• Journal of The Geomorphological Association of Korea
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• v.27 no.3
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• pp.53-73
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• 2020

Morphology and grain size distribution of coastal dunes should be well documented because they are critical to dune's buffering capacity and resilience against storm surges. The nationwide coastal dune survey produced the dataset, including beach-dune topographic profiles and grain size parameters for frontal beaches, foredunes, and inland dunes. This research investigated the dataset to describe geomorphic and textural properties of coastal dunes: foredune slopes, dune heights above approximately highest high water, mean size, and sorting, together with associated variables of coastal setting that influence coastal dunes. It also explores the possibility of a dune type scheme based on gran size trends. The results are as follows. First, the coast in which dunes are developed is the primary control on foredune morphology and sediment texture. Coastal dunes on the east coast were developed more alongshore rather than inland, with gentler slopes on the higher ground and out of coarser sand. The shore aspect contributes to this pattern because the east coast cannot benefit from prevailing northwesterly. Second, grain size trends from beaches through foredunes to inland dunes were little identified. Third, 12 dune types were identified from 69 dunes, showing the indicative capability for the status of beaches and dunes. We confirmed that the dataset could increase our understanding of the overall characteristics of coastal dune morphology and texture, though there is something to be improved, for example, establishing the refined and comprehensive field survey protocol.

• Korean Journal of Human Ecology
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• v.7 no.1
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• pp.147-165
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• 1998

The object of this study was to help designing of well-fit and comfortable brassieres for the elementary school girls through the survey on actual condition of wearing brassieres. The subjects of investigation for this study was the elementary school girls in the province of Jeonbuk and Taejeon city. The conclusion of this study was as follows; The 40.2% of the total subjects were wearing brassieres like the 63.3% of the fourth, the 85.4% of the fifth, and the 89.7% of the sixth grade students. The main reason of non wearing brassieres was for the underdeveloped breast, and also that of wearing brassieres was for the good shape of the breast. The main types of brassieres were ranked "Tank Top type", "Mold type", and "Adolescent girl-Bra". They had started to wear brassieres by the recommendation of adults who were their mother or teachers, and usually wearing brassieres all day. They usually purchased brassieres "with mother together" or "only by their mother". The standard of choosing brassieres was also ranked by FASHION, CONVENIENCE, SIZE, TOUCH, and SWEAT ABSORPTION. The total score of satisfaction for wearing brassieres was showed "Average score" and the score higher in Jeonju and Taejeon than in Kunsan. The higher grade and fatter was showed decreasing the score of satisfaction. The higher grade became, the more various for the size and preferable a pure cotton fabric for brassieres. The favorite types of brassieres were "Sport Bra" and "Volume-up Bra". They usually purchased a little larger size than their original size of that.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.7
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• pp.1013-1020
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• 1997

Among various gyroscopes, the vibrating gyroscope has advantages such as compact size, mass-productivity and low cost. However this kind of gyroscope usually suffer from low linearity and low signal to noise ratio. Therefore, it is necessary to study on vibrating gyroscope to improve performance. In this paper, triangular cross section si selected in consideration for several points. The existing designs of exciting and sensing have some problems such that small signal size and low linearity. This paper proposes new design of exciting and sensing which is named one period exciting and the other period sensing. This design improves signal size, but it cannot improve linearity. This is because above two designs are the same open-loop type. So, another new design is proposed, which is named rebalancing, is applied to one period exciting and the other period sensing. This design are closed-loop type. It feedbacks the output signal. According to control theory, it can improve linearity. The circuits of each design are realized and used to calibration test. Calibration results show that new design of rebalancing improves linearity and signal size.

• Journal of the Korean Ceramic Society
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• v.45 no.9
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• pp.507-511
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• 2008

A "C-sphere" specimen geometry was used to determine the failure strength distributions of a commercially-available bearing-grade silicon nitride ($Si_3N_4$) with ball diameters of 12.7 and 25.4 mm. Strengths for both diameters were determined using the combination of failure load, C-sphere geometry, and finite element analysis and fitted using two-parameter Weibull distributions. Effective areas of both diameters were estimated as a function of Weibull modulus and used to explore whether the strength distributions predictably scaled between each size. They did not. That statistical observation suggested that the same flaw type did not limit the strength of both ball diameters indicating a lack of material homogeneity between the two sizes. Optical fractography confirmed that. It showed there were two distinct strength-limiting flaw types common to both ball diameters, that one flaw type was always associated with lower strength specimens, and that a significantly higher fraction of the 25.4-mm-diameter C-sphere specimens failed from it. Predictable strength-size-scaling would therefore not result as a consequence of this because these flaw types were not homogenously distributed and sampled in both C-sphere geometries.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.2
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• pp.126-137
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• 2007

In this paper, a new method to reduce the size of ROM in the direct digital frequency synthesizer(DDFS) is proposed. And we design the phase-to-sine converter using the phase accumulator of parallel type for generating the high frequency. The new ROM compression method can reduce the ROM size by using the two ROM. The quantized value of sine is saved by the quantized-ROM(Q-ROM) and the differential ROM(D-ROM). So the total size of the ROM in the proposed DDFS is significantly reduced compared to the original ROM. The ROM compression ratio of 67.5% is achieved by this method. Also, the power consumption is decreased according to the ROM size reduction.

