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        검색결과 86

        1.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we proposed a novel concept of liquid level indicator that can stably measure the liquid level even with changes in liquid density by enormous temperature changes. This uses a distributed optical fiber sensor based on Rayleigh scattering with high spatial resolution. Additionally, taking advantage of the flexibility of an optical fiber sensor, we introduced a bendable supporting structure and made it possible to freely adjust the angle for ease of installation of the liquid level indicator. In the proof-of-concept experiment using a prototype incorporating the proposed concept, we confirmed that the interface location can be effectively detected by utilizing the difference in heat transfer characteristics between liquid and gas phases, demonstrating the feasibility of liquid level measurement. Such a liquid level indicator is expected to enable more accurate level measurements in environments with huge temperature changes and to be conveniently used even in situations where installation and maintenance of the level meter are challenging due to complex internal structures.
        4,000원
        2.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Maintaining sea superiority through successful mission accomplishments of warships is being proved to be an important factor of winning a war, as in the Ukraine-Russia war. in order to ensure the ability of a warship to perform its duties, the survivability of the warship must be strengthened. In particular, among the survivability factors, vulnerability is closely related to a damage assessment, and these vulnerability data are used as basic data to measure the mission capability. The warship's mission capability is usually measured using a wargame model, but only the operational effects of a macroscopic view are measured with a theater level resolution. In order to analyze the effectiveness and efficiency of a weapon system in the context of advanced weapon systems and equipments, a warship's mission capability must be measured at the engagement level resolution. To this end, not the relationship between the displacement tonnage and the weight of warheads applied in the theater level model, but an engagement level resolution vulnerability assessment method that can specify physical and functional damage at the hit position should be applied. This study proposes a method of measuring a warship’s mission capability by applying the warship vulnerability assessment method to the naval engagement level analysis model. The result can be used as basic data in developing engagement algorithms for effective and efficient operation tactics to be implemented from a single unit weapon system to multiple warships.
        4,200원
        3.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to investigate whether there were differences in eco-friendly food, home meal replacement (HMR) purchases, and eating-out behavior according to the level of agri-food consumer competence. The data for the study were extracted from main food consumers (n=3,321) in the 2022 Food Consumption Behavior Survey. The competence index was divided into awareness-attitude-practice items, and three groups were classified by competence level. The results showed an agri-food consumer competency score of 70.62, with the highest score for awareness (73.96), followed by practice (69.28) and attitude (66.18). The frequency of purchasing eco-friendly food was higher in the excellent group compared to other groups, and quality and price satisfaction was higher with higher competency (p<0.001). Regarding HMR, the results showed that the shortage group had the lowest HMR consumption rate, and satisfaction decreased as competence decreased (p<0.001). The main reason for eating-out was to enjoy food in all groups (59.0%), followed by a lack of cooking time in the excellent group (15.7%) and hassle with food preparation in the moderate and shortage groups (17.3%, 16.6%) (p<0.001). In short, agri-food consumption competency showed differences by contents and components, and differences in food purchases and eating-out behavior by competency level were found.
        5,100원
        4.
        2023.11 구독 인증기관·개인회원 무료
        With the importance of permanent disposal of high-level radioactive waste (HLW) generated in Korea, the deep geological disposal system based on the KBS-3 type is being developed. Since the deep geological repository must provide the long-term isolation of HLW from the surface environment and normal habitats for humans, plants, and animals, it is essential to assess the longterm performance of the disposal facility considering thermal-hydraulic-mechanical-chemical (TH- M-C) evolution. Decay heat dissipated from HLW contained in the canister causes an increase in temperature in the adjacent area. The requirement for the maximum temperature is established in consideration of the possibility of bentonite degradation. Therefore, when designing the repository, the temperature in the region of interest should be identified in detail through the thermal evolution assessment to ensure that the design requirement is satisfied. In the thermal evolution analysis, it is needed to evaluate the temperature distribution over the entire area of the disposal panel to consider the heat generated from both a single canister and adjacent canisters. Computational fluid dynamics (CFD) codes are widely used for detailed temperature analysis but are limited to simulating a wide range. Accordingly, in this study, we developed an analytical solution-based program for efficiently calculating the temperature distribution throughout the deposition panel, which is based on threedimensional heat conduction equations. The code developed can assess the temperature distribution of engineered and natural barrier systems. Principal parameters to be inputted are as follows: (a) geometry of the panel (e.g. width, length, height, spacing between canisters), (b) geometry of the canister (e.g. diameter, height), (c) thermal properties of bentonite and host-rock, (d) initial conditions (e.g. residual heat, temperature), and (e) time information (e.g. canister emplacement rate, time-interval, period). Through the calculation for the conceptual problem of a deposition panel capable of accommodating 900 (i.e. 30×30) canisters, it was confirmed that the program can adequately predict when and where the maximum temperature will occur. It is expected that the overall temperature distribution within the panel can be obtained by the evaluation of the entire region using this program reflecting the detailed design of the repository to be developed in the future. In addition, the thermal evolution analysis considering the influence of other canisters can be performed by applying the results as boundary conditions in the CFD analysis.
