• Journal of Adhesion and Interface
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• v.10 no.2
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• pp.98-105
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• 2009

Poly(amic acid) was synthesized from the reaction of p-PDA/ODA and PMDA/BPDA and silane oligomer containing epoxy group was also synthesized from the reaction of tetramethylorthosilicate (TMOS) and glycidol. After hybridizing poly (amic acid) and silane oligomer, they were effectively converted into polyimide/silica hybrid films by thermal imidization process. As the silica contents in hybrid films increased, CTE values decreased from 17 ppm/K to 10 ppm/K and the tensile modulus increased, in spite of decreasing tensile strength. In addition, the peel test showed that the adhesion strength of hybrid film was enhanced from $0.43kg_f/cm$ to $1.02kg_f/cm$. Therefore, it could be concluded that the polyimide/silica hybrid film is effective to enhance adhesion strength for FCCL films.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.399.2-399.2
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• 2016

Cu(In,Ga)Se2 (CIGS) 박막 태양전지는 높은 효율과 낮은 제조비용, 높은 신뢰성으로 인해 박막 태양전지 중 가장 각광받고 있다. 특히 유리기판 대신 가볍고 유연한 철강소재나 플라스틱 소재를 이용하여 발전분야 외에 건물일체형, 수송용, 휴대용등 다양한 분야에 적용이 가능하다. 이러한 유연 기판을 이용한 CIGS 태양전지의 개발을 위해서는 기판의 특성에 따른 다양한 공정개발이 선행되어야 한다. Poly-imide와 같은 유연기판은 공정온도가 $400^{\circ}C$이하로 낮고 기판이 매우 얇아 기존 Mo 공정을 개선하여야한다. 이러한 유연기판의 특성을 고려하여 본 연구에서는 기존 bi-layer Mo의 bottom layer의 두께를 조절하여 박막의 strain을 조절하였다. 유연기판으로는 SKC KOLON에서 제조된 GL type의 기판을 사용하였다. 기판의 두께는 50um이다. 먼저 Mo의 bottom layer 두께 비율을 기존 12.5%에서 50%로 증가 시켰으며 전체 박막의 두께 역시 900nm에서 500nm로 두께를 감소시키며 실험을 실시하였다. 그 후 흡수층은 Co-Evaporation 방법을 이용하여 제조하였으며 이때 공정온도는 기존 공정온도에서 450, $400^{\circ}C$로 낮추어 흡수층을 제조하였다. 소자 제조 후 초기 Mo의 strain 개선과 저온공정이 적용되지 않은 경우 4.4%에서 공정 최적화 후 13%로 효율이 증가하였다. 제조된 흡수층은 SEM, XRF, XRD등을 이용하여 분석하였으며 그 외 일반적인 방법을 이용하여 Mo, CdS, TCO, Al grid를 제조하였다. AR 코팅은 제외 하였으며 제조된 소자는 솔라 시뮬레이터를 이용하여 효율 특성 분석을 실시하였으며 Q.E. 분석을 실시하였다.

• Polymer(Korea)
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• v.34 no.6
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• pp.579-587
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• 2010

To investigate the properties of PET films, PET films were extruded at various temperature above $T_m$ and quenched at $18^{\circ}C$ for amorphous sheet, and stretched along a direction defined as the machine direction (MD) with a transverse direction (TD) above $T_g$ at various stretching ratios and then annealed at various temperatures produced by SKC PET line. Thermal shrinkage of MD and TD increased with decreasing annealing temperature and extruding temperature, and increasing stretching ratio. The degree of crystallinity, density, heat of fusion (${\Delta}H$) and pre-melting point ($T_m'$) increased with increasing annealing temperature and extruding temperature. Number average molecular weight ($M_n$) and intrinsic viscosity decreased with increasing extruding temperature. Tensile strength and modulus increased with increasing stretching ratio, however decreased with increasing annealing temperature. Reflective index of both stretching and thickness direction increased with increasing stretching ratio and annealing temperature.

