• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.386-389
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• 2003

Recent issues in Optical Disk Drive (ODD) are focused on small size. Blu-ray Disk (BD), using blue laser (405nm wavelength) and high NA (0.85) objective lens. can store 25Gbyte on a conventional 12cm optical disk. Small Form Factor Optical (SFFO) drive uses 3cm disk which can store 1.5Gbyte on a disk. This kind of Small Form Factot Optical (SFFO) drive correspond to PCMCIA type memory (Compact Flash or Micro Drive). Preferably, Optical Disk has relatively low cost of the storage media per Byte rather than PCMCIA type memory. To make Small Form Factor Optical (SFFO) drive. optical pickup and its component must be miniaturized. Miniaturization of the component needs new concept of Optical Pickup. This paper is focused on two main subjects. One is Objective Lens design which can be manufactured on a wafer, and the other is optical path design of the pickup which has 2mm thickness.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.779-783
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• 2008

LRFD Resistance factors for static bearing capacity of driven steel pipe piles were calibrated in the freamework of reliability theory. Reliability analysis was performed by the First Order Reliability Method (FORM) using resistance bias factor statistics.The target reliability indices are selected as 2.0 and 2.33 for group pile case and 2.5 for single pile case, based on the reliability level of the current design practice and considering redundancy of pile group, acceptable risk level, construction quality control, and significance of individual structure.

• Korean Institute of Interior Design Journal
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• no.11
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• pp.31-37
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• 1997

This study intens to provide available guideline of useful plants in interior and be used by designer. It focuses on evaluating the character of plants, the method of installation and the form of composition for suitable design of using plants. The study finds out that using plants in interior are necessary positively by 94% respondents. And results of factor analysis are that plants are needed for emothional stability(factor 1), visual charming(factor 2), and educational effection(factor 3). According to job, the group of students is visual charming (P=0.0037), the public servants and housewives is educational effection(p=0.0029). The most available space of plants as follows : Department(30.5%), Hotell(26.3%), House and Restuarant(12.7%). It has been identified that the public institution and commercial space are much indused plants. The most indused plants in house is ordered that the veranda, the living room, the entrance. This result is concerned about relation of natural light plants. The repondants reply that the favorite arrangement style is the corner form(63%), the center garden form(52.1%), the large planter(19.7%), the planter box(11.3%). They respond that they are more favorite light green color than dark, and mono color than mixture color. Finally, interior Designers should be understood the functional and aesthetic elements and the special interest about plants for developing desigv.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.188-191
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• 2005

Two different coverlayers which is useful for an optical buffer and a mechanical protection made of not only UV resin but also polycarbonate coversheet were prepared on small form factor optical disks. Thin coverlayer of 10 ${\mu}m$ and thick coverlayer of 80 ${\mu}m$ were fabricated. 10 ${\mu}m$-thick coverlayer was coated using UV resin material by spin coating method for the flying optical head application. On the other hand, 80 ${\mu}m$-thick coverlayer using coversheet with the resin bonding material was prepared for the non-flying optical head application. Both cases, the thickness uniformity seem to be the primary prerequisite factor, and it was analyzed. Thickness of 10 ${\mu}m$-thick UV resin coverlayer could be controlled within ${\pm}0.2m$ range and 80 ${\mu}m$-thick coversheet could be controlled within ${\pm}3{\mu}m$ range. However, the yield of such thickness tolerance was not good. New design of metal housing holder and polycarbonate outer ring was adopted to diminish the ski-jump phenomenon. Specifically, the polycarbonate outer ring was very effective to reduce the ski-jump. However, it should be careful to maintain uniform edge between disk and ring for the perfect coverlayer.

• Steel and Composite Structures
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• v.29 no.4
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• pp.483-491
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• 2018

Timoshenko beam model is widely exploited in the literature to examine the mechanical behavior of stubby beam-like components. Timoshenko beam theory is well-known to require the shear correction factor in order to recognize the nonuniform shear distribution at a section. While a variety of shear correction factors are appeared in the literature so far, there is still no consensus on the most appropriate form of the shear correction factor. The Saint-Venant's flexure problem is first revisited in the frame work of the classical theory of elasticity and a highly accurate approximate closed-form solution is presented employing the extended Kantorovich method. The resulted approximate solution for the elasticity field is then employed to introduce two shear correction factors consistent with the Cowper's and energy approaches. The mathematical form of the proposed shear correction factors are then simplified and compared with the results available in the literature over an extended range of Poisson's and aspect ratios. The proposed shear correction factors do not exhibit implausible issue of negative values and do not result in numerical instabilities too. Based on the comprehensive discussion on the shear correction factors, a piecewise definition of shear correction factor is introduced for rectangular cross-sections having excellent agreement with the numerical results in the literature for both shallow and deep cross-sections.