        5.
        2023.05 구독 인증기관·개인회원 무료
        Level measurement of liquid radwaste is essential for inventory management of treatment system. Among various methods, level measurement based on differential pressure has many advantages. First, it is possible to measure the liquid level of the system regardless of liquid type. Second, as the instrument doesn’t need to be installed near the tank, there is no need to contact the tank when managing it. Therefore, workers’ radiation dose from the system can be decreased. Finally, although it depends on the accuracy, the price of the instrument is relatively low. With these advantages, in general, liquid radwaste level in a tank is measured using differential pressure in the treatment system. Not only the advantages described above, there are some disadvantages. As the liquid in the system is waste, it is not pure but has some suspended materials. These materials can be accumulated in tanks and pipes where the liquids move to come into direct contact with pneumatic pipes that are essential in differential pressure instruments. As a result, in case of a treatment using heat source, the accumulated materials may become sludge causing interference in pneumatic pipes. And this can change the pressure which also affects the level measured. In conclusion, in case of liquid storage tanks in which the situation cannot be checked, the proficiency of an operator becomes important.
        6.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Adsorption of arsenic by graphene-based adsorbents is widely applied to remove arsenic from water and has become a promising technology. However, most of the reported studies were conducted at a relatively higher concentration of arsenic in As (V) oxidative form, whereas the As (III) is more difficult to remove from water and more toxic, which prompted us to conduct the study at a lower concentration of 1 ppm in As (III). A Facile and controlled synthesis of graphene-based metal/ metal oxide nanomaterials and adsorptive removal of aqueous As (III) is reported here. Adsorbents were characterized using spectroscopy (FTIR, XPS and Raman) and microscopy (TEM). The maximum uptake of arsenic obtained was 88.8% from the RGO-Fe3O4 composite among all the adsorbents. The pseudo-second-order model and Intra-particle mass transfer diffusion model were applied to determine the adsorption kinetics with varying contact time between the adsorbents and the As (III) in water to interact. Experimental results suggest that the adsorption of As (III) onto the adsorbents was a multi-step process involving external adsorption to the surface followed by diffusion to the interior. A simple spectrophotometric method also was used for the detection and quantification of As (III).
        4,200원
        7.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        냉매 오충전은 에어컨에서 빈번하게 발생하는 고장 모드 중 하나로, 적정 충전량 대비 부족 및 과충전 모두 냉방 성능의 저하를 유 발하므로 충전된 냉매량을 정확하게 판단하는 것이 중요하다. 본 연구에서는 퍼지 군집화 기법을 통한 정상상태 식별을 통해 냉매 오 충전량을 다중 분류하는 모델을 개발하였다. 정상상태 식별을 위해 에어컨 운전 데이터에 대해 이동 평균 간의 차이를 활용한 퍼지 군 집화 알고리즘을 적용하였으며, IFDR를 통해 기존 연구된 정상상태 판단 기법들과 식별 결과를 비교하였다. 이후, 시스템 내 상관성 을 고려한 mRMR을 이용해 특징을 선택하였으며, 도출된 특징을 이용해 SVM 기반의 다중 분류 모델이 생성되었다. 제안된 방법은 시험 데이터를 통해 만족할 만한 분류 정확도와 강건성을 도출하였다.
        4,000원
        8.
        2022.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to determine fragility curves, the limit state of piers for each damage level is suggested in this paper based on the previous test results in Korea, including our test results. In previous studies, the quantitative measures for damage levels of piers have been represented by curvature ductility, lateral drift ratio, or displacement ductility. These measures are transformed to lateral drift ratios of piers for consistency, and the transformed values are compared and verified with our push-over test results for flexural RC piers with a circular cross-section. The test specimens are categorized concerning the number of lap-splices in the plastic hinge region and whether seismic design codes are satisfied or not. Based on the collected test results in Korea, including ours, the lateral drift ratio for each pier damage level is suggested.
        4,200원
        14.
        2020.11 구독 인증기관 무료, 개인회원 유료
        The nature of NPD is conducive to SMEs improvising at all stages of the process. This has the potential to create new knowledge, which, if retained and harnessed, can then be applied at higher strategic levels within the firm. This paper examines this phenomenon, through a preliminary qualitative study.
        4,000원
        16.
        2020.06 구독 인증기관 무료, 개인회원 유료
        The aim of this study was to identify strain KCOM 1265 isolated from subgingival plaque at the species level by comparing 16S ribosomal RNA gene (16S rDNA) and genome sequences. The whole genome of strain KCOM 1265 was extracted using the phenol–chloroform extraction method. 16S rDNA was amplified using polymerase chain reaction and sequenced using the dideoxy chain termination method. Pairwise genome comparison was performed using average nucleotide identity (ANI) and genome-to-genome distance (GGD) analyses. The data showed that the percent similarity of 16S rDNA sequence of strain KCOM 1265 was 99.6% as compared with those of Fusobacterium polymorphum ATCC 10953T and Fusobacterium hwasookii KCOM 1249T. The ANI values of strain KCOM 1265 with F. polymorphum ATCC 10953T and F. hwasookii KCOM 1249T were 95.8% and 93.0%, respectively. The GGD values of strain KCOM 1265 with F. polymorphum ATCC 10953T and F. hwasookii KCOM 1249T were 63.9% and 49.6%, respectively. These results indicate that strain KCOM 1265 belongs to F. polymorphum.
