• Journal of Industrial Technology
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• v.21 no.B
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• pp.281-286
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• 2001

In this study, product design and prototype manufacturing of a plastic water-pump pulley has been tried. The designed model is supposed to be made of 33 % glass reinforced resin of which the tensile strength is 180 MPa, and has 24 ribs on each side to increase its structural strength. Structural analysis under a static load of 300 kgf acting on both edges of the belt has been carried out using a commercial finite element code, MARC. The analysis result showed the maximum effective stress near a rib of designed model would be at most 35 MPa (less than 20% of the tensile strength), therefore, the plastic product would be sufficiently safe under that loading condition. On the basis of the structural analysis, a prototype of the designed model has been manufactured by using the fused deposition modelling (FDM) method which is one of the rapid prototyping (RP) methods, using ABS resin and support materials. The CAD data exported to the RP system in STL format was prepared by a commercial solid modeling software, SolidWorks. It has been proved that the plastic pulley can successfully replace the existing flow-formed steel product.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.1
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• pp.33-40
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• 2012

The scaffold serves as 3D substrate for the cells adhesion and mechanical support for the newly grown tissue by maintaining the 3D structure for the regeneration of tissue and organ. In this paper, we proposed integrated scaffold fabrication system using multi-axis rapid prototyping (RP) technology. It can fabricate various types of scaffolds: arbitrary sculptured shape, primitive shape, and tube shape scaffolds by layered dispensing biocompatible/ biodegradable polymer strands in designated patterns. In order to fabricate the 3D scaffold, we need to generate the plotting path way for the scaffold fabrication system. We design a data processing program - scaffold plotting software, which can convert the 3D STL file, primitive and tube model images into the NC code for the system. Finally, we fabricated the customized 3D scaffolds with high accuracy using the plotting software and the fabrication system.

• Journal of Chest Surgery
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• v.18 no.2
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• pp.157-164
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• 1985

Our series comprised 68 patients of ventricular septal defect who underwent open heart surgery at the Department of Thoracic and Cardiovascular Surgery, School of Medicine, Kyungpook National University, from January, 1980 to September, 1984. Of the 68 patients, 47 patients were male [69.1%] and 21 patients were female [30.9%]. Their age ranged from 3 years to 27 years, and the mean age was 10.1 years. Upon Kirklin`s anatomical classification, type I constituted 29.4%, type II 69.1%, type III 1.5%, and type IV 1%. The cardiac anomalies associated with ventricular septal defect were 21 in all; 5 PS, 4 Aortic insufficiency, 2 ASD, 4 Patent foramen ovale, and 1 Patent ductus arteriosus. Upon the data of cardiac catheterization, most of the patients had Qp/Qs of 1.4-1.8, Pp/Ps of 0.25 or less and Rp/Rs of 0.25 or less. There was no significant correlationship between the rate of operative complication & mortality and the increase of Qp/Qs, Pp/Ps, and Rp/Rs. The values of Qp/Qs, Pp/Ps and Rp/Rs were correspondingly increased according to increment of the defect size. 20 patients developed postoperative complications, such as 4 acute respiratory failure, 3 reexploration due to massive bleeding, 1 low cardiac output, 1 patch detachment, and 2 air embolism. Operative mortality rate was 7.4% [5 cases] among 68 patients.

• Journal of Chest Surgery
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• v.17 no.3
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• pp.339-345
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• 1984

Thirty four patients with a ventricular septal defect, aged 2 months to 24 years [median 2.33 years], had lung biopsies during open heart procedures to assess the degree of pulmonary vascular disease. The patients were divided into two groups according to their age; group 1 - under 2 years of age [15 patients], and group 2- over 2 years of age [19 patients]. The, pathologic change of the pulmonary arterioles was correlated with pre-operative hemodynamic data in 34 patients. There was no significant correlation between the severity of pulmonary vascular disease according to Heath-Edwards classification and the patients age [X2=1.8381, P=0.1751 ]. There was a significant correlation between degree of medial wall thickness and arteriolar diameter and the level of preoperative peak pulmonary artery pressure and peak systemic artery pressure [Pp/Ps]. Also, there was a good correlation between the preoperative pulmonary vascular resistance and systemic vascular resistance [Rp/Rs]. There was no significant correlation between wall thickness and Pp/Ps, and Rp/Rs below the age of 2 years. We conclude that, in patients over 2 years of age, there was a significant correlation between the medial wall thickness of the pulmonary arteriole and elevation of Pp/Ps and Rp/Rs. This is not true in patients under 2 years of age.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.1
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• pp.37-41
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• 2001

HPLC separation of ionic samples tends to be more complicated and difficult to understand than that of non-ionic compounds. On the other hand, band spacing is much more easily manipulated for ionic than for neutral samples. Ion-suppression RP-HPLC method was used with organic modifier and aqueous buffer solution. In this work, five mononucleotides of cytidine-5-monophosphate (5-CMP) disodium salt, uridine-5-monophosphate disodium salt (5-UMP), guanosine-5-monophosphate disodium salt (5-GMP), inosine-5-monophosphate disodium salt (5-IMP), and adenosine-5-monophosphate disodium salt (5-AMP) were examined. Acetic acid and sodium phosphate were used as buffers, and methanol as an organic modifier. A new relationship between the retention factor and the buffer concentration at a fixed modifier content (5% of methanol) could be expressed by following: K = (k(sub)-1 + k(sub)0 (k(sub)B/k(sub)S)/(1 + (k(sub)B/k(sub)S) C(sub)B(sup)a), where C(sub)B was the concentration of buffer. Using this relationship, the calculated values closely matched the experimental data. The derived relationship showed that as the buffer concentration increased, the retention factor approached a certain value, and this was buffer dependent.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.6
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• pp.146-153
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• 2010

