• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.2
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• pp.189-196
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• 2012

The heavy moderator acts as the ultimate heat-sink in an operating CANDU reactor. HUKINS has been developed to investigate moderator flow patterns. HUKINS consists of a 38.4-mm-thick cylindrical shell with a 0.95 m inner diameter and 88 sus-tubes that produce a total heat of 10 kW. A chemical visualization method was selected to estimate the occurrence of typical moderator flow patterns. Momentum-dominated flow, mixed flow, and buoyancy-dominated flow are detected under conditions of a heat load of 7.7 kW and input mass flow rates of 4, 7, and 11 L/min. The experimental results are similar to the results of a CFD simulation that consisted of approximately 1.9 million grids and was conducted using the k-${\varepsilon}$ turbulence model. Therefore, both the present experiments and simulations using HUKINS, a 1/8-scale model, represent all three important flow patterns expected in the real CANDU6 reference reactor. Thus, it has been demonstrated that HUKINS could be useful in the study of CANDU6 moderator circulation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.159-162
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• 2007

The characteristic of air-assist spray injected into subsonic crossflow were studied experimentally. External-mixing air assist injector of Orifice nozzle with L/d of 3 were tested with various air-liquid ratio. Shadowgraph photography was performed for spray visualization and trajectory of spray measurements. The detailed spray structure was characterized in terms of SMD, velocity, and volume flux, using PDPA. Experimental results indicate that penetration length was increased and spray distribution was accelerated by increasing air-liquid ratio.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.673-679
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• 2000

LNG Carriers are currently known as sole commercial means of shipping natural gas on the sea. They are designed to proven dangerous explosion for shipping a lot of gas over long distance. In this study. In this study, a scaled model chamber was made to investigate ventilation characteristics of the hood room in LNG carrier. Experimental study was performed in model using visualization equipments with laser apparatus and image intensifier CCD camera gated by an AOM controller Twelve different kinds of measuring area were selected as experimental condition. Instant simultaneous velocity vectors at whole field were measured by using 2-D PIV system which software adopts two-frame grey-level cross correlation algorithm. To look into stagnation area of hood room for LNG carrier, a three-dimensional numerical simulation with standard ${\kappa}-{\varepsilon}$ model was carried out by using PHOENICS for three kinds of Reynolds number, $6.5{\times}10^3$, $9.7{\times}10^3\;and\;1.29{\times}10^4$, based on the cavity inlet velocity and cavity height. The flow pattern showed the large scale counter-clockwise forced-vortex rotated at center area, small eddies at each corner and stagnation area located at left-back upper side of model.

• Korean Journal of Acupuncture
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• v.25 no.4
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• pp.167-174
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• 2008

Objectives : Acupuncture points and meridians have been usually depicted as a two dimensional drawing and verbal description. Recently, imaging and three-dimensional image processing technologies have been introduced into medical fields such as anatomy and virtual operation, for the purpose of enhanced efficiency in research and education. This study attempted an image modelling of the meridian and acupoint in the upper limb region. Methods : A vector image model of an arm was produced and medical information on the meridian and acupoint of the arm region was incorporated. Results : A 3D modelling of the acupuncture meridian and acupoint in the upper limb region was produced along with a user console to control the presentation of related information and to facilitate visualization of the 3D model images. Conclusions : A 3D modelling of the acupuncture meridian and acupoint will be an efficient platform for an education and research.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.815-816
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• 2009

Owing to the development of computer technologies, to process data derived from various sensors is recently demanding. It is also increasing to demand the moving object based servies like the services of location based and mobile application services. That's why it is needed the processing of visualizing the services for education aspects. In this paper, we show the implemented results about $R^*$ tree algorithm to insert, delete and search a object in two dimension environment.

• The Journal of the Acoustical Society of Korea
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• v.35 no.4
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• pp.288-294
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• 2016

The space between tire and wheel guard acts as a path for tire pattern noise transmission. In this study, acoustic phenomenon occurring in the tire-wheel guard space is investigated using acoustic mode analysis and visualization of the sound pressure distribution over the wheel guard surface. We introduced a cavity over the wheel guard surface to reduce the tire pattern noise, where the cavity acts as an acoustic damper. The interior noise was reduced by 2 dB(A), and the noise control measures treated in this study may provide an efficient method to improve interior sound quality without increasing cost and weight at the final stage of the vehicle development.