• Nutrition Research and Practice
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• v.14 no.2
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• pp.134-142
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• 2020

BACKGROUND/OBJECTIVES: North Korean refugees (NKRs) in South Korea are a unique population as they must adapt in a new country with similar cultural traits but different social, political, and economic systems, but little research has been conducted on diet and nutrition in this population. This study examined food security, dietary behaviors, and nutrient intakes among adult NKRs living in South Korea and compared them to those of South Koreans. SUBJECTS/METHODS: The subjects were 139 adult NKRs (25 men, 114 women) living in the Seoul metropolitan area, and 417 age- and sex- matched South Korean controls (SKCs; 75 men, 342 women) selected from the Korea National Health and Nutrition Examination Survey (KNHANES). Food security and dietary behaviors (meal skipping, eating-out, meals with family, nutrition education and counseling, and nutrition label knowledge and utilization) were obtained using self-administered questionnaires. Nutrient intakes were assessed by 24-hr recall. The statistical analysis was performed using IBM SPSS ver. 23.0. RESULTS: In South Korea, food security had improved over the previous 12 months, but remained significantly poorer for NKR women than SKC women. Meal skipping was three times more frequent than for SKCs and eating-out was rare. Average energy intake was 1,509 kcal for NKR men and 1,344 kcal for NKR women, which was lower than those of SKCs (2,412 kcal and 1,789 kcal, respectively). Significantly more NKRs (men 24.0%, women 21.9%) showed simultaneously deficient intake in energy, calcium, iron, vitamin A, and riboflavin than SKCs (men 2.7% (P = 0.003), women 7.0% (P < 0.001)). NKR women had a significantly higher index of nutrient quality (INQ) for some nutrients than SK women. CONCLUSIONS: This study reports significant differences in food security, dietary behaviors, and nutrient intakes between NKRs and SKCs. Generally, NKRs reported lower intakes despite improved food security, but relatively good INQs across nutrients. Further research is needed to understand processes of food choice and consumption among NKRs to provide appropriate support aimed at improving diets.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.659-663
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• 2016

The efficiency of a heterogeneous ruthenium zirconia catalyst ($Ru(OH)_x/ZrO_2$) was demonstrated to the selective oxidative transformation of alkenes or alkynes. The scissions of C-C double bonds to aldehydes and triple bonds to diketones or carboxylic acids were carried out with (diacetoxyiodo)benzene as an oxidant under dichloromethane (5 mL)/water (0.5 mL) solvent system at $30^{\circ}C$ for wide range of substrates. The $Ru(OH)_x/ZrO_2$composite showed higher catalytic activity and selectivity than other ruthenium-based homogeneous or heterogeneous catalysts for the scission reaction. The catalyst exhibited a high mechanical stability, and no leaching of the metal was observed during the reaction. These features ensured the reusability of the catalyst for several times for the oxidative cleavage of unsaturated hydrocarbons.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10B
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• pp.865-875
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• 2008

In this paper, we propose a reliable multicast scheme for the tactical wireless ad hoc network where the members share the situation and operation data. Our scheme consists of two phases to guarantee the reliability. During the dissemination phase, we utilizes an epidemic approach similar to gossip-based ad hoc routing. Then the group members interchange the message reception state information periodically so that they are able to recover missing packets from the other members. We evaluate the performance of our scheme through extensive simulations using the network simulator in comparison with other existing reliable multicast schemes in mobile ad hoc network. Our scheme shows higher packet delivery ratio regardless of the mobility and imposes much lower control overhead to the non-group members compared with the existing schemes.

• Polymer(Korea)
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• v.37 no.2
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• pp.249-253
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• 2013

From poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC) synthesized using $CO_2$, a PLA/PPC/PLA layered film is prepared by coextrusion and then stretched to uniaxial orientation. The mechanical, optical, and barrier properties and shrinkage of the prepared film were investigated in detail. The maximum shrinkage of PLA/PPC/PLA film reached to 60% at $75^{\circ}C$. With increasing PPC content, the ratio of shrinkage of the film was increased and its shrinkagerate was increased. The ratio of shrinkage of the film decreased with increasing stretching temperature. The prepared film has oxygen and vapor transmission barrier properties. In this study, the PLA/PPC/PLA film is expected to be commercialized as a environmentally friendly shrinkable film.

