• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.2
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• pp.104-107
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• 2009

It was verified that the effect of the distance between current input point and output point on direct current potential drop(DCPD) in the material with two-dimensional surface notch. If the distance between potential drop measuring points was fixed at a certain distance, the potential drop was decreased with increasing the distance between current input and output points. Hence it is the effect way to increase sensitivity in DCPD that the current input and output points should be located near the potential measuring points. DCPD was a useful method for surface crack sizing because the potential drop was proportional to the length of notch. When the current input and output points are located near the potential measuring points, even small length crack can be measured by DCPD technique.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.5
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• pp.543-551
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• 2011

The paper deals with the comparative study of design optimization based on various approximation techniques in strength design of riser support structure installed on floating production storage and offloading unit(FPSO) using offshore operation loading conditions. The design optimization problem is formulated such that structural member sizing variables are determined by minimizing the weight of riser support structure subject to the constraints of structural strength in terms of loading conditions. The approximation techniques used in the comparative study are response surface method based sequential approximate optimization(RBSAO), Kriging based sequential approximate optimization(KBSAO), and the enhanced moving least squares method(MLSM) based approximate optimization such as CF(constraint feasible)-MLSM and Post-MLSM. Commercial process integration and design optimization(PIDO) tools are employed for the applications of RBSAO and KBSAO. The enhanced MLSM based approximate optimization techniques are newly developed to ensure the constraint feasibility. In the context of numerical performances such as design solution and computational cost, the solution results from approximate techniques based design optimization are compared to actual non-approximate design optimization.

• Journal of the Korean Solar Energy Society
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• v.32 no.3
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• pp.68-76
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• 2012

Since the solar energy resource is the main input for sizing any solar energy utilization system, it is essential to utilize the solar radiation data as an application and development of solar energy system increase. It will be necessary to understand and evaluate the insolation data. The Korea Institute of Energy Research(KIER) has begun collecting horizontal global insolation data since May, 1982 at 16 different locations in Korea and for the more detailed analysis, images taken by geostationary satellite may be used to estimate solar irradiance fluxes at earth's surface. It is based on the empirical correlation between a satellite derived cloud index and the irradiance at the ground. From the results, the measured data has been collected at 16 different stations and estimated using satellite at 44 different stations over the Korean peninsula from 1982 to 2010. The Result of analysis shows that the annual-average daily global radiation on the horizontal surface is 3.66 $kWh/m^2/day$ and estimated solar radiation fluxes show reliable results for estimating the global radiation with average deviation of -7.2 to +3.7 % from the measured values.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.2 s.120
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• pp.25-30
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• 2007

Recently the use of web offset printing has been increasing, which can provide high print speed, mass production, and high print quality. However, high speed web offset printing has frequently undergone a blistering problem when the printed paper passes through hot air dryers. Blistering occurs in the middle of the base paper or in the coating layer. This paper focused on the blistering occurring in the base paper. In order to elucidate the effect of pigment ratio on blistering, 6 types of coating color were prepared with varying GCC/clay ratios and printability and blistering were investigated focusing on structure changes in the coating layer. When the clay content in the coating layer was increased, surface roughness and surface strength were decreased and paper gloss was increased. In addition, it was found that the coating layer structure with high clay content, which contains lots of discontinuous pores, hindered water vapors to penetrate out and, as a result, blistering occurred.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.5
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• pp.573-581
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• 2002

This study was done to classify children's somatotypes and to provide the fundamental data or their clothing sizing system for the purpose of designing patterns fur children's wear and standardizing sizes of ready-made clothes. The sampling was done for 7-8 years-old-girl living in Pusan and Kyungsangnam-do. Data from each girl comprises 33 anthropometic measurments and 7 photogrphic measurments, based on the somatometric characteristics of girls which I had obtained. Factor analysis, cluster analysis, discriminant analysis were performed for statistical analysis of the data. Seven factors which explain 76.49% of the whole variances were extracted. The thirst and second factors which explain more than 70% of the whole variances represent 'horizontal size 'and 'vortical size', which characterize most aspects of the body shape of the subjects. On the basis of the cluster analysis, three different upper body types were categorized. Type 1 has quite long surface length of the upper body and rising shoulders and are close to the averages of this age group. Type 2 has highest stature, biggest frame, dropped shoulders and surface length of the upper body similar to the type 1. Type 3 has shortest stature, smallest frame and sloping shoulders. According to the analysis to discriminate somatotypes of the upper body by this age group, the discriminative items in discriminant function are follows. As this group, waist circumference of discriminant function 1 and front length and length between both shoulder points of discriminant function 2 have large coefficient values.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.1
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• pp.53-58
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• 2002

New nondestructive inspection (NDI) technique to detect the defect in metal was developed in which an electromagnetic field is induced in a metal by AC current flowing in the magnetic coil and the leak magnetic-flux disturbed by defects is measured using a tape-recorder head with air gap. This technique can be applied in evaluating the location and sizing of surface defects in components of the ferromagnetic body by means of the non-contacting measurement. In this paper, we have applied this technique to the evaluation of two-dimensional surface cracks in ferromagnetic metal, and also investigated the influence of the various frequencies and lift-off. Defects were detected with maximum values in the distribution of voltage and it was found that the maximum values tend to increase with the defect depth. Although the maximum values for defects are affected by the frequency and lift-off, the depth of small defects can be estimated from the linear relationship between the depth and voltage rate$(V_0/V_{ave})$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.56-56
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• 2009

