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        검색결과 18,165

        4302.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The aim of the present work was to develop simultaneous methods of quantification of carazolol, azaperone, and azaperol residues in livestock and fishery products using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Samples were extracted from beef, pork, chicken, egg, milk and shrimp using acetonitrile (ACN); while flat fish and eel were extracted using 80% ACN. For purification, ACN saturated n-hexane was used to remove fat composition. The standard calibration curves showed good linearity as correlation coefficients; r 2 was > 0.99. Average recoveries expressed were within the range of 67.9-105% for samples fortified at three different levels (0.5 × MRL, 1 × MRL and 2 × MRL). The correlation coefficient expressed as precision was within the range of 0.55- 7.93%. The limit of quantification (LOQ) was 0.0002-0.002 mg/kg. The proposed analytical method showed high accuracy and acceptable sensitivity based on Codex guideline requirements (CAC/GL71-2009). This method can be used to analyze the residue of carazolol, azaperone, and azaperol in livestock and fishery products.
        4,000원
        4303.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The use of microwave-assisted extraction and an acid-base clean-up process to determine the amount of methylmercury (MeHg) in marine products was suggested in order to improve the complicated sample preparation process. The optimal conditions for microwave-assisted extraction was developed by using a 10% NaCl solution as an extraction solution, setting the extraction temperature at 50℃, and holding for 15 minutes to extract the MeHg in marine products. A NaOH solution was selected as a clean-up substitute instead of L-cysteine solution. Overall, 670 samples of marine products were analyzed for total mercury (Hg). Detection levels were in the range of 0.0006~0.3801 μg/kg. MeHg was analyzed and compared using the current food code and the proposed method for 49 samples which contained above 0.1 mg/kg of Hg. Detection ranges of methylmercury followed by the Korea Food Code and the proposed method were 75.25 (ND~516.93) μg/kg and 142.07 (100.14~244.55) μg/kg, respectively. The total analytical time of proposed method was reduced by more than 25% compared with the current food code method.
        4,000원
        4304.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        저어새의 먹이생물을 파악하기 위해 2010년 6월부터 2014년 6월까지 인천 남동유수지에서 저어새의 토사물 시료를 채집하여 현미경 관찰 및 차세대염기서열 (NGS) 기법으로 분석 하였다. 저어새의 먹이생물은 어류, 갑각류, 다모류, 곤충류로 구성되어 있었으며, 주로 저어새는 어류와 갑각류를 섭이하는 것으로 나타났다. 최우점 먹이생물은 풀망둑 (Acanthogobius hasta)이었으며, 이 외에도 길게 (Macrophthalmus abbreviates), 징거미새우류 (Macrobrachium sp.), 칠게 (Macrophthalmus japonicus), 각시흰새우 (Exopalaemon modestus), 참 갯지렁이 (Neanthes japonica)가 우점 먹이생물로 출현하였다. 이들 먹이생물은 번식지 인근지역인 송도갯벌과 시화호에서 흔히 발견되며, 저어새는 채식지로써 이들 지역에 대한 의존도가 높을 것으로 판단된다. 현미경과 NGS로 분석한 일부 먹이생물에서 차이를 보였는데, 이는 토사물 내 먹이생물은 저어새의 위 내에서 분해되어 현미경 분석을 통한 형태학적 분류 특징을 찾기 어려웠던 반면, NGS 분석은 유전자를 통해 분류가 가능하기 때문에 형태학적 분석의 결과보다 높은 종 다양성을 보인 결과이다.
        4,000원
        4305.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study investigates secondary school student athletes’ specific needs for English learning and analyzes correlation and a cause and effect relationship among the needs-related variables. Two hundred forty six student athletes enrolled in physical education. Junior and senior high schools participated in the study. Data were collected through a survey that inquired about the students’ perceived English ability and learning areas of interest, their needs for ESP education, and aspects to be considered for ESP course design. The results show that the students put more emphasis on verbal communication (i.e., on speaking and listening) than on written communication (i.e., on reading and writing) and that they wanted more practical ESP education reflecting their needs and interests. Additionally, there was significant correlation (p<.01) among the subjects’ learning areas of interest, needs for ESP education, and aspects to be considered for ESP course design; a cause and effect relationship among the above three variables was discovered by goodness of fit test for structure equation model. Based on these findings, it is concluded that secondary school student athletes’ perceived English ability and areas of interest for English learning influence both their needs for ESP education and aspects to be considered for ESP course design.
