided basic treatment, therefore matters concerning treatment at health centers were being conducted well. Concerning the management of equipment and documents, all the matters were being conducted except one university where instead of a student medical record, they were using a daily record. Because these were women's universities, most of the educations were on women's health. The subjects of these educations included: sex, contraception, prevention and control of tuberculosis, obesity, mouth hygiene, alcohol, geriatric disease, mental health and first-aid. The rate of health center usage is growing. Being women's universities, the service and treatment practised were mostly concerning sex education.