• Journal of Environmental Science International
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• v.11 no.3
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• pp.169-176
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• 2002

The purpose of this study is designed to estimate the air quality of subway stations that have the underground platforms in Pusan Metropolitan City, from September to November 2000, over seven times. The subjects include Yonsan-dong station, Somyon station, Pusan station, Nampo-dong station, and Tushil station. The samplings were conducted at three points of each station, i.e. gate, ticket gates, and platforms. The major materials for analysis were CO, NO, NO$_2$, and $O_3$. The experiment was conducted at 7:00 pm with KIMOTO HS-seven Handy sampler and Tedlar Bag of SKC INC(U.S.A). In order to more fully understand station environments, we also measured temperature at each point. The results showed that $O_3$ average concentration at Yonsan-dong station was higher than others with 38~51 ppb. The average concentration of NO was high at ticket gate and platform at Somyon station(119 ppb, 122 ppb), Nampo-dong station(102 ppb, 100 ppb). These results show that the air pollution of stations with underground shopping malls was higher than others. At Somyon station having a junction station, NO and NO$_2$ concentration level of platform-2(noncrowded) was higher than platform-1(crowded). This is most likely due to the accumulation of air pollutants and inadequate ventilation systems.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.3
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• pp.214-221
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• 2020

Salinity is one of the major abiotic stressors that inhibits the growth, yield, and productivity of crop plants. Therefore, it is necessary to develop crops with increased salt tolerance for cultivation in saline soils such as is found in reclaimed land. The objective of this study was to develop a salt-tolerant silage rice line that grows on reclaimed land. In order to develop this salt-tolerant silage rice, we transferred Saltol, a major QTL associated with salt tolerance, from IR64-Saltol, a salt-tolerant indica variety, into Mogyang, a susceptible elite japonica variety. To determine the effect of salt stress, Mogyang and IR64-Saltol cultivars were grown on a medium containing various concentrations of NaCl in in vitro conditions. Shoot length was found to decrease with increasing salt concentrations, and root growth was almost arrested at NaCl concentrations over 50 mM in the Mogyang cultivar. Based on these preliminary results, we screened five salt-tolerant lines showing superior growth under salt stress conditions. Polymerase chain reaction and sequencing results showed that the introgression types of Saltol QTL were derived from the IR64-Saltol cultivar in almost all selected lines. Based on the observed growth and physiological characteristics, the new Saltol introgression lines showed higher salt tolerance compared to the Mogyang parental cultivar. The salt-tolerant lines identified in this study could be used as a genetic resource to improve rice salt tolerance.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.6 no.1
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• pp.17-27
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• 1996

This study was designed to survey exposure levels of formaldehyde among workplaces in some plywood industries and to compare three sampling methods including the impinger method(IM, NIOSH method No. 3500), the solid sorbent tube method(SS, NIOSH method No. 2541), and the passive bubbler monitor method(PB, SKC). The survey was conducted in seven particle board manufacturing factories, two resin manufacturing factories and two plywood manufacturing factories in Incheon area during the period from March 6 to April 20, 1995. The workplaces included were the hot/cold press, the roller/spreader, the soaking/drying, and the reaction/mixing areas. The results were as follows; 1. The average(GM, GSD) concentrations of formaldehyde by sampling methods were 0.11(4.43) ppm by IM, 0.27(2.03) ppm by SS, and 0.29(2.04) ppm by PB, respectively. The concentrations by 1M method were statistically very significantly lower than those of SS and PB methods, particularly at low air borne concentrations of formaldehyde (p<0.001). 2. The area average concentrations of formaldehyde by workplaces measured with PB bubblers were 0.23(2.08) ppm from the press, 0.23(1.77) ppm from the spreader, 0.24(1.51) ppm from the soaking, and 0.46(1.96) ppm from the reaction areas, respectively. The personal average concentrations of formaldehyde by workplaces measured with PB bubblers were 0.30(1.77) ppm from the press, 0.33(1.54) ppm from the spreader, 0.36(1.46) ppm from the soaking, and 0.84(1.19) ppm from the reaction areas, respectively. 3. No statistically significant differences of formaldehyde concentrations among workplaces except the reaction area(p<0.001) were found. 4. Formaldehyde concentrations from personal samples were higher than those of from area sam pies in all workplaces studied. But no statistically significant differences of formaldehyde concentrations both area and personal samples were found. In conclusion, this study found that although formaldehyde concentrations in some plywood industries in Incheon area were below the regulatory limit of 1 ppm, they were over the limits recommended by NIOSH and ACGIH. This study also suggests that the impinger method may underestimate true formaldehyde concentrations. It implies that there will be more workplaces not meeting current regulatory limit if either the solid sorbent or passive bubbler methods were used instead of the impinger method. It is suggested that passive monitors will be a reasonable alternative for area and personal sampling of formaldehyde if the accuracy and validity of passive monitors be verified before use.