        6,000원
        4306.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The proliferation of information technologies made it possible to produce information products of different versions at much lower cost comparing to traditional physical products. Thus it is common for information product manufacturers to consider vertically differentiated product line for more profit through improved market coverage. Another salient characteristic of most information product is network externality. Existing researches dealing with vertical differentiation and network externality usually assumed oligopolistic market where vertically differentiated products are provided by competing companies, respectively. Moreover, they analyzed the essentially dynamic characteristic of network externality statically. In this study, different from the previous researches, the vertical differentiation strategy of a monopolistic company under network externality is dynamically analyzed. We used a two-period model to accommodate the dynamic feature of network externality. Based on the two-period model, the profit maximizing solutions are analyzed. The results showed that a monopolistic company has no incentive to differentiate products vertically when the network externality is absent. On the contrary, when the network externality exists, the monopolistic company can derive more profit by vertically differentiating the product line. It is also shown that, for more profit, the monopolistic company should keep the quality difference between the high quality product and the low quality product as greater as possible.
        4,000원
        4308.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Twenty-nine wetlands (20 river type and 9 lake type wetlands) in Gyeongsangnam-do were investigated to understand the characteristics of fish assemblages by the wetland type and to suggest management strategies. As a result, 10.3±4.8 species were collected from river type wetlands on average (±SD) and 9.1±4.1 species from lake type wetlands. Thus, there was no significant difference in the number of species between them (Mann-Whitney U test, P>0.05). However, the species that constitute the fish assemblage showed statistically significant differences between the two wetland types (PERMANOVA, Pseudo-F=2.9555, P=0.007). Furthermore, the species that contribute the most to each type of fish assemblage were Zacco koreanus (river type, 28.51%) and Lepomis macrochirus (lake type, 23.21%), respectively (SIMPER). The results of the NMDS analysis using the fish assemblage by place classified the species into three groups (river type, lake type, and others). The current wetland management is only focused on endangered species, but this study shows a difference in fish assemblage by wetland type. Therefore, a management system based information on endemic species, exotic species and major contribution species should be provided. Furthermore, the classification of some types of wetlands based on the present topography was found to be ambiguous, and wetland classification using living creatures can be used as a complementary method. This study has limitations because only two types of wetlands were analyzed. Therefore, a detailed management method that can represent every type of wetland should be prepared through the research of all types of wetlands in the future.
        4,200원
        4309.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        콘크리트 구조물 표면에 발생하는 균열은 사용자에게 심리적인 불안감을 제공하며, 장기간 열려있는 큰 폭의 균열은 구조 물의 사용성능 및 내구성에 영향을 준다. 국내에서는 건축물을 포함한 시설물의 노후화에 따른 안전관리를 위해 균열정도를 파악하는 조사가 인력에 의한 육안조사로 수행되고 있지만 인력의 고비용성과 객관성 미흡 등의 문제점이 대두되고 있다. 이를 해결하기 위해 영상분석을 통한 균열 추출 등 다양한 연구가 수행되고 있으나 균열인식 정확도 향상에 2차원 영상 분석만으로는 한계가 있다. 따라서, 본 연구에서는 기존 2차원 영상 분석의 한계를 극복하기 위하여 3차원 특성을 정확하게 파악할 수 있는 3차원 광삼각 스캐닝기법을 활용하여 콘크리트 구조물 표면의 균열정보를 획득하는 기법을 개발하였다. 본 하 드웨어의 개발과 더불어 균열 패턴분석을 위한 획득된 균열의 세분화와 균열의 특성분석 알고리즘을 개발하였으며, 이를 실제 콘크리트 빔의 균열 탐지 적용을 통해 검증하였다.
        4,000원
        4311.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Odor dispersion from road emissions were investigated using CFD (Computational Fluid Dynamics). The Shear Stress Transport k-ω model in FLUENT CFD code was used to simulate odor dispersion around the road. The two road configurations used in the study were at-grade and fill road. Experimental data from the wind tunnel obtained in a previous study was used to validate the numerical result of the road dispersion. Five validation metrics are used to obtain an overall and quantitative evaluation of the performance of Shear Stress Transport k-ω models: the fractional bias (FB), the geometric mean bias (MG), the normalized mean square error (NMSE), the geometric variance (VG), and the fraction of predictions within a factor of two of observations (FAC2). The results of the vertical concentration profile for neutral atmospheric show reasonable performance for all five metrics. Six atmospheric stability conditions were used to evaluate the stability effect of road emission dispersion. It was found that the stability category D case of at-grade decreased the non-dimensional surface odor concentration smaller 0.78~0.93 times than those of stability category A case, and that F case decreased 0.39~0.56 times smaller than those of stability category A case. It was also found that stability category D case of filled road decreased 0.84~0.92 times the non-dimensional surface odor concentration of category A case and stability category F case decreased 0.45~0.58 times compared with stability category A case.