• International Journal of Korean Welding Society
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• v.3 no.1
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• pp.29-33
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• 2003

The ferritic stainless steels are generally considered to have poor weldability compared with that of the austenitic stainless steels. However the primary advantages of ferritic stainless steels include lower material cost than the more commonly used austenitic stainless steels and a greater resistance to stress corrosion cracking. Thus, the weldability of ferritic stainless steels was investigated in this study. In concerning the weldability, Grain size measurement test, Erichsen test and Varestraint test were involved. full penetration welds were produced by autogeneous direct current straight polarity (DCSP) and pulsed currents gas tungsten arc welding (GIAW) and the effect of pulsed currents welding on the welds was compared to that of DCSP welding. The results showed that pulsed current was effective to refine grain size in the weld metal and the finest grain size was obtained at the frequency of 150Hz. In addition, the ductility of welds was lower than that of base metal. Finally, autogeneous type 444 welds were less susceptible to macro solidification cracks, but more sensitive to micro cracks; SEM/EDS analysis indicated that all the inclusions in the crack showed enrichment of Mn, Si, O and S.

• Journal of the Korean Society of Clothing and Textiles
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• v.18 no.5
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• pp.637-645
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• 1994

The purpose of this study was to analyze the characteristics of men's foot and the foot type by cluster analysis for men's footwear. The sample size for the study was 200 college men between age 19 and 24 in Pusan urban area. There were measured 17 items of the foot for factor analysis and cluster analysis. The result was as follows: 1. The size of If items of men's foot is larger than women's foot. 2. There were 9 items selected by factor analysis. 3. The cluster analysis of the direct measurement: Cluster 1: The items of the direct measurement is all much the same to mean value of this age group. Cluster 2: The foot size is relatively small to other clusters. Cluster 3: The foot size is relatively large to other clusters. 4. The cluster analysis of indirect measurement: Cluster 1: The foot print angle is the most value and Metatarso-Phalanx angle is nomral Cluster 2: The foot print angle is middle and Metatarso-Phalanx angle is normal. Cluster 3: The foot print angle is high and Metatarso-Phalanx angle is the smallest. Cluster 4: The foot print angle is low and Metatarso-Phalanx angle is all the much same to mean value of this age group.

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.732-742
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• 2002

This paper presents twin spray characteristics of two impinging F-O-O-F type injectors in which fuel and oxidizer impinge on each other to atomize under the various conditions. The droplet size and velocity in the impinging spray flow field were measured using PDPA. The droplet size and velocity were investigated at the mixture ratios of 1.5, 2.0, 2.47 and 3.0 for four injectors in which two single F-O-O-F injectors were arranged at the intervals of 20.8, 31.2, 41.6 and 62.4mm respectively. In general, the arithmetic mean diameter, SMD and standard deviation of droplet size in the interaction area (X=0 and Y=0mm) were smaller, while the axial velocity in the interaction area was slightly higher. An empirical correlation is obtained for the (D$\_$10/)$\_$D//(D$\_$10/)$\_$c/ value under the assumptions of two identical droplets and these with different size and velocity. The droplets with low Weber numbers below 40 have possibility to coalesce, while those over 40 tend to disintegrate after impingement in the interaction area.

• Journal of computational fluids engineering
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• v.19 no.1
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• pp.21-26
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• 2014

Butterfly valve is a valve that controls fluid flow depending on the size of the opening angle. In general, the size of the opening angle of the valve increases, the fluid flow has also increased sharply. However, sometimes, in a specific piping system, a particular operating condition is needed that the fluctuation of the fluid flow should not have large amount although the size of opening angle of the valve become larger. In butterfly value, the shape of a typical thin plate, it is impossible to control a minute fluid, but in thick plate type, it is possible. In this study, we got the fluid flow control characteristics and pressure drop through both a numerical method and an experimental method about thick plate type. The numerical result and experimental result of flow coefficient show a similar pattern. In addition, we could find that minute fluid flow control was possible in the area of small size of the opening angle.

• The Journal of Information Systems
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• v.17 no.4
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• pp.181-206
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• 2008

This study aims to investigate the impacts of managerial and technical IT knowledges on firm's financial performance. Specifically, the study examines the following three effects between IT personnel knowledges and financial performance: (1) direct effect, (2) mediating effect of business process performance, and (3) moderating effect of firm size, between them. An empirical study resulted in the followings. First, both managerial and technical IT knowledges do not have direct influences on financial performance. Second, unlike technical IT knowledge, managerial IT knowledge indirectly affects financial performance through business process performance, confirming the mediating role of business process performance. Third, while technical IT knowledge produce no direct and indirect effect on financial performance regardless of firm size, managerial IT knowledge exerts significant impacts on financial performance although such effects represent some different patterns according to firm size. That is, in the smaller group, the association between managerial IT knowledge and financial performance is partially mediated by business process performance and in the larger group, that relationship fully mediated.