For the indoor location, wireless fingerprinting is most favorable because fingerprinting is most accurate among the technique for wireless network based indoor location which does not require any special equipments dedicated for positioning. As fingerprinting method,k-nearest neighbor(KNN) has been widely applied for indoor location in wireless location area networks(WLAN), but its performance is sensitive to number of neighborsk and positions of reference points(RPs). So possibilistic fuzzy c-means(PFCM) clustering algorithm is applied to improve KNN, which is the KNN/PFCM hybrid algorithm presented in this paper. In the proposed algorithm, through KNN,k RPs are firstly chosen as the data samples of PFCM based on signal to noise ratio(SNR). Then, thek RPs are classified into different clusters through PFCM based on SNR. Experimental results indicate that the proposed KNN/PFCM hybrid algorithm generally outperforms KNN and KNN/FCM algorithm when the locations error is less than 2m.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.2
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• pp.125-133
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• 2011

For any pattern matching based algorithm in WLAN environment, the characteristics of signal to noise ratio(SNR) to multiple access points(APs) are utilized to establish database in the training phase, and in the estimation phase, the actual two dimensional coordinates of mobile unit(MU) are estimated based on the comparison between the new recorded SNR and fingerprints stored in database. As fingerprinting method, k-nearest neighbor(KNN) has been widely applied for indoor location in wireless location area networks(WLAN), but its performance is sensitive to number of neighbors k and positions of reference points(RPs). So intuitive fuzzy c-means(IFCM) clustering algorithm is applied to improve KNN, which is the KNN/IFCM hybrid algorithm presented in this paper. In the proposed algorithm, through KNN, k RPs are firstly chosen as the data samples of IFCM based on signal to noise ratio(SNR). Then, the k RPs are classified into different clusters through IFCM based on SNR. Experimental results indicate that the proposed KNN/IFCM hybrid algorithm generally outperforms KNN, KNN/FCM, KNN/PFCM algorithm when the locations error is less than 2m.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.2
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• pp.109-115
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• 2011

As fingerprinting method, k-nearest neighbor(KNN) has been widely applied for indoor location in wireless location area networks(WLAN), but its performance is sensitive to number of neighbors k and positions of reference points(RPs). So artificial neural network(ANN) clustering algorithm is applied to improve KNN, which is the KNN/ANN hybrid algorithm presented in this paper. For any pattern matching based algorithm in WLAN environment, the characteristics of signal to noise ratio(SNR) to multiple access points(APs) are utilized to establish database in the training phase, and in the estimation phase, the actual two dimensional coordinates of mobile unit(MU) are estimated based on the comparison between the new recorded SNR and fingerprints stored in database. In the proposed algorithm, through KNN, k RPs are firstly chosen as the data samples of ANN based on SNR. Then, the k RPs are classified into different clusters through ANN based on SNR. Experimental results indicate that the proposed KNN/ANN hybrid algorithm generally outperforms KNN algorithm when the locations error is less than 2m.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.590-592
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• 1997

Making physical models of human body is not only time-consuming but also very expensive since they are usually hand-made. This problem is doubled with implant fabrication because an implant is almost always custom-made. Recently, RP is emerging as an alternative, and many RP applications are proposed in the medical field. The major advantage of this approach is due to a significant reduction of both time and cost required or the production. However, the technology is not much in practical use yet, especially in Korea. In this paper, we provide a method of generating STL files that are the standard format to RP machines. The original data are obtained from two-dimensional slices of MRI/CT machine. Example bone models have been produced using a commercially available RP machine, and the results are presented.

• Korean Institute of Interior Design Journal
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• v.17 no.3
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• pp.102-110
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• 2008

The purpose of this study is to find out the characteristics of color preference(interior color preference and general. color preference) and preferred color scheme of the youth and the elderly. This is to proffer basic data for the color planning of the youth and the elderly. The color preference study was carried out with 50 color chips and preferred color scheme study was carried out with 25 interior color scheme. The research was conducted with the youth 50 sample and the elderly 51 sample. The analysis used spss program. The results of this study are as follows;1) In general color perference, most of the youth preferred PB and GY, and the elderly preferred RP. According to tone, two groups preferred pale, bright and vivid tone. 2) In interior color perference, most of the youth preferred GY and Y, and the elderly preferred PB and YR. According to tone, two groups preferred pale tone. Compared with general color perference and interior color perference, the youth had the similarity in preference profile, but the elderly didn', there was the outstanding difference in the perference of B, PB, P and RP. 3) In the preference of interior scheme, two groups preferred GY-analogous harmony1, G-analogous harmony1 and RP-analogous harmony1. According to age, the youth preferred Y-analogous harmony2 and PB-analogous harmony1, and the elderly preferred YR-analogous harmony1 and RP-complementary harmony1. On the whole, two groups more preferred analogous harmony than complementary harmony, and preferred type1(tone difference is slight). But there was the significant difference in analogous harmony of cool color.