반도체 device가 점점 고집적화, 다층화 되면서 막질의 평탄화를 위한 CMP (chemical mechanical planarization) 공정은 반도체 제작 공정에서 필수 요건이 되었다. 특히 pad conditioning은 CMP 공정 중, 막질의 제거율과 균일도를 유지시키기 위한 중요한 공정이다. 하지만, conditioner를 장시간 사용할 경우 slurry residue와 같은 잔류 오염물질들이 conditioner의 표면의 오염을 유발할 수 있고 이로 인해 conditioner의 수명이 단축되거나 웨이퍼 표면에 결함을 유발할 수도 있다. 본 연구에서는 이를 방지하기 위해 vapor SAM을 이용하여 Ni conditioner 표면에 소수성 박막을 증착하여 오염여부를 평가해 보았다. 먼저, Ni wafer를 이용하여 증착 온도와 압력에 따라 소수성 박막을 증착하여 표면특성을 평가해 보았다. 증착전과 후에 Ni wafer 표면의 접촉각은 contact angle analyzer (Phoenix 400, SEO, Korea)를 이용하여 측정하였다. 박막 표면 형상과 거칠기는 AFM (XE-100, PSIA, Korea)를 이용하여 평가되었고 묘면 성분 분석을 위해 FT-IR (Nicolet 6700, Thermo Scientific, USA)이 사용되었다. SEM (S-4800, Hitach, Japan)은 박막 증착 전과 후의 conditioner를 이용하여 실제 conditioning후 conditioner 표면의 particle 오염정도를 관찰하기 위해 사용되었다. 또한, conditioner 표면에 실제 오염되어있는 particle 개수를 평가하기 위해 particle size analyzer (Accusizer 780A, Particle Sizing Systems Co., USA)을 사용하였다. 본 실험을 통해 최적 증착 조건을 확립하였으며 실제 conditioner 표면에 소수성 박막을 증착 후 $100^{\circ}$ 이상의 높은 contact angle을 확인할 수 있었다. 또한, 소수성 박막이 증착된 conditioner의 경우 실제 conditioning후 표면 particle 오염이 현저히 감소되었음을 확인할 수 있었다.

• International Journal of Costume and Fashion
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• v.5 no.1
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• pp.1-13
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• 2005

Two hundreds of female aged 19 years old and up were recruited to evaluate the postural changes and bilateral variation of asymmetry over age. To find out the differences among the age group, subjects were classified into 5 groups, early young age(19-29), late young age(30-39), early middle age(40-49), late middle age(50-59), and old age(60-). 35 body measurements were taken by the 3-D body scanner which allowed us to take measurements which cannot be measured using traditional methods, including the shape of a cross section, slice area surface are, and volume. Bilateral variations were observed as a function of age; Depth of scapular point level, scapular point to center back, and blade angle. Postural change of anterior cervical angle, upper anterior thoracic angle, upper posterior thoracic angle, posterior cervical angle, and center back/center front ratio were also exhibited. In each measurements, subjects were classified into normal, and abnormal group. Percentiles of abnormal in shoulder line angle, blade angle, neck point $\∼$ acromial point $\∼$ scapular point, posterior cervical angle, and upper posterior thoracic angle were increased over age group. The upper body of lateral view was classified into 3 types of posture based on the previous research; straight, erect(leaning back), and stooped(bent forward). The percentiles of subjects who have straight postures were decreased as a function of age, but those of stooped postures were increased. Subjects who have erect postures did not so. The stooped posture group shows the big cervical fossa angle, anterior cervical angle, posterior cervical angle, upper posterior thoracic angle, and the small upper anterior thoracic angle comparing to the straight and erect posture group. These results could be apply for clothing construction reflecting the changes in back, shoulder, neck, and the bilateral asymmetry according to the target age group.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.2 s.115
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• pp.61-71
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• 2006

Environment-friendly shock-absorbing (cushioning) materials were made using a vacuum forming method from waste wood collected from local mountains in Korea. The waste wood was pulped by thermomechanical pulping. The TMP cushions showed superior shock-absorbing properties with lower elastic moduli compared to EPS(Expanded Polystyrene) and pulp mold. Even though the TMP cushions made using at different suction times had many free voids in their inner fiber structures, their apparent densities were a little higher than EPS and much lower than pulp mold. The addition of cationic starch improved elastic modulus of the TMP cushions without increasing the apparent density, which was different from surface sizing with starch. The porosity of the TMP cushions was a little greater than EPS and much less than pulp mold. Finally, the TMP cushions have great potential to endure external impacts occurring during goods distribution.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.4
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• pp.85-90
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• 2011

With regard to reliability of solder joint, the significant failures include open defects that occurs from alignment problem, Head in Pillow by PCB's warpage, the crack of solder by CTE mismatch, and the crack of IMC layer by mechanical impact. Especially as PCB down-sizing and surface finish is under progress, brittle failure of IMC layer between solder bump and PCB pad becomes a big issue. Therefore, it requires enhancing the level of difficulty in the existing assessment method and improving the measurement through the study on the mechanism of IMC formation, growth and brittle failure. Under this circumstance, this study is intended to suggest the direction of research for improving the reliability on the crack such as improvement of IMC brittle fracture.