• Journal of the Korean Geotechnical Society
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• v.29 no.10
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• pp.49-56
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• 2013

The use of geothermal energy has been increased for economic and environmental friendly utilization. Ground thermal conductivity and borehole thermal resistance are very important parameters in the design of geothermal heat pump system. This paper presents an experimental study of heat exchange rate of U and W type ground heat exchangers (GHEs) measured by thermal performance tests (TPTs). U and W type GHEs were installed in a partially saturated dredged soil deposit, and TPTs were conducted to evaluate heat exchange rates under 100-hr continuous operation condition. The heat exchange rates were also calculated by analytical models to estimate borehole thermal resistances and were compared with experimental results. It comes out that multi-pole and equivalent diameter (EQD) models resulted in more accurate agreement than shape factor (SF) model which is currently more often used.

• Journal of Energy Engineering
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• v.11 no.3
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• pp.237-246
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• 2002

If the safety depressurization system of APR-1400, the Korean next generation reactor, is in operation, water, air and steam are successively discharging into a in-containment refueling water storage tank through spargers. Among the phenomena occurring during the discharging processes, the air bubble clouds produce a low-frequency and high-amplitude oscillatory loading, which may result in the most significant damages to the submerged structures if the oscillation frequency is the same or close to the natural frequency of the structures. The involved phenomena are so complicated that most of the prediction of frequency and pressure loads has been resorted to experimental work and computational approach has been precluded. This study deals with a numerical simulation on the behavior of air bubble clouds discharging into a water pool through a sparger, by using a commercial thermal hydraulic analysis code, FLUENT, version 4.5. Among the multiphase flow models, the VOF (Volume Of Fluid) model was selected to simulate the water, air and steam flows. A satisfactory result was obtained comparing the analysis results with the ABB-Atom test results which had been performed for the development of sparser.

• Journal of Energy Engineering
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• v.18 no.3
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• pp.147-155
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• 2009

Demand for distributed source by new and renewable energy has been gradually increasing recently. For the characteristics of distributed generation, distributed source is located near the distribution system and customers' buildings and can be operated in standalone mode or in interface mode with distribution system. When the distributed sources are interfaced with distribution system, the standard for interfacing distributed source with existing distribution system and operation manual should be updated with revisions in order to manage the distributed source effectively and operate the distribution system stably because how to operate the interfaced system is different from that of existing distribution system. In this paper, the FEP(Front End Processor) using the international standard protocol IEC-60870 for interfacing with distributed resources was designed. The designed system was verified via the test result using main control system for distributed generation and RTU(Remote Terminal Unit) for interface with distributed power generating.

• Journal of Korean society of Dental Hygiene
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• v.19 no.6
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• pp.1037-1046
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• 2019

Objectives: This study was conducted to test the critical thinking tendency, clinical practice satisfaction, and clinical performance, and analyze the factors impacting clinical practice satisfaction and clinical performance of dental hygiene students. Methods: The study conducted a written survey during the period between 30 July ~20 August 2019, among 3rd and 4th year dental hygiene students from Seoul, Gyung-gi region, who had taken clinical practice courses. Using SPSS 22.0 program (IBM SPSS statistics, New York, USA), the study analyzed the final 174 cases. Results: Dental hygiene students scored 3.33±0.43, 3.48±0.83, and 3.30±0.58 for critical thinking, clinical practice satisfaction, and clinical performance, respectively. The clinical thinking score was higher when their study performance was good (p<0.001), clinical practice satisfaction was higher when their major satisfaction was satisfactory (p<0.001), higher when their relationship with their clinical practice partner was good, and the clinical performance was better when the students' major satisfaction was good (p<0.001). The study performance yielded better results when their study achievement was better (p<0.05). Clinical practice satisfaction (r=0.156) and clinical performance (r=0.393) showed a positive correlation with critical thinking, and clinical performance had a positive correlation with clinical practice satisfaction. The impact factor for clinical practice satisfaction appeared to be clinical performance (p<0.05) and major satisfaction (p<0.001), and the factors impacting the clinical performance were among the sub-causes of critical thinking (p<0.05), intellectual fairness (p<0.05), watchfulness (p<0.05), clinical practice satisfaction (p<0.05), and major satisfaction (p<0.01). Conclusions: Results of the study showed that for dental hygiene students, critical thinking, clinical practice satisfaction, clinical performance, and major satisfaction were the impact factors affecting the students' clinical performance. Therefore, the study recommends that development of educational programs and operation of a field-based curriculum is necessary to improve critical thinking, clinical practice satisfaction, and major satisfaction.

• Korean Journal of Head & Neck Oncology
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• v.11 no.1
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• pp.3-8
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• 1995

