본 연구의 목적은 어머니의 주중 미디어 놀이 횟수가 유아의 놀이상호작용에 미치는 영향에서 자기통제와 주의집중문제의 매개역할을 살펴보는 것이다. 이를 위해 육아정책연구소의 한국아동패널 7차년도 데이터를 사용했고, 자료는 R 4.1.3과 PROCESS macro v4.1 for R로 분석했다. 본 연구의 결과는 다음과 같다. 첫째, 어 머니의 주중 미디어 놀이 횟수는 유아의 자기통제에 부적 영향, 주의집중문제에 정적 영향을 미쳤다. 또래 놀이상호작용에 대해 자기통제는 정적 영향, 주의집중문제는 부적 영향을 미쳤다. 자기통제는 주의집중문제 에 부적 영향을 미쳤다. 둘째, 어머니의 주중 미디어 놀이 횟수가 유아의 또래놀이상호작용에 미치는 영향 에서 자기통제와 주의집중문제는 각각 부적 매개효과가 나타났다. 마지막으로 어머니의 주중 미디어 놀이 횟수가 유아의 또래놀이상호작용에 미치는 영향에서 자기통제와 주의집중문제는 부적 직렬다중매개효과가 있었다. 본 연구의 결과는 유아의 자기통제와 주의집중문제가 어머니의 주중 미디어 놀이 횟수와 또래놀이 상호작용을 매개하는 주요한 요인임을 시사한다.

In this study, the homogeneity and stability of standard samples for proficiency testing in indoor air quality within the country (formaldehyde, benzene, toluene, ethylbenzene, p-xylene, styrene, TVOC) were evaluated. The procedures and statistical analysis methods applied in ISO/IEC 13528 (2009) and KS A ISO Guide 35 (2005) were applied as evaluation methods. The homogeneity evaluation was a statistical analysis of repeated measurements of each of the 11 ports and between the 11 ports concentration data. As a result, the coefficient of variation (CV) was within the range of 1.9%~5.9%. The difference between the ports was found to be insignificant and met the statistical standard specified in KS Q ISO 13528. The stability evaluation was assessed by the change in concentration over the long-term stability of the standard samples stored for 90 days. The coefficient of variation (CV), which was within the range of 2.6%~9.0%, exhibited changes in the concentration of the long-term stored standard samples. However, the results satisfy the statistical standard specified in KS A ISO Guide 35. Overall, there is no significant difference between the homogeneity of the standard samples by the port and the stability of the long-term stored samples. Therefore, it is considered to be an appropriate method to supply standard samples in an indoor air quality proficiency test.

The purpose of this study was to examine the effects of adolescents’ game usage on game addiction and the mediation effects of withdrawal symptoms and loss of control. The subjects of the study was 6,499 elementary, middle and high school students included in the panel data from the survey conducted by The National Youth Policy Institute. For data analysis, SPSS WIN 21 and AMOS 21 programs were used to test the structural equation model by examining the relationships among game usage, withdrawal symptoms, loss of control, and game addiction. The results are as followings. First, adolescents’ average daily game playing hours and average daily game playing hours on holidays caused withdrawal symptoms and loss of control, increasing the possibility of game addiction. However, the relationship between the number of years of playing games and game addiction was not mediated by withdrawal symptoms and loss of control. This implies that playing computer games from young age does not necessarily lead to game addiction unless the students show withdrawal symptoms or lose control.

This study attempts to introduce and develop nature experience program utilizing the instructional mixed reality and examines its effects on creativity and young children in order to overcome the limitations that can be found when young children explore and observe nature. In addition, the purpose of this study is to investigate the change aspects of creativity and nature-friendly ability of young children when experiencing nature with the further activities using the instructional mixed reality. To verify the effect of the instructional mixed reality developed through this process, this study selected 30 young children who are 5 years old in H child care center located in Seoul. As a research tool, creative test of characteristics for children (K-CTC) produced and standardized by Chung Kyung-won (2003) was used to test creativity. As data analysis methods, SPSS 17.0, T-test, MANOVA test, and repeated measure ANOVA were conducted.

