• KIEAE Journal
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• v.17 no.2
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• pp.5-12
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• 2017

Purpose: Under the purpose of presenting the adequate remodeling period for the improvement of thermal insulation performance of external walls in deteriorated buildings, the change in external wall and residential environment problem(dew condensation) due to aged deterioration after the apartments were constructed in Korea were analyzed. Method: Temperature Difference Ratio Outside(TDRo) and Heat Flow Meter(HFM) were used as measurement methods to evaluate the thermal insulation performance of deteriorated buildings. For TDR evaluation, thermo-graphic camera was used to measure and analyze the surface temperature of external wall. Also, dew condensation evaluation was analyzed using the Temperature Difference Ratio Inside(TDRi). Result: As a result of analyzing thermal performance through TDRo, the first decline point of thermal insulation performance began after 14-16 years have passed since construction was completed, and after 20 years have passed the decline point of thermal insulation performance reappeared. As a result of analyzing U-value with HFM measurement method, the decline rate of external wall's thermal insulation performance is lower than 2% in average at around 5 years after completion, and 8.7% in average at 10-15 years, and over 10.2% in average at 20 years.

• Structural Engineering and Mechanics
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• v.66 no.2
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• pp.273-283
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• 2018

Currently, the dynamic amplification effect of suction is described using the wind vibration coefficient (WVC) of external loads. In other words, it is proposed that the fluctuating characteristics of suction are equivalent to external loads. This is, however, not generally valid. Meanwhile, the effects of the ventilation rate of louver on suction and its WV are considered. To systematically analyze the effects of the ventilation rate of louver on the multi-dimensional WVC of ultra-large cooling towers under suctions, the 210 m ultra-large cooling tower under construction was studied. First, simultaneous rigid pressure measurement wind tunnel tests were executed to obtain the time history of fluctuating wind loads on the external surface and the internal surface of the cooling tower at different ventilation rates (0%, 15%, 30%, and 100%). Based on that, the average values and distributions of fluctuating wind pressures on external and internal surfaces were obtained and compared with each other; a tower/pillar/circular foundation integrated simulation model was developed using the finite element method and complete transient time domain dynamics of external loads and four different suctions of this cooling tower were calculated. Moreover, 1D, 2D, and 3D distributions of WVCs under external loads and suctions at different ventilation rates were obtained and compared with each other. The WVCs of the cooling tower corresponding to four typical response targets (i.e., radial displacement, meridional force, Von Mises stress, and circumferential bending moment) were discussed. Value determination and 2D evaluation of the WVCs of external loads and suctions of this large cooling tower at different ventilation rates were proposed. This study provides references to precise prediction and value determination of WVC of ultra-large cooling towers.

• Bulletin of the Korean Mathematical Society
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• v.53 no.5
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• pp.1497-1530
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• 2016

External barrier options are two-asset options with stochastic variables where the payoff depends on one underlying asset and the barrier depends on another state variable. The barrier state variable determines whether the option is knocked in or out when the value of the variable is above or below some prescribed barrier level. This paper derives the explicit analytic solution of the chained option with an external single or double barrier by utilizing the probabilistic methods - the reflection principle and the change of measure. Before we do this, we examine the closed-form solution of the external barrier option with a single or double-curved barrier using the methods of image and double Mellin transforms. The exact solution of the external barrier option price enables us to obtain the pricing formula of the chained option with the external barrier more easily.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.4
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• pp.393-404
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• 2003

Statement of problem. Higher incidence of prosthetic complications such as screw loosening, screw fracture has been reported for posterior single tooth implant. So, there is ongoing research regarding stability of implant-abutment interface. One of those research is increasing the implant diameter and prosthetic table width to improve joint stability. In another part of this research, internal conical type implant-abutment interface was developed and reported joint strength is higher than traditional external hex interface. Purpose. The purpose of this study is to compare stress distribution in single molar implant between external hex butt joint implant and internal conical joint implant when increasing the implant diameter and prosthetic table width : 4mm diameter, 5mm diameter, 5mm diameter/6mm prosthetic table width. Material and method. Non-linear finite element models were created and the 3-dimensional finite element analysis was performed to see the distribution of stress when 300N static loading was applied to model at $0^{\circ},\;15^{\circ},\;30^{\circ}$ off-axis angle. Results. The following results were obtained : 1. Internal conical joint showed lower tensile stress value than that of external hex butt joint. 2. When off-axis loading was applied, internal conical joint showed more effective stress distribution than external hex butt joint. 3. External hex butt joint showed lower tensile stress value when the implant diameter was increased. 4. Internal conical joint showed lower tensile stress value than external hex butt joint when the implant diameter was increased. 5. Both of these joint mechanism showed lower tensile stress value when the prosthetic table width was increased. Conclusion. Internal conical joint showed more effective stress distribution than external hex joint. Increasing implant diameter showed more effective stress distribution than increasing prosthetic table width.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.1
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• pp.79-84
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• 2008

We are developing a small-sized high temperature superconducting magnetic energy storage (HTS-SMES) magnet with the nominal storage capacity of 600 kJ, which provides electric power with high quality to sensitive electric loads. Critical current and N-value of a high temperature superconductor with large current, which was selected for the development of the 600 kJ HTS-SMES magnet, were investigated in various oblique external magnetic fields. Based on the critical current and N-value measured for the short sample conductor, we discussed the DC V - I characteristic of a model coil fabricated with the same conductor of 500 m. The results show that the measured critical current and N-value of the conductor for parallel field are constant in external magnetic fields less than about 0.2 T. However, for oblique fields, its critical current and N -value abruptly decrease in all external magnetic fields. Moreover, the measured critical current of the model coil well agrees with the numerically calculated one based on the DC V - I characteristic measured for the short sample conductor. This suggest that losses and critical currents for an HTS-SMES magnet made up of a high temperature superconductor with anisotropic characteristic are predictable from the data of a short sample conductor.

