• Korean Journal of Optics and Photonics
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• v.20 no.3
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• pp.175-181
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• 2009

Holographic lithography is one of the potential technologies for next generation lithography which can print large areas (6") as well as very fine patterns ($0.35{\mu}m$). Usually, photolithography has been developed with two target purposes. One was for LCD applications which require large areas (over 6") and micro pattern (over $1.5{\mu}m$) exposure. The other was for semiconductor applications which require small areas (1.5") and nano pattern (under $0.2{\mu}m$) exposure. However, holographic lithography can print fine patterns from $0.35{\mu}m$ to $1.5{\mu}m$ keeping the exposure area inside 6". This is one of the great advantages in order to realize high speed fine pattern photolithography. How? It is because holographic lithography is taking holographic optics instead of projection optics. A hologram mask is the key component of holographic optics, which can perform the same function as projection optics. In this paper, Surface-Relief TIR Hologram Mask technology is introduced, and enables more robust hologram masks than those previously reported that were formed in photopolymer recording materials. We describe the important parameters in the fabrication process and their optimization, and we evaluate the patterns printed from the surface-relief TIR hologram masks.

• Journal of the Korean earth science society
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• v.41 no.2
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• pp.111-128
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• 2020

This study presents a possibility of intensification of fine dust mass concentration due to the complex urban structure using data mining technique and clustering analysis. The data mining technique showed no significant correlation between fine dust concentration and regional-use public urban data over Seoul. However, clustering analysis based on nationwide-use public data showed that building heights (floors) have a strong correlation particularly with PM₁₀. The modeling analyses using the single canopy model and the micro-atmospheric modeling program (ENVI-Met. 4) conducted that the controlled atmospheric convection in urban area leaded to the congested flow pattern depending on the building along the distribution and height. The complex structure of urban building controls convective activity resulted in stagnation condition and fine dust increase near the surface. Consequently, the residual effect through the changes in the thermal environment caused by the shape and structure of the urban buildings must be considered in the fine dust distribution. It is notable that the atmospheric congestion may be misidentified as an important implications for providing information about the residual probability of fine dust mass concentration in the complex urban area.

• Journal of the Korean Vacuum Society
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• v.18 no.2
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• pp.85-91
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• 2009

There has been a rapid progress for flexible polymer-based MEMS(Microelectromechanical Systems) technology. Polycarbonate (PC) and Poly Methyl Methacrylate (PMMA), so-called acrylic, have many advantages for optical, non-toxic and micro-device application. We studied dry etching of PC and PMMA as a function of % gas ratio in the $O_2/SF_6/CH_4$ temary plasma. A photoresist pattern was defined on the polymer samples with a mask using a conventional lithography. Plasma etching was done at 100 W RIE chuck power and 10 sccm total gas flow rate. The etch rates of PMMA were typically 2 times higher than those of PC in the whole experimental range. The result would be related to higher melting point of PC compared to that of PMMA. The highest etch rates of PMMA and PC were found in the $O_2/SF_6$ discharges among $O_2/SF_6$, $O_2/CH_4$ and $SF_6/CH_4$ and $O_2/SF_6/CH_4$ plasma composition (PC: ${\sim}350\;nm/min$ at 5 sccm $O_2/5$ sccm $SF_6$, PMMA: ${\sim}570\;nm/min$ at 2.5 sccm $O_2/7.5$ sccm $SF_6$). PC has smoother surface morphology than PMMA after etching in the $O_2/SF_6/CH_4$ discharges. The surface roughness of PC was in the range of 1.9$\sim$3.88 nm. However, that of PMMA was 17.3$\sim$26.1 nm.

• Korea journal of population studies
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• v.30 no.3
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• pp.33-56
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• 2007

This study explores the pattern of socio-demographic characteristics of divorced couples of international marriage in Korea. This paper focuses on analyzing the effect of dissimilarity between husband and wife on the duration of marriage of divorced couples. It examines whether the differences of socioeconomic characteristics of the married couples are linked to different process within their relationships and duration of marriage. Attention is focused on couple's age and education. Micro-data from divorce registration for the period of 1995-2005 are utilized. Results of analyses reveal the following. First, married couples may have different responses to dissimilarity between the partners according to the combination of nationality of the couples. This indicates that cross-border marriage does not represent the same type of union in different societies or cultures. Second, both dissimilarities of age and education show negative impacts on the marital duration of the couples with foreign wives, but there is a difference in its pattern. Age dissimilarity displays higher impacts on the duration. Third, the result also indicates that the contribution of dissimilarity of age and education on marital duration is relatively small among the couples with foreign husbands.

