• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.235-236
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• 2002

A Klystron powered dual photon energy electron linear accelerator 2300 C/D from Varian Associates has been installed in our center. From the radiological safety view as well as treatment planning, the output (contamination) of Bremsstrahlung Radiation with electron beam energy determined accurately. It has been found 0.5% to 4.7% with increasing the electron beam energy which is the clinically not much significant in the treatment of the malignant diseases with the treatment of electron beam.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.20-27
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• 2009

This paper presents an analytic study for replacement of the ballast track in existing subway bridge by the Precast slab panel(B2S) track. To evaluate the dynamic responses on application of B2S track, the time history analysis with the 3D modeling. A total of two models, which were one ballast track bridge and B2S track bridge, were used in the FE analysis. The results of this study show that the dynamic displacement and acceleration of the B2S track bridge were significantly reduced for a higher train speed, compared to the ballast track bridge. Also, the replacement of the ballast track bridge in existing subway bridge by the B2S track increased the structural safety of bridge and ensured sufficient dynamic stability and serviceability. As a result, the servicing subway bridge with B2S track system has need of the reasonable measures which could be reducing the static and dynamic response and improving the performance.

• Quality Improvement in Health Care
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• v.25 no.2
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• pp.2-15
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• 2019

Purpose: The purpose of this study is to provide basic data for the development of the most appropriate and effective educational materials for patients and their caregivers through the educational experiences of patient safety officer. Methods: This study is a qualitative analysis that involves using the focus group interview to understand the patient safety education experience of the patient safety officer. Results: The patient safety education experience of the patient safety officer is divided into four topics: (1) patient safety education content (2) patient safety education method (3) patient safety education status (4) activation and improvement of patient safety education. Additionally, the study incorporated twelve subtopics: (a) falls (b) speak up (c) patient safety campaign (d) patient safety rounding and a one on one training (e) education through medical staff (f) education using broadcast, video, post, among others (g) a lot of education in patient (h) patients not interested in patient safety education (i) patient safety education is less effective (j) human and medical expenses support (k) provision of standardized educational materials (l) patient safety culture for patient participation. Conclusions: This study indicate that education for patients and the caregivers should be inclusive and protective of stakeholders from the risks involved in patient safety events. The experience of patient safety officer is necessary for patient safety education for both patients and the caregivers since it is the source of basic data for the future development of patient safety education.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1766-1769
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• 2005

Air-operated valve(AOV) is one of principal valves that are using to control fluid flow in nuclear power plants. AOV is suffered from damage and malfunction by the abrasion, corrosion and vibration of valve parts under the long time operation. This mechanical trouble and malfunction of valve is critical for the safety of power plant. So a periodic diagnosis for safety of power plants is inevitable to guarantee the safety of the power plant. But depending on the type of the actuator and valve body, various types of AOV exist. In this study, It is developed the diagnostic system that users of power plants are easy to handle in this paper.

• Journal of Korean Institute of Fire Investigation
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• v.4 no.1
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• pp.62-69
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• 2004

The purpose of this study on the sheath heater having high occurrence of fires in a small work place because of not having the safety device, was to find out the characteristics required in the field examination of the fires in the courses of investigation. The results of the experiments conducted and reviewed on the basis of the fire cases whose conditions of the ignition possibility were divided into A, E, C and D are as follows: When the sheath heater without safety device is left on the condition of the heat accumulation of which the temperature rapidly rise, and then ignite the inflammables of the surroundings. In such cases, it was characterized that the color change trace appeared even if no short trace was discovered in the power line.

• Journal of Navigation and Port Research
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• v.28 no.3
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• pp.207-211
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• 2004

The final goal of this research is to establish the relative dangerousness D/B for factors on seakeeping performance. This D/B is essential to develope the seakeeping performance evaluation system built-on-ship. The system is composed of the apparatus for measuring a vertical acceleration to be generated by the ship's motions, computer for calculating the synthetic seakeeping performance index and monitor for displaying the evaluating diagram of navigational safety of ship. In this paper, a methodology on the establishment of the relative dangerousness D/B for factors on seakeeping performance is presented by a numerical simulations, playing an important role on the algorithm of the program for calculating the synthetic seakeeping performance index. Finally, It is investigated whether the relative dangerousness D/B can be realized an accurate values according to the loading conditions, weather conditions, wave directions end present ship's speed of a model ship.