• Communications of Mathematical Education
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• v.29 no.1
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• pp.51-72
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• 2015

This study aimed to analyze the characteristic of undergraduate students' perception and preference for mathematics. For this purpose, I surveyed 124 undergraduate students' metaphorical expressions about mathematics. I classified the expressions as four categories: a positive form, a negative form, a mixed form, an undecidable form. I investigated the proportion and characteristic of the metaphorical expressions according to the above four categories. Also, I surveyed the students' preference and nonpreference moments for mathematics and categorized them into 6-cases: elementary school, middle school, high school, university, always, and none. In addition, I examined the students' preference and nonpreference reasons for mathematics and classified them according to the 5-factors: grade factor, affective factor, content factor, teacher factor, and other factors. The results of this study as follows: First, the 27% of university students expressed their metaphorical expressions for mathematics as a positive form, 42% as a negative form, and 27% as a mixed form. Also, the preference rate for mathematics was higher as their school years increase and the main reasons of preference were grade and affective factors. The result of nonpreference rate was also higher as their school year increased. Students said that the contents and grade factor were the main factors among the 5-factors.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.4
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• pp.11-18
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• 2000

This paper is concerned with the generation of an optimal forward hull form by a nonlinear programming method. A Rankine source panel method based on the inviscid and potential flow approximation is employed to calculate the wave-making resistance and SQP method is also used for the optimization. The hull form is represented by a spline function. The forward hull form of a minimum wave resistance with the given design constraints is generated. In addition, the forward hull form of a minimum total resistance by considering the frictional resistance together with an empirical form factor is produced and compared with the former result.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.4
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• pp.9-18
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• 2002

This study investigated the influential range of landmarks and the relationship between landmarks and cognition factor so as to offer basic data to be used for the effective use and the management of landmarks. In this study, eighteen famous landmark in Seoul were selected and analyzed. The result of this study can be summarized as follows : 1) First, eighteen determining elements of cognition factors were selected via documents survey. Second, general cognition factors of landmarks were analysed using these elements through questionnaires to specialists. As a result of factor analysis, historic cultural factor, scale factor, visual form factor, locational factor and uniqueness factor were revealed. 2) According to revealed cognition factor, eighteen landmarks are categorized into four types using MDS method via questionnaire to resident in Seoul city. These four types of landmarks are: type I that are recognized by historic cultural factor; type II that are recognized by scale factor; type III that are recognized by uniqueness factor; and type IV that are recognized by visual form factor. 3) As the result of regression, the influential range of landmarks were revealed at about a 10km radius(type I : 12km type II : whole area of Seoul city≒15km, typeIII : 8.7km, typeIV : 8.5km). 4) As a result of analysing the correlation between the influential range and the cognition factor through multiple linear regression analysis, the locational factor is the main factor affecting the influential range of landmarks in every type. The uniqueness factor comes next, which affects influential range partially. 5) Except type 1, as a result of analysing the correlation between influential range and the physical heights of landmarks, a quadratic equation is revealed, showing that the influential range of landmarks over 200 meters in height shows a radical change. Landmarks can be used as reinforcement tools of legibility, effective tools for landscape management and for the improvement of a community's image. This study on the influential range of landmarks and main cognition factor can be utilized as a landmark management plan and in urban planning, such as a new town plan.

• Korean Journal of Psychosomatic Medicine
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• v.4 no.1
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• pp.21-36
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• 1996

This study was attempted to investigate reliability and validity of premenstrual assessment form(PAF). PAF was administered to 230 high school students who had reported premenstrual changes. PAF revealed considerable diversity in premenstrual symtom changes of the subjects. The items with most frequent reported premenstrual changes were 21 items out of 95. Cronbach's internal consistency was .95, and test-retest reliability was .80. Validity test was performed by constructional validation analysis. 8 factors(impulsive & unstable factor, depressive factor, withdrawal & social functioning impairment factor, anxiety & cognitive dysfunction factor, physiological factor, general discomfort factor, increased well-being factor, other factor) emerged at factor analysis. Each of them accounted for 33.97, 5.10, 3.70, 2.93, 2.64, 2.46, 2.12, 2.03 of total variance respectively. High school students experienced impulsive & unstable features of premenstrual symptoms more frequently. This study suggests PAF can be a reliable and valid tool as a initial screening and evaluation of premenstrual changes. finally, factor analysis result was compared with PAF typological categories.

• Archives of design research
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• v.16 no.4
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• pp.405-412
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• 2003

This research investigated the preference factor which has an effect on the forms of bus stop shelter in order to grasp the visual preference factor, which is necessary for planning and designing of bus stop shelter centering around user, starting with the question of the research regarding that a shelter is preferred by what kind of factor when the environmental conditions are regular. This research examined the relation between visual preference and preference factor which has an effect on it with Multiple Regression Analysis after evaluating visual preference for shelter form by user as applying of scoring system of Interval Scale. The result of the factor analysis by visual evaluation for the form of bus stop shelter through the said research result will have an great effect on the design of bus stop shelter centering around its user. Therefore, this research result will give a knowledge which is necessary for the plan and the installation of bus stop shelter, and contributes to shelter design and bus stop promotion which can maximize the satisfaction of user. As well, concerning the management of bus stop facilities, it will give useful guidelines for planning strategically the shelter management centering around user. In particular, It is estimated that the preference factor analysis by visual evaluation of the mass transportation user in daily life will be the cardinal point for bus stop plan.