• Korea journal of population studies
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• v.29 no.1
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• pp.25-56
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• 2006

This study attempts to review the increasing trend in international marriage of Koreans since 1990 and explore the pattern of socio-demographic characteristics of the married couples. This paper develops a conceptual scheme for changing pattern of nuptiality including an increase in international marriage. As the key forces behind the recent increase in international marriage of Koreans, the effects of rapid decline in fertility, rise in sex ratio at birth, urbanward migration of young women, expansion of gender-equity norms, and globalization are stressed. Micro-data from the marriage registration for the period $1990{\sim}2004$ and the divorce registration for the period $2000{\sim}2004$ are utilized. This study focuses on analyzing age at marriage, previous marital experience, education, occupation, and residence of the married couples. Attention is also focused on demographic characteristics of the divorced couples. Results of analyses reveal that there exists a great deal of diversity in international marriage of Koreans. A notable aspect is the profound differences between Korean men and women in the characteristics of their foreign spouses and themselves as well. Another prominent factor emphasized in the analysis is the nationality of foreign spouse. It is indicated that the stereotype of international marriage facilitated by marriage squeeze can be mainly applied to marriages between Korean men and foreign wives from China, southeast Asian countries and the CIS of the old Soviet Union. On the other hand, direct effects of value transformation and globalization are emphasized in the explanation of marriages between Korean men and foreign wives from more developed countries as well as marriages between Korean women and foreign husbands.

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.149-154
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• 2007

Nanoimprint lithography (NIL) is useful technique because of its low cost and high throughput capability for the fabrication of sub-micrometer patterns which has potential applications in micro-optics, magnetic memory devices, bio sensors, and photonic crystals. Usually, a chemical surface treatment of the stamp is needed to ensure a clean release after imprinting and to protect the expensive original master against contamination. Meanwhile, adhesion promoter between resin and substrate is also important in the nanoscale pattern. In this work, we have investigated the effect of surface treatment using silane coupling agent as release layer and adhesion promoter for UV-Nanoimprint lithography. Uniform SAM (self-assembled monolayer) could be fabricated by vapor deposition method. Vapor phase process eliminates the use of organic solvents and greatly simplifies the handling of the sample. It was also proven that 3-acryloxypropyl methyl dichlorosilane (APMDS) could strongly improve the adhesion force between resin and substrate compared with common planarization layer such as DUV-30J or oxygen plasma treatment.

• Korea journal of population studies
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• v.34 no.1
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• pp.159-178
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• 2011

Korea has been widely recognized as the most successful country for reversal of the rise in sex ratio at birth (from the mid-1980s to the mid-1990s) in a short period of time. However, unusually high sex ratios at birth are still observed in most regions as parity increases. Given that imbalanced sex ratios at high birth orders are mostly due to son-selective abortion, it still remains questionable whether son-selective reproductive behavior has vanished in Korea. The main purpose of this study is to analyze the pattern of changing trends and socioeconomic differentials in sex ratio at birth. Micro-data from birth registration for 2009 are utilized. Attention is focused on analyzing sex ratios at birth in Youngnam region according to age of mother, parity, educational attainment of parents, and occupation of parents. A series of simulations are also conducted in this paper to show how prenatal sex screening and son-selective abortion have affected the level of sex ratio at birth for years 1994, 2005 and 2009.

• Journal of Adhesion and Interface
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• v.25 no.1
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• pp.169-274
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• 2024

Recent attention has been drawn to materials that undergo reversible expansion and contraction in response to external stimuli, leading to morphological changes. These materials hold potential applications in various fields including soft robotics, sensors, and artificial muscles. In this study, a novel material capable of responding to high temperatures for protection or encapsulation is proposed. To achieve this, liquid crystal elastomer (LCE) with nematic-isotropic transition properties and polyimide (PI) with high mechanical strength and thermal stability were utilized. To utilize a solution process, a dope solution was synthesized and introduced into micro-printing techniques to develop a two-dimensional pattern of LCE/PI bilayer structures with sub-millimeter widths. The honeycomb-patterned LCE/PI bilayer mesh combined the mechanical strength of PI with the high-temperature contraction behavior of LCE, and selective printing of LCE facilitated deformation in desired directions at high temperatures. Consequently, the functionality of selectively and reversibly encapsulating specific high-temperature materials was achieved. This study suggests potential applications in various actuator fields where functionalities can be implemented across different temperature ranges without the need for electrical energy input, contingent upon molecular changes in LCE.