• KSBB Journal
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• v.27 no.1
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• pp.40-44
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• 2012

The laboratory animal group separation is dividing animal population into subgroups, which have similar average and standard deviation values among the subgroups, based on the biological characteristics such as body weight, glucose level in blood, etc. Although group separation is very important and initial step in experimental design, it needs a labor intensive process for researchers because of making similar average and standard deviation values among the subgroups using the raw biological characteristics. To reduce the labor cost and increase the efficiency of animal grouping, we developed a web program named as laboratory animal group separation (LAGS) program. This LAGS uses biological characteristics of population, number of group, and the number of elements per each subgroup as input data. The LAGS automatically separates the population into each subgroup that has similar statistical data such as average and standard deviation values among subgroups. It also provides researchers with the extraordinary data generated in the process of grouping and the final grouping results by graphical display. Through our LAGS, researchers can validate and confirm results of laboratory animal group separation by just a few mouse clicks.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.8
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• pp.62-69
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• 2010

Internal lathe machining with a boring bar is weak with respect to vibration because the bar is long and slender. Therefore, it is important to study the dynamic characteristics of a boring bar. The purpose of this study was to identify the effects of overhang and cutting conditions on the dynamic response characteristics of a boring bar. For an efficient experiment, an $L_g(3^3)$ orthogonal array was applied and the results were quantitatively analyzed by ANOVA. Overhang, feed per revolution, and depth of cut were selected as independent variables. Meanwhile, dynamic stiffness, damping ratio, damping coefficient, and acceleration were chosen as dependent variables. The vibration signal was obtained from an accelerometer attached to the boring bar, followed by visualization by a signal analyzer. The effect of overhang was found to have a significant effect on the dynamic stiffness, damping ratio, and damping coefficient, but the other variables did not. As the length of the overhang increased, the dynamic stiffness decreased and the damping ratio increased. In addition, the damping coefficient increased until the length of the overhang was 4D (where D is the shank diameter), after which it remained constant. The acceleration decreased until the overhang length was 4D, and then increased sharply when the overhang was increased further. From these results, the behavioral trend of the damping characteristics changed when its overhang length was 4D. Consequently, there is a critical point that the dynamic characteristics of boring bar change.

• Journal of the Korean School Mathematics Society
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• v.12 no.1
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• pp.71-97
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• 2009

The study was to develop the instruments including instructional materials and test items for enhancing spatial ability. A mixed methodology was chosen to achieve the purpose of the study. To find students' achievement, 5 units of instructional materials were developed through the qualitative method and test items were tested through the quantitative method with 152 of the 8th-graders. The strategies to develop the instructional materials were: firstly to focus on mathematics properties for developing spacial ability; secondly, to allow students to follow hierarchical procedure o[ mathematical properties from 2-d to 3-d; thirdly, to recognize what the manipulative can do and can not; and fourthly, to guide students tn develop the process oriented thought, not the result oriented thought. For the test, 25 items were analyzed to assess students' achievement using validity, difficulty, and discriminator.

• The Korean Journal of Pain
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• v.36 no.1
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• pp.98-105
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• 2023

Background: Ultrasound-guided first sacral transforaminal epidural steroid injection (S1 TFESI) is a useful and easily applicable alternative to fluoroscopy or computed tomography (CT) in lumbosacral radiculopathy. When a needle approach is used, poor visualization of the needle tip reduces the accuracy of the procedure, increasing its difficulty. This study aimed to improve ultrasound-guided S1 TFESI by evaluating radiological S1 posterior foramen data obtained using three-dimensional CT (3D-CT). Methods: Axial 3D-CT images of the pelvis were retrospectively analyzed. The radiological measurements obtained from the images included 1st posterior sacral foramen depth (S1D, mm), 1st posterior sacral foramen width (S1W, mm), the angle of the 1st posterior sacral foramen (S1A, °), and 1st posterior sacral foramen distance (S1ds, mm). The relationship between the demographic factors and measured values were then analyzed. Results: A total of 632 patients (287 male and 345 female) were examined. The mean S1D values for males and females were 11.9 ± 1.9 mm and 10.6 ± 1.8 mm, respectively (P < 0.001); the mean S1A 28.2 ± 4.8° and 30.1 ± 4.9°, respectively (P < 0.001); and the mean S1ds, 24.1 ± 2.9 mm and 22.9 ± 2.6 mm, respectively (P < 0.001); however, the mean S1W values were not significantly different. Height was the only significant predictor of S1D (β = 0.318, P = 0.004). Conclusions: Ultrasound-guided S1 TFESI performance and safety may be improved with adjustment of needle insertion depth congruent with the patient's height.