• Management Science and Financial Engineering
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• v.4 no.2
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• pp.43-58
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• 1998

Packet switch is a key component in high speed digital networks. This paper investigates congestion phenomena in the packet switching with input buffers. For large value of switch size N, mathematical models have been developed to analyze asymptotic maximum switch throughput under nonuniform traffic. Simulation study has also been done for small values of finite N. The rapid convergence of the switch performance with finite switch size to asymptotic solutions implies that asymptotic analytical solutions approximate very closely to maximum throughputs for reasonably large but finite N. Numerical examples show that non-uniformity in traffic pattern could result in serious degradation in packet switch performance, while the maximum switch throughput is 0.586 when the traffic load is uniform over the output trunks. Window scheduling policy seems to work only when the traffic is relatively uniformly distributed. As traffic non-uniformity increases, the effect of window size on throughput is getting mediocre.

• Journal of Powder Materials
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• v.7 no.4
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• pp.205-211
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• 2000

Distribution of $Y_2BaCuO_5$ (211) Particles within $YBa_2Cu_3O_{7-x}/$ (123) grains of melt infiltration processed YBCO oxides was investigated. Processing parameters were a temperature, atmosphere (air and $O_2$) and initial 211 size. The 211 particles were distributed randomly within the 123 grains when the initial 211 size was large, while they made x-like pattern and/or butterfly-like patterns when the 211 size was small. The 211 patterns were more clearly observed in the samples prepared at higher temperatures and under $O_2$ atmosphere. The 211 distribution was explained in terms of the interfacial energy relationship among the solid, particle and melt.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.100.2-100.2
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• 2012

Surface texturing of crystalline silicon is carried out in alkaline solutions for anisotropic etching that leads to random pyramids of about $10{\mu}m$ in size. Recently textured pyramids size gradually reduced using new solution. In this paper, we investigated that texture pyramids size had an impact on emitter property and front electrode (Ag) contact. To make small (${\sim}3{\mu}m$) and large (${\sim}10{\mu}m$) pyramids size, texturing times control and one side texturing using a silicon nitride film were carried out. Then formation and quality of POCl3-diffused n+ emitter in furnace compare with small and large pyramids by using SEM images, simulation (SILVACO, Athena module) and emitter saturation current density (J0e). After metallization, Ag contact resistance was measured by transfer length method (TLM) pattern. And surface distributions of Ag crystallites were observed by SEM images. Also, performance of cell which is fabricated by screen-printed solar cells is compared by light I-V.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.3
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• pp.566-574
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• 1988

A study is described for obtaining real time in situ size and velocity measurements of the spray-droplet using crossed-beam interferometry. The optical arrangement is similar to dual-beam laser Doppler velocimetry(LDV). Droplets passing trough the probe volume scatter light to the collecting lens placed at 90.deg. off-axis angle. The dual-beam light scatter is analyzed by the geometric optics theory to relate the scattered fringe pattern to droplet diameter. The droplet size measurement is based upon the signal visibility. As the system is based on the Doppler effect, a single component of velocity is velocity is extracted concurrent with the size information. The validity of the method is evaluated by comparing its performance to widely accepted but limited technique, the collection method. By using 90.deg. off-axis scatter detection angle, the measurement of the droplet size and velocity distributions, and the local correlations between droplet sizes and velocities in relatively dense spray environments are made possible.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2002.05a
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• pp.111-116
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• 2002

The regularity effect for printed word recognition and naming depends on ambiguities between single letters (small grain-size) and their phonemic values. As a given word is repeated and becomes more familiar, letter-aggregate size (grain-size) is predicted to increase, thereby decreasing the ambiguity between spelling pattern and phonological representation and, therefore, decreasing the regularity effect. Lexical decision and naming tasks studied the effect of repetition on the regularity effect for words. The familiarity of a word from was manipulated by presenting low and high frequency words as well as by presenting half the stimuli in mixed upper- and lowercase letters (an unfamiliar form) and half in uniform case. In lexical decision, the regularity effect was initially strong for low frequency words but became null after two presentations; in naming it was also initially strong but was merely reduced (although still substantial) after three repetitions. Mixed case words were recognized and named more slowly and tended to show stronger regularity effects. The results were consistent with the primary hypothesis that familiar word forms are read faster because they are processed at a larger grain-size, which requires fewer operations to achieve lexical selection. Results are discussed in terms of a neurobiological model of word recognition based on brain imaging studies.