This research determined the threshold value of 10 specified offensive odor substances based on the 3 point comparison sensory method. The panelist's thresholds were calculated by taking the arithmetic, geometric mean, and 50th percentile. Three methods of calculating the odor thresholds from the same data are compared. For 10 odor substances, the panelist's thresholds revealed a logarithmically normal distribution. The 50th percentile was the best method among the three methods of calculating the odor threshold from the 270 thresholds of 18 panels. As a result, the threshold values of individual odor substances, including i-valeric acid, n-valeric acid, n-butyric acid, and butyl acetate ranged between 0.0001~0.006 ppm, while the values of methyl ethyl ketone and toluene were relatively higher than that of other substances at 0.7107 ppm and 1.2139 ppm, respectively. The threshold values of the 10 specified odor substances were compared in Korea and overseas, which showed that the characteristics of sensory response varied by substance and nation.

본 연구는 안정동위원소 분석방법을 적용하여, 호소내 식물플랑크톤 성장에 영향을 미치는 외부 오염원의 기원을 추정함으로써, 효율적인 수질 관리 및 수생태계 기능해석을 제공하기 위하여 연구하였다. POC, PN, Chl. a, 탄소 안정동위원소비 및 질소 안정동위원소비의 자료로 유추해 보았을 때, 팔당댐, 남한강, 북한강 지역에 비해서 경안천 지역에서 계절에 따른 유기물의 기원 변동이 뚜렷하게 관찰되고 있다. 유입량 및 강우량이 많은 시기인 7, 8월경에 입자성 유기물의 기원이 자생기원 유기물보다는 외부기원 유기물이 높은 영향을 미치는 것으로 여겨진다. 한강 유역에서 입자성 유기물의 탄소 및 질소 안정동위원소비를 이용한 유기물 기원 연구는 적용가능 할 것으로 여겨지며, 추후 유역 오염원의 대표값(end member)의 지속적인 조사를 통하여 자료구축이 이루어져야 할 것이다.

2011년에 전국 79개 악취검사기관을 대상으로 공기희석관능법에 대한 숙련도 시험을 실시하였다. 악취방지법의 부지 경계선과 악취 배출원의 배출허용기준을 모사한 2개의 합성복합악취를 숙련도 시험물질(proficiency testing materials, PTM)로 사용 하였다. 부지 경계선 시료는 7ppm의 톨루엔과 7ppm m-자일렌의 복합악취로 구성하였으며, 배출구 시 료는 10ppm DMS (dimethyl sulfide)와 10ppm DMDS (dimethyl disulfide)의 복합악취로 구성하였다. 숙련도 시험 결과는 기준값으로 평균과 중간값을 사용하고, 목표표준편차로 일반 표준편차, 로버스트 표준편차 및 변동계수를 사용하여 Z-점수를 평가하였다. 시험결 과의 변동계수는 PTMs의 냄새강도가 증가함에 따라 감소하였다. 복합악취에 대한 숙련 도 시험 결과는 악취희석배율보다 로그 스케일의 악취지수를 사용하여 평가하는 것이 적 절했다. 두 PTMs에 대한 참여기관의 Z-점수를 변동계수, 표준편차, 그리고 로버스트 표 준편차를 사용하여 평가할 때, 참여기관의 95%가 숙련도 기준을 만족하였다. 목표 표준 편차를 변동계수의 20%로 설정하였을 때 참여기관의 만족도 비율은 부지경계와 출구 PTM 시료에 대해 각각 90%와 95%로 양호하였다. 이러한 결과들로부터 부지경계와 출 구의 복합악취를 모사한 두 합성 PTMs 모두 복합악취의 숙련도 시험물질로 적합하였다.