        4,000원
        17.
        2020.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본고는 교과의 하나인 한문과의 정의・의미・특징을 바탕으로, 교사 차원의 한문 수업 교육목표 및 교육내용 설계에의 시사점을 발견하는 것을 목표로 한다. 이를 위해 먼저 교과 한문과의 정의와 의미를 살펴보고, 이를 바탕으로 교육적 보편성 및 교과적 특수성・맥락의존적・유동적・목적지향적・가치지향적인 특징을 유추하였다. 이를 바탕으로 한문 수업의 교육목표 및 교육내용 설계에의 시사점을 다음과 같이 발견하였다. 첫째, 교육적 보편성과 교과적 특수성을 동시에 고려하여야 한다. 둘째, 학교 교육이라는 구체적 맥락에 존재하는 사회, 학습자의 요구에도 관심을 가져야 한다. 셋째, 기존에 선정된 교육목표 및 교육내용에 대한 검토가 필요하다. 넷째, 핵심 교육목표의 설정이 필요하다. 다섯째, 교육내용에 있어서는 핵심 지식에 대한 구명이 필요하다.
        7,700원
        18.
        2020.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study examined how teaching and learning activities in primary English textbooks include the components of creativity and character building. Three third and fourth grade level textbooks based on the 2015 revised curriculum were analyzed in order to find the proportions of the components of creativity and character building, and the types of learning activities that embody those components were analyzed by examining the teachers’ guides. The analysis revealed that all of the textbooks examined included diverse components that were intented to increase creativity, among which components stimulating divergent thinking and originality were a high proportion, while convergent thinking and dispositional aspects appeared less frequently. Among character building components, care-forgiveness and responsibility were two of the more popular components, while honesty and moral judgment were few and far between. From these findings, this study suggests that the components of creativity and character building should be more evenly distributed across textbook activities since they should be of equal importance in education.
        6,900원
        19.
        2019.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        국내 고준위 방사성폐기물 심층처분시스템에 대한 프로세스 기반의 종합성능평가체계(APro) 개발을 위하여 사용자 편의성이 향상된 모델링 인터페이스를 구축하였다. APro의 모델링 인터페이스는 프로그래밍 언어인 MATLAB을 이용하여 구축되었고, 다중물리현상 모사가 가능한 COMSOL과 지화학반응 계산이 가능한 PHREEQC를 계산 엔진으로 활용하여 연산 자분리 방식을 적용하였다. APro는 모델링 영역을 기존의 정형화된 처분시스템으로 제한함으로써 모델의 자유도는 낮지만, 사용자 편의성을 향상시켰다. 처분시스템에서 고려되는 주요 현상들을 모듈화하였고, 이를“Default process”와 다수의“Alternative process”로 구분하여 사용자가 선택할 수 있도록 함으로써 모델의 유연성을 높였다. APro는 크게 입력자료 부분과 계산실행 부분으로 구성된다. 기본 입력자료는 하나의 EXCEL 파일에 일정한 포맷으로 정리되고, 계산실행 부분은 MATLAB을 이용하여 코딩되었다. 최종적인 전체 계산 결과는 독립적인 COMSOL 파일 형태로 생성되도록 하여 COMSOL을 이용한 계산 결과의 후처리가 가능하도록 하였다.
        4,000원
        20.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Purpose: This study investigated the dietary patterns associated with Korean food and the level of proper eating habits according to recognition of the Kimchi cooking method, and aimed to suggest the necessity of dietary education of traditional foods such as Kimchi. Methods: Based on the results of the national dietary survey conducted in 2014 by Ministry of Agriculture, Food and Rural Affairs of Korea, a total of 1200 subjects were classified into two groups, one that knew how to make Kimchi (53.8%) and another that did not (46.2%). Results: The group that knew how to make Kimchi (FG) showed significantly higher scores in knowledge of how to cook most types of Korean foods and traditional fermented foods than the other group (NG). Moreover, FG showed significantly higher scores in regularity in meals and a higher frequency of Korean foods such as rice, Kimchi, and grilled or stewed food, while it showed significantly lower scores in dietary risk factors than NG. In addition, FG showed significantly higher scores in dietary education interest and number of meals with family during the week than NG. Finally, FG had significantly higher scores in the degrees of practice of all eight items related to proper eating habits. Conclusion: Since recognition of Kimchi cooking has a great influence on maintenance of dietary life, dietary education to improve the cooking ability of traditional foods should be further strengthened.
        4,200원
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