• Journal of the Korean Geotechnical Society
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• v.25 no.12
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• pp.69-85
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• 2009

It is very important to measure reliable dynamic properties of each zone in dam for seismic design. However, the Vs values of core and rock-fill zone are seldom determined by field test. Consequently, seismic design in dam is performed using Vs values assumed or empirically determined. So, it is required that reliable Vs has to be evaluated by in-situ test. In this study, surface wave method, which is nondestructive, was applied to dam to evaluate Vs profiles of core and rock-fill zone in dam. In 6 dams, using SASW and HWAW methods, Vs profiles were evaluated reliably. D/B of Vs profiles of each zone with depth and relationship between confining pressure and Vs profiles of rock-fill zone were constructed including existing results of other dams. The evaluated D/B and proposed relationship were compared with the frequently used empirical method by Sawada and Takahashi.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.765-771
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• 2019

With the increase in the speed of ships and the size of ocean structures, the importance of flow noise has become increasingly critical in meeting regulatory standards. However, unlike active investigations in aeroacoustics fields for airplanes and trains, which are based on acoustic analogy methods for tonal and broadband frequency noise, only the discrete blade passing frequency noise from propellers is considered in marine fields. In this study, prediction methods for broadband noise in marine propellers and underwater appendages are investigated using FW-H Formulation1B, which can consider the mechanism of primary noise generation of trailing edge noise. The original FW-H Formulation 1B is based on the pressure correlation function tolackitsgeneralityandaccuracy. To overcome these limitations, wall-pressure spectrum models are adopted to improve the generality in fluid mediums. The comparison of the experimental results obtained in air reveals that the proposed model exhibits a higher accuracy within 5 dB. Furthermore, the prediction procedures for broadband noise for hydrofoils are established, and the estimation of broadband noise is conducted based on the results of the computational fluid dynamics.

• Korean Chemical Engineering Research
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• v.62 no.4
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• pp.327-334
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• 2024

The risks associated with coal dust explosion were investigated by analyzing various characteristics affecting the possibility of explosion. Samples were collected directly from two regions of the transfer process where the most explosions occurred in coal-fired power plants, and the composition ratio and average particle diameter that could affect the experiment were considered. As experimental items, explosion intensity, particle size and distribution, moisture content, dust concentration, minimum ignition energy, minimum ignition temperature, and oxygen concentration that affect the explosion were evaluated. As a result, the explosion intensity was found to have a maximum explosion pressure of 7.1 bar at a dust concentration of 500 g/m³ in sample A, and the maximum explosion pressure increase rate was 366 bar/s. In terms of dust particle diameter and particle size distribution, sample A had an average diameter of 35 ㎛ (D 50%), which was smaller than sample B. The moisture content was 5.7% in sample A, which was more than twice as high as 2.5% in sample B. The minimum explosion concentration was 400 g/m³ in sample A, which was lower than 2,000 g/m³ in sample B, so it had a risk. Since neither sample exploded at 1,000 mJ, it is judged that if the minimum energy is 500 mJ or higher, it can be regarded as dust with a low sensitivity to ignition compared to similar previous studies. The minimum ignition temperature was 532℃ in sample A and 634℃ in sample B, so sample A was more dangerous than sample B. The marginal oxygen concentration was 18.0% in both samples, so it is judged that there is a constant risk of explosion in the atmosphere.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.6
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• pp.638-643
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• 2013

Nowadays, the hydraulic power unit (HPU) has been increased its working pressure and enlarged its capacity in order to improve the performance of the hydraulic system, but it produces noise leveled around 110dB(A) during operation. Recently, due to the reinforcement of industrial safety regulations and the requirement of improving work environment, a separated HPU room is installed at outside or underground of the building as to reduce the noise from HPU, but there are also problems of power loss owing its fluid friction of pipe system and of deficient accessibility during its failure accident. In this study, experiment is performed to improve the noise characteristics with installing a soundproof chamber to minimize the power loss and exclude effectively the high leveled noise, which is generated during the power conversion of HPU.