• Korean Journal of Community Nutrition
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• v.3 no.5
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• pp.739-747
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• 1998

The purpose of this study was to compare the dietary habit and nutrient intakes of Korean farmers according to their different family patterns and farming types. Food and nutrient intakes were obtained by food frequency method. The subjects(male 35%, female 65% : mean age, $48{\pm}11 years)$ were compared 46% of nuclear family, 59% of 3-4 person of family size ; 50% of middle-scale farming ; 54% of rice farming. Sixteen percent were over 60 years old group. In aspects of dietary habit, farmers of medium size farming and 10-20 years of farming experience frequently skipped meals. But their appetite was better than small farm famers. Dinner irregularity was more frequent in their group of 3-4 person families. The numbers of food intake were significantly different according to family pattern. Nuclear family groups consumed more kinds of foods. The mean energy intake was 2000Kcal/day, with PFC ratio of 19 : 16 : 65. The energy and nutrient intakes showed the same tendency as the food variety. Intakes of calcium and iron were lower than the Korean RDA. Families with over 5 people consumed higher amounts of protein and minerals. Intakes of thiamin, niacin, and vitamin E were better in large families and large-scale farming groups. As compared with the PMS ratio, the level of monounsaturated fatty acids as higher than saturated FA. The lipid intake was also better in large families and large-scale farming. The results suggest that dietary habit and nutrient intakes were different by family pattern and farming types.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.3
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• pp.3878-3884
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• 1975

This study was carried out to develop the throw-in type thresher with its size as small as possible. Developing the smallest possible size of the throw-in type thresher has been very important to increase mobility and to reduce the machine price. The thresher that developed for this purpose was tested as to threshing and separation performance for the samples collected in eight catch boxes under the concave while threshing. The amount of grain collected in each compartments was measured and the threshing and separating pattern along the total span of the threshing drum was determined. The performance of separating and threshing units of the test thresher and threshing loss was evaluated by use of the developed grain separating apparatus and the method for measuring the grain separating performance of threshers. The results are summarized as follows; 1. The unthreshed grain (drum losses) and semi-threshed grain did not appeared at all throughout the treatments. 2. When threshed by making use of the developed throw-in type thresher, the threshing grain loss at about 25 per cent grain moisture was about one-half when threshed at about 18 per cent grain moisture. 3. And its grain separating loss in higher feed rate was decreased in comparison with that of lower feed rate. These results suggests that the throw-in type thresher may be suitable for wet threshing and for higher feed rate of threshing. 4. Above 60 per cent of total grain passing through concave fell through the screen within a scant 30 cm from the feeding inlet. This threshing pattern may suggest that major threshing action may be finished before about one third of cylinder length. The required separating load extended over the whole drum span is so defferent that separating elements should be redesigned so as to accomodate this variable pattern of separation load. 5. It was apparent from the experiment that the length of the threshing drum of the throw-in type thresher could be reduced from 1285mm to about 1050mm without increasing grain separation loss greatly.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.343-345
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• 1998

By computer simulation, the pattern of magnetic field distribution on the Nb-foil of a rotating flux type superconducting power supply has been calculated. Using the results, the current pumping rate has been calculated and compared with the results obtained by the experiment. The experiment has been executed with small-size flux-rump in the environment of LN2 and LHe in order to compare the pattern of magnetic filed in the superconducting state and in the normal state. Five hall-sensor was located on the center, right side, left-side, upper side, lower side of the Nb-foil in order to obtain more accurate pattern of the magnetic field generated by rotating pole. In the simulation, the effects of the excitation-magnet and the iron core located at the inner-side and circumference of the magnet have been considered. By comparing the data from the experiment and the results from the simulation, the size of normal spot estimated. At the same time, by calculating the linkage flux, the current-pumping-rate has been obtained. Consequently, the results obtained from experiment and simulation coincided as expected.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.930-933
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• 2000

In this report experimental ultrasonic machine system has been fabricated and experimental machining has been performed using glass as a workpiece material. As grit size increases, material removal rate(MRR) was observed to be increased at decreased applied tool pressure on the workpiece, however at the higher applied pressure above $2-4\;kg/cm^2$ for smaller grit size, the MRR was not increased. Also better surface roughness was obtained for smaller grit size. Microchipping was observed from the microscopic examination and the pattern is similar to the iso-stress field where cracking is considered to be initiated near the surface.

• Journal of the Korean Home Economics Association
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• v.43 no.10 s.212
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• pp.179-190
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• 2005

The purpose of this study was to apply the three dimensional Replica method to the fabrication of dress forms of plus-sized women to attain proper ease through draping and based on the ease to develop good torso patterns with superior fit. The results were as follows. The physical characteristics of the dress forms of plus-sized women were divided into two: Types I and 11. The proper ease was calculated through draping using dummies of each somatotype and appropriate torso patterns were developed. The differences of the types for each pattern were as follows. The bust girth ease of Type II was 6cm as for Type I. As for the bust breadth 1.0cm was added to the anterior chest width, the armpit width was the actual measurement plus 0.5cm, and the back breadth was the posterior chest width plus 2.5cm. The bust breadth was smaller and the back breadth was bigger that those of Type I after improving the bust and back fit. The bust of Type I protrudes outwards relatively and so the shoulder dart of front-side of Type I was 1.2cm bigger than that of Type II which improved the bust region fit. Considering the characteristics of the protruding abdominal region the front- side waistline of type II was assigned W/4+3.5cm and the back-side waistline W/4cm, so that the sidelines divided the front and back properly. It was drafted so that the center-front became diagonal, thereby improving the middle-hip girth fit.