• Journal of Digital Contents Society
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• v.12 no.3
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• pp.339-345
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• 2011

The k-means has been one of the popular, simple and faster clustering algorithms, but the right value of k is unknown. The value of k (the number of clusters) is a very important element because the result of clustering is different depending on it. In this paper, we present a novel algorithm based on an external cluster relationship criterion which is an evaluation metric of clustering result to determine the number of clusters dynamically. Experimental results show that our algorithm is superior to other methods in terms of the accuracy of the number of clusters.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.4
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• pp.617-625
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• 2002

At present in many cases the methods of medical treatment in Oriental medicine Korea lays emphasis on internal use, but to improve the curative value and for the diversity of medical treatment it is desperately needed to study external medical treatment more deeply. From the viewpoint of medical science history, as various additives and new discoveries are developed this has made it easy to use and improved the curative value of it ; thus external medical treatment has been rapidly progressed both in quality and quantity. Therefore, in studying the external medical treatment, it is very important to know it's history. So, I intend to study the early external medical treatment first. The external medical treatments mentioned in the Mawangtew medical books (52Byeongbang, Yangsangbang, Japryobang, Taesanseo), Hwangjenaekyeong, and Geumgweyoryak which were written or presumed to be written in early times were examined to study the early external medical treatments. The parts of body or diseases in which external medical treatments were applied; the methods of external application and the administration of medicine; the number of prescriptions, and the herbs used are also examined. I came to the following conclusions as I compared the kinds of books with the itemized lists based on the results of examination. 1) Though Mawangtew medical books (52Byeongbang, Yangsangbang, Japryobang, Taesanseo) was written earlier than Hwangjenaekyeong and Geumgweyoryak, there are more incidents of the disease in which external medical treatments were applied, the methods of external application and the administration of medicine, the kinds of prescriptions , and the different herbs used in Mawangtew medical books than in Hwangjellaekyeong and Geumgweyoryak. 2) In the six medical books mentioned above there are more prescriptions for external diseases and dermatitis than for internal diseases. 3) From the viewpoint of the number of prescriptions, the most frequent use of a medicine type was a natural type of medicine. The second was ointment type, and the third was liquid type. A powder type was the fourth. 4) In the administration of medicine, combination types such as both pasting and plastering were used most frequently. 5) Vegetable, mineral and animal nature herbs were used diversely for the early external medical treatments. Things such as wine and vinegar were also used as a herb.

• The Journal of Korean Society for Radiation Therapy
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• v.14 no.1
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• pp.35-39
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• 2002

Introduction : It is essential to input patients external contour in 3D treatment plan. We would like to see changes in depth and dose when 3D RTP is operating auto contouring when windows value (Width/Level) differs in this process. Material & Methode : We have analyzed the results with 3D RTP after CT Scanning with round CT Phantom. We have compared and analyzed MU values according to depth changes to Isocenter changing external contour and inputting random Window value. We have watched change values according to dose optimization in 4 directions(LAO, LPO, RAO, RPO), We plan 100 case for exact analyzation. We have results changing window value random to each beam in 100 cans. Result : It showed change between minimum and maximum value in 4 beam is Depth 0.26mm, MU $1.2\%$ in LAO. It showed LPO-Depth 0.13mm, MU $0.9\%$, RAO-Depth 0.2mm MU $0.8\%$, RPO-Depth 0.27mm, MU $1.1\%$ Conclusion : Maximum change in depth 0.27 mm, MU error rate is $0.12\%$ according to Window change. As we can see in these results, it seems Window value change doesn't effect in treatment. However, it seems there needs to select appropriate Window value in precise treatment.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.321-326
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• 2000

This study was performed to analyze the variation of inside temperature of greenhouse according to shading methods. We used two shading method of external and internal method. The shading effect of external screen was superior to internal screen. Soil temperature of greenhouse without screen was higher than outside soil temperature, but the value of greenhouse with internal and external screen was lower than outside.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.2
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• pp.151-164
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• 2007

Criteria for rehabilitation priority are discussed to evaluate structural stability of deteriorated water transport and transmission pipes, in this study. For the purposes, safety factor is introduced and estimated by measuring tensile strength and by analyzing stress caused by the internal-external loads working on buried pipe body. Related informations are surveyed and collected under various conditions in the fields by digging out and the structural stability is assessed. In the evaluation results of structural safety, it is shown that steel pipe is more affected by external load than internal load. The average external load is estimated as $53.7kg/cm^2$ and total hoop stress is estimated by $2676.5kg/cm^2$. Also, Poisson effect into longitudinal direction due to internal and external loads is most influential on hoop stress. The calculated safety factors of hoop stress are ranged from 0.7 to 5.2 with average value of 2.1, considering a bending stress to longitudinal direction. The decision of rehabilitation priority by safety factors show that structural safety of CIP sample 1(S1) was assessed at the lowest order with safety factor value, 0.7 and that of DI sample 15(S15) was evaluated as the most stable in structural aspect.