본 연구에서는 악취숙련도 시험을 위한 PTM 물질로 현장시료의 적용가능성을 평가하기 위하여 하수처리장에 채취한 현장시료의 안정성과 채취 균질성을 조사하였다. 또한 현장시료를 PTM으로 사용하여 71개 악취검사기관의 공기희석관능법의 숙련도 시험을 실시하였다. 다양한 설정값(참여기관 또는 기준기관의 악취지수 평균값이나 중위수)를 기준으로 3가지 Z-score 평가법(표준편차 이용한 Z-score, Robust 표준편차를 이용한 Z-score, 목표표준편차를 이용한 Z-score)으로 숙련도의 통계적 분석을 하였다. 하수처리장 농축조에서 채취한 현장시료는 2일 동안 희석배수의 변화 없이 안정적이었고, 참여기관을 4 그룹으로 나누어 순차적으로 채취한 현장시료가 균질한 것으로 평가되었다. 이는 현장악취시료가 악취 숙련도 평가를 위한 PTM 물질로 적용 가능함을 의미한다. 숙련도 시험결과의 통계적 분석을 통해 참여기관의 숙련도 만족비율은 Z-score 평가법이나 설정값의 기준(참여기관 또는 참고기관으로 선택한 3개 대학의 악취지수 평균값이나 중위수) 보다는 목표표준편차(S*ref)값에 의존하였다. 숙련도 만족비율은 S*ref 값이 증가함에 따라 증가하였으며, PTM 시료의 분석결과에 대한 변동계수(CV) 0.13에 해당하는 목표표준편차값에서 숙련도 만족비율은 약 93∼96% 수준이었다.

This study was carried out to provide the stable and homogeneous sample for the proficiency test which was applied for the olfactory dilution method of the offensive odor. For this purpose, the relationship between VOCs concentration and air dilution test results were analysed. As the results, the mixture of 7.1 ppm of toluene and m-xylene were suitable as a low level of PTM(proficiency test material) for air dilution olfactory method. In addition, time stability and homogeneity between samples were investigated through the time of 6 hr ~ 48 hr. As the results, the stability of sample concentration with GC analysis was shown as 5.1% RSD for toluene and 6.8 %RSD for xylene, respectively. The stability of sample was 5.4 %RSD in terms of air dilution olfactory method.

This study was focused on the maximization of flame-retardancy of polyesters by a synergism of simultaneously introduced chlorine and phosphorus into polymer chains of modified polyesters. To prepare modified polyesters, reaction intermediates, TD-adduct (prepared from trimethylolpropane/2,4-dichlorobenzoic acid (2,4-DCBA)) and TMBO (prepared from tetramethylene bis(orthophosphate)), were prepared first, then condensation polymerization of the prepared intermediates, adipic acid, and 1,4-butanediol were carried out. In the condensation polymerization, the content of phosphorus was fixed to be 2%, and the content of 2,4-DCBA that provides chlorine component was varied to be 10, 20, and 30wt%, and we designated the prepared modified polyesters containing chlorine and phosphorus as ABTT-10C, -20C, -30C. Two-component PU flame-retardant coatings (ABTTC, ABTTC-10C, ABTTC-20C, ABTTC-30C) were prepared by the curing of synthesized ABTTs with a curing agent of allophanate/trimer at room temperature. To examine the film properties of the prepared PU flame-retardant coatings, film specimens were prepared with the prepared coatings. The film properties of ABTTC, ABTTC-10C and ABTTC-20C, which contain 0, 10 and 20wt% 2,4-DCBA, respectively, were proved to be good, whereas the film properties of ABTTC-30C, which contains 30wt% 2,4-DCBA, was proved to be a little bit poor. Two kinds of flame retardancy tests, ˚45Meckel burner method and LOI method were performed. With the ˚45Meckel burner method, three flame-retardant coatings except ABTTC showed less than 3.4cm of char length, and showed less than 2 seconds of afterflaming and afterglow. From this result, the prepared flame-retardant coatings were proved to have the 1st grade flame retardancy. With the LOI method, the LOI values of the coatings containing more than 10wt% 2,4-DCBA were higher than 30%, which means that the coatings possess good flame retardancy. From these results, it was found that synergistic effect in flame retardancy was taken place by the introduced phosphorus and chlorine.