        4,000원
        4314.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To analyze the synergistic effects of applying lavender aroma to a footbath, we analyzed the EEG and emotional responses of footbath, lavender inhalation, and lavender footbath in women in their 30s. Foot baths reduced wave activation, wave and wave inactivation, and SEF50 and SEF90. The foot bath activated waves by about 66% compared to the background EEG, and reduced SEF50 and SEF90 by 0.43 Hz-0.68 Hz and 3.7 Hz, respectively. Lavender inhalation activated α, β, and γ waves at a concentration of 1% or more, and inactivated θ waves. As the concentration of lavender inhalation increased, α waves increased and β and γ waves decreased. Lavender foot bath activates θ waves and α waves, and inactivates β waves and γ waves. Compared with the background EEG, the lavender foot baths reduced SEF50 and SEF90, which are the median frequencies of EEG power, 0.5 Hz and 3.4 Hz, respectively. Lavender showed a positive emotional response when applied to inhalation and foot bath. Lavender showed a positive emotional response when applied to inhalation and foot bath. When the lavender was inhaled at the concentration of 1~10% and the lavender foot bath was applied, the average preference index (API) showed 0.64~0.66 and 3.6 ± 0.6, respectively. Lavender oil has a greater synergistic effect on emotional reactions when applied to an aromatherapy bath than by inhalation. Lavender decreased SEF50 and SEF90 as the API increased. A lavender footbath was superior to lavender inhalation in both emotional and EEG responses, and was more relaxed and calming than a footbath. These results suggest that the aroma foot bath method, in which lavender is applied to a footbath, is more effective in terms of providing relaxation and calming than a footbath or lavender inhalation aromatherapy.
        4,000원
        4316.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 커피(C. Arabica)의 FT-IR 스펙트럼 데이터 를 기반한 다변량통계분석을 이용한 대사체 분석을 통해 품종 식별을 하여 육종 연구에 기초자료로 활용하고자 한다. 1. FT-IR 스펙트럼 데이터를 이용한 PCA(principal component analysis), PLS-DA(partial least square discriminant analysis) 그리고 HCA(hierarchical clustering analysis) 분석을 통해 품종 분류가 가능하였다. 2. 커피 품종들은 FT-IR 스펙트럼 부위인 1700-1500-1 (Amide I 과 II을 포함하는 아미노산 및 단백질계열의 화합물 들), 1500-1300-1 (phosphodiester group을 포함한 핵산 및 인지질의 정보), 1100-950cm-1 (단당류나 복합 다당류를 포함하는 carbohydrates 계열의 화합물)에서 질적, 양적 정보의 차이가 나타났다. 3. PCA 상에 나타난 8품종의 커피 품종이 각각 그룹을 형성하였다. 그 중 ‘Caturra’와 ‘Mahsellesa’ 품종은 각각의 그룹을 나타내면서 C. arabica 종에서도 다른 대사체 정보를 나타내는 것으로 확인하였고, ‘Catuai’, ‘CR-95’, ‘Geisra’, ‘Obata’, ‘Vemecia’ 그리고 ‘non’ 품종은 유사한 대사체 정보를 나타내는 것으로 확인하였다. 4. PLS-DA 분석의 경우 PCA 분석 보다 커피 품종간 식별이 뚜렷하게 나타났다. 5. 본 연구에서 확립된 대사체 수준에서 커피의 품종 식별 기술은 품종, 계통의 신속한 선발 수단으로 활용이 가능할 것으로 기대되며 육종을 통한 품종개발 가속화에 기여 할 수 있을 것으로 예상된다.
        4,000원
        4317.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        There always exist nonzero inspection errors whether inspectors are humans or automatic inspection machines. Inspection errors can be categorized by two types, type I error and type II error, and they can be regarded as either a constant or a random variable. Under the assumption that two types of random inspection errors are distributed with the “uniform” distribution on a half-open interval starting from zero, it was proved that inspectors overestimate any given fraction defective with the probability more than 50%, if and only if the given fraction defective is smaller than a critical value, which depends upon only the ratio of a type II error over a type I error. In addition, it was also proved that the probability of overestimation approaches one hundred percent as a given fraction defective approaches zero. If these critical phenomena hold true for any error distribution, then it might have great economic impact on commercial inspection plans due to the unfair overestimation and the recent trend of decreasing fraction defectives in industry. In this paper, we deal with the same overestimation problem, but assume a “symmetrical triangular” distribution expecting better results since our triangular distribution is closer to a normal distribution than the uniform distribution. It turns out that the overestimation phenomenon still holds true even for the triangular error distribution.
        4,900원
        4318.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this research synthesis, a total of 313 studies on English learning motivation published in South Korea from 2000 to 2017 were reviewed. The data were categorized into four criteria: publication year, research method, participant, and research topic. First, the annual trend clearly demonstrated that the number of motivation research showed a steady growth. The dominant research method was quantitative (207 papers) over qualitative (40 papers) and mixed methods (48 papers). University students (157 papers) were major population in English learning motivation research followed by junior high (36 papers), elementary (30 papers), high school students (30 papers), research synthesis (17 papers), and kindergarten students (3 papers). Most research focused on identifying specific subcomponents of English learning motivation in a particular research context. The study suggests that future research needs to focus more on diverse student group such as home-schoolers. Also, the use of research synthesis needs to be encouraged in order to capture the complex nature of English learning motivation.
        6,300원