Tuberculous cervical lymphadenitis is one of common cause of neck mass in young adult in Korea. Tuberculous cervical lymphadenitis known as scrofula was being treated by the 'Royal Touch' in the 5th century and by surgery in the 17th century, yet the principle of the treatment is still controversal. We report the clinical evaluation and therapeutic result about 121 tuberculous cervical lymphadenitis. The result were as follows: 1) The annual incidence(1985-1994) was 30.5 % (37 cases: 1985-1986), 17.7 % (21 cases: 1990-1992). 19.8%(24 cases: 1994). 2) The age of highest incidence was 20-29 year old age group in 41.3% (50 cases) and female predominated over male by 1.8 : 1. 3) The duration of disease was less than 6 months, in 85.9% (104 cases). 4) The most commonly involved LN group was superficial cervical group in 69.4% (84 cases), and difference between Rt & Lt, was not significant. 5) The most common symptom and local finding(P/E) were, painless swelling of LN in 74.3 % (90 cases) and single mass in 59.5 % (72 cases). 6) In seasonal variation, 85.9% (104 cases) was spring and summer. 7) Procedures except biopsy for evaluation were chest PA, AFB smear & culture(sputum), Mantoux test, USG, CT and, Associated extracervical tuberculous lesions were lung, axilla, breast. 8) In operation method (involving biopsy), Excision was 68.5 % (83 cases), neck dissection was 6.6% (8 cases). 9) The Modality, Duration and side effect of antituberculous medication: INH-Rifampin­Ethambutol was 66.1 % (88 cases), duration was 1 year in 84.3% (102 cases), side effects were severe GI trouble (24.8%), liver function damage (3.3%). 10) 3 cases recurred on the same site after 2 yrs(2 cases) and 4 months(1 case) and its treatment was curretage or I & D, with antituberculous medication.

• Information Systems Review
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• v.7 no.2
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• pp.1-21
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• 2005

Integrated Railroad Information System(IRIS) Construction Project is one of the super projects in Korea required to invest over 100 billion won and 10,000 engaged manpower until Dec 30, 2004. Composition of this paper is as follows; firstly, examined individual contents and aspects of IRIS, and studied formality and contents that have been based to project methodology for successful propulsion of project in overall situation of SI project progress until present. Secondly, presented for construction background of IRIS as well as Project Management and Project Development Methodologies. Thirdly, described each characteristic and development substance for individual systems after present whole contents and system image of the system. Finally, presented successful propulsion result of this project and development directions. We presented development example laying stress on IRIS's Project contents and propulsion circumstances. Evaluation about operation results should be analyzed and studied in detail operating system from now on.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.490-497
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• 2017

The Main Landing Gear(MLG) of Rotary Wing Aircraft is an essential equipment in Landing System for pilot to perform a flight mission. It supports the fuselage at ground and absorbs the impact from the ground when landing, thereby, these functions sustain operational capability for pilot and crew. However, the A aircraft caused asymmetry and leakage hydraulic when it was stationed on the ground. Therefore, this paper summarizes pilot comments in operation which are classified by cause of occurrence and the troubleshooting process about each comment. It also describes design improvements which was derived from troubleshooting and suggests verification results of flight test.

• School Mathematics
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• v.9 no.2
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• pp.223-240
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• 2007

The purpose of this study was to investigate the degree to which the middle school mathematics curriculum matched the item difficulty levels of representative mathematics items. The items used in this study were developed for the National Assessment of Educational Achievement. Ranks for difficulty values of the 60 multiple-choice item were calculated via both Classical Test Theory and Item Response Theory and correlated with the rank order of the mathematics content and cognitive domains sequence. There are six content domains; number and operation, algebra, measurement, figure, pattern and function, and probability and statistics. The cognitive domains include computation, understanding, reasoning and problem-solving. Results suggest a congruence between cognitive domain's sequence and item difficulty levels of items based on that sequence. This finding indicates that the linear or hierarchical assumptions concerning the sequence appears to be reasonable. The characteristics of items that were exceptions to this trend were addressed.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.1
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• pp.41-48
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• 2016

Motor evoked potential of spinal surgery is known to cause damage due to the movement path of the continuous scan operation and surgery can be performed with minimized disability after surgery. However, if it is not at all formed at the wave motion evoked potential can occur during surgery and, in some cases the size of the waveform to be measured is very small and intermittent. In this case, the surgery cannot provide information about whether there is neurological damage. Increased intensity of the wave-induced motion of the dislocation does not occur if it appears in a very small amplitude stimulus, but changing the inspection area that electrical stimulation of the waveform changes could not be found. However, stimulation of a wide area in the cerebral cortex was found to occur with a waveform in the patients who underwent examination. Through this study, we propose a useful motor evoked potential test. From November to December 2015 three spine surgery patients visited Samsung Medical Center as neurosurgery patients with omission discomfort, gait disturbance, and no symptom of strength before surgery. In spine surgery patients with motor grade weakness, when motor evoked potential waveform has not been measured, in examination of the site of electrical stimulation of the cerebral cortex from entering the C3+C5/C4+C6 or C3+C1/C4+C2 if by the activity of more motor neuron unit, it was found that the waveform is better formed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.3
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• pp.246-254
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• 2018

In this study, we developed a thermoelectric generation system for coastal fishing boats that allows for a high-density arrangement of thermoelectric modules, verified the improvement in performance by conducting comparative analysis between field test results and results from previous studies. The developed thermoelectric generation system was installed in a 3-ton gill-netter to analyze the engine revolutions per minute and energy production per day for each fishing process over a period of 20 days. From the experimental results, the maximum electric energy generated was 207.1 Wh, the minimum was 53.93 Wh and the average electric energy was 129.98 Wh. In accordance with the increasing of the engine r.p.m., the maximum electric production was 183 W at 1,500 r.p.m. It was approximately 80.5% of designed capacity, 227.2 W. Considering the result in the earlier research was 50.7% of designed capacity, 115.8 W. It was improved by 30% compared to the earlier one. The fishing operation was classified as departure, fishing and arrival. From the result on production analysis of electric energy, the composition of energy was 63% in fishing, 19.5% in departure and 17.5% in arrival. The electric energy production per unit hour was 42.8% in arrival, 32.9% in departure and 24.3% in fishing.