To prepare weather-resistant silicone/acrylic resin coatings for an architectural purpose, tetrapolymers were synthesized by a radical polymerization. 3-Methacryloxypropyltrimethoxysilane (MPTS) as a silicone monomer and n-butyl acrylate, methyl methacrylate, and n-butyl methacrylate as acrylic monomers were used. The compositions of monomers were adjusted to fix the glass transition temperature of acrylic polymer for 20℃. The composition of MPTS in the synthesized polymer were varied from 10 wt% to 30 wt%. On the basis of synthesized resin amber paints were prepared and their physical properties and effects for weatherability were examined. The presence of MPTS in silicone/acrylic resins generally resulted in low molecular weight and broad molecular weight distribution, and also lowered the viscosity of the copolymers. The coated films prepared from these resins showed good and balanced properties in general. Adhesion to the substrate was outstanding in particular. Weatherability tests were carried out in three different types such as outdoor exposure, QUV, and SWO. The test results showed that the silicone/acrylic resins containing 30 wt% of MPTS had weather-resistant properties.

The PU flame-retardant coatings (TTBAH, ATBAH-10C, -20C, and -30C) were prepared using the synthesized ATBAs and HDI-trimer as curing agent at room temperature. The physical properties of PU flame-retardant coatings with chlorine and phosphorus were inferior to those with phosphorus only and the properties were getting worse with increasing chlorine content. Flame retardancy was tested with three methods. With the vertical method, complete combustion time of ATBAHs were 259~347 seconds, which means that the prepared coatings are good flame-retardant. With the 45˚ Meckel burner method, char lengths of the three prepared coatings were less than 2.9 cm, which indicates that the prepared coatings are first grade. With the limiting oxygen index (LOI) method, the LOI values of the three prepared coatings were in the range of 30~35%, which proves good flame retardancy of the prepared coatings. from the result of flame retardancy tests of the specimens that contain the same amounts of flame retarding compounds. it was found that the coatings containing both phosphorus and chlorine show higher flame retardancy than the coatings containing only phosphorus. This indicates that there exists, some synergy effect between coexisting phosphorus and chlorine.

In order to prepare high-solid coatings, first acrylic resins (HSAs) which contain 80% solid were synthesized, and then the prepared resins were cured with isocyanate at room temperature. In the synthesis of HSAs, viscosity, number average molecular weight (Mn) and conversion were 1372~2700 cps, 1520~1650 and 83~87%, respectively. Among the four kinds of initiators used, tert-amylperoxy-2-ethyl hexanoate was the most proper one in the synthesis of HSAs. With increasing Tg values, viscosity increased rapidly and molecular weight increased slowly. As a result of the examination of coated films, it was found that 60˚ specular gloss, impact resistance, heat resistance and cross-hatch adhesion were good, and pencil hardness, drying time and pot life were poor.

Methanol and formaldehyde were produced directly by the partial oxidation of methane over mixed oxide catalysts. The catalysts were composed of Mo and Bi with late-transition metals, such as Mn, Fe, and Co. The reaction was carried out at 450℃, 50 bar in a fixed-bed differential reactor. The prepared catalysts were characterized by O2-TPD and BET apparatus. Among the catalysts used, the catalyst composed of 1:1:2.5 molar ratio of Mo:Bi:Mn showed the best methane conversion and methanol selectivity. The change in ratio of methane to oxygen affected at the conversion and selectivity, and the most proper ratio was 10:1.5. Methane conversion, methanol and formaldehyde selectivities increased with the surface areas of the catalysts. From the O2-TPD result, it was found that the oxygen species responsible for this reaction might be the lattice oxygen species desorbed at high temperature around 800℃.

Acrylic adhesives for automobiles protection were prepared by emulsion polymerization. Monomers used were n-butyl acrylate(BA), acrylonitrile (AN), butyl methacrylate(BMA), glycidyl methacrylate(GMA), and acrylic acid (AA). Emulsifiers used were sodium lauryl sulfate and polyoxyethylene lauryl ether, which are an anionic emulsifier and a nonionic emulsifier respectively. Potassium persulfate was used as an initiator and polyvinyl alcohol was used as a stabilizer. Emulsion polymerization was carried out in a semi-batch reactor at 70℃ and agitation speed was kept at 200 rpm. Water resistance, heat resistance, acid resistance, alkali resistance and smoke resistance were examined. As a result, when each 0.03 mole of GMA and AA was introduced, the adhesion properties and various above mentioned resistances of the prepared adhesives were satisfied the standard for automobiles.