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        검색결과 80

        1.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Environmental issues such as global warming due to fossil fuel use are now major worldwide concerns, and interest in renewable and clean energy is growing. Of the various types of renewable energy, green hydrogen energy has recently attracted attention because of its eco-friendly and high-energy density. Electrochemical water splitting is considered a pollution-free means of producing clean hydrogen and oxygen and in large quantities. The development of non-noble electrocatalysts with low cost and high performance in water splitting has also attracted considerable attention. In this study, we successfully synthesized a NiCo2O4/NF electrode for an oxygen evolution reaction in alkaline water splitting using a hydrothermal method, which was followed by post-heat treatment. The effects of heat treatment on the electrochemical performance of the electrodes were evaluated under different heat-treatment conditions. The optimized NCO/NF-300 electrode showed an overpotential of 416 mV at a high current density of 50 mA/cm2 and a low Tafel slope (49.06 mV dec-1). It also showed excellent stability (due to the large surface area) and the lowest charge transfer resistance (12.59 Ω). The results suggested that our noble-metal free electrodes have great potential for use in developing alkaline electrolysis systems.
        4,000원
        2.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, based on the existing research, we define the parameters for the number of ignition devices to be applied to the pyrovalve, the operation and airtightness according to the temperature, the material of the nipple and the thickness of the fractured part, and ANSYS Ver. 19.2 was used to analyze the FEA model, and a comparative analysis was conducted through structure analysis according to the piston shape of the pyrovalve. In addition, an experimental study was conducted by manufacturing a prototype according to the design variables. As a result, high-strength pyrovalves can stably supply working fluids such as fuel and oxidizer for space launch vehicle propulsion engines, as well as precisely control flow path switching was confirmed.
        4,000원
        3.
        2022.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Valves are one of the indispensable components in modern industry. Filling and de-pressure connectors in rocket valves used for space launch vehicles are very important parts for smooth fluid supply. For this reason, an optimized design that can improve efficiency, miniaturization, weight reduction, and safety of the valve at the same time is required. In this work, flow analysis and structural analysis were performed through 3D modeling using computational numerical analysis for open type filling and de-pressure valves. As results, the flow velocity and pressure distribution of the fluid were analyzed through the flow analysis of valve, and stress distribution was conducted in structural analysis. Through this study, it is consequently expected to provide valves of various specifications by performing production and performance test evaluation of development prototypes.
        4,000원
        4.
        2020.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 신흥국 기업이 국제인수합병 시 최고경영자의 정치적 연계가 기업가치에 미치는 영향을 살펴보는데 그 목적을 두고 있다. 기존의 연구들에서는 국제인수합병 시 인수기업 최고경영자의 정치적 연계가 기업가치에 미치는 영향에 관해 혼재된 결과를 제시하였다. 국제인수합병 시 인수기업 최고경영자가 갖고 있는 정치적 연계는 전략적 자원으로서 투자자들에게 긍정적인 시그널을 주지만 정치적 연계로 인해 생기는 정부-기업간 이익충돌 문제는 투자자들에게 부정적인 시그널을 주기 때문이다. 따라서 신흥국 기업 최고경영자의 정치적 연계가 국제인 수합병 시 기업가치에 미치는 영향을 보다 명확히 분석하기 위해 본 연구는 제도적 관점을 적용하여 시장 환경의 조절효과를 보여준다. 본 연구는 중국 상장기업이 2008년부터 2016년까지 진행한 국제인수합병 359개 사례를 표본으로 실증연구를 진행하였다. 그 결과 국제인수합병 시 인수기업 최고경영자의 정치적 연계는 정부의 지대추구 행위(rent-seeking behavior)로 인해 정부와 기업 사이 주인간 갈등(principal-principal conflict) 문제를 일으켜 투자자들에게 부정적인 시그널을 주어 기업의 시장가치에 단기적으로 부정적인 영향을 미치는 것으로 나타났다. 하지만 중국 인수기업이 위치한 지역의 시장화 정도가 높을수록 투자자들은 정치적 연계와는 상관없이 기업의 행위를 더욱 객관적으로 판단할 수 있기 때문에 국제인수합병 시 최고경영자의 정치적 연계가 기업가치에 미치는 부정적인 영향 은 약화되는 것으로 확인되었다. 반면 피인수기업이 위치한 투자국 거버넌스가 좋을수록 최고경영자의 정치적 연계 는 인수기업의 부정적인 이미지를 부각하여 국제인수합병 시 최고경영자의 정치적 연계가 기업가치에 미치는 부정적인 영향은 강화되는 것으로 확인되었다. 본 연구의 결론과 시사점 그리고 한계점에 관해서는 논문 마지막 부 분에 정리하였다.
        5,800원
        7.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to find out an alternative way of rapid and accurate analysis of chemical composition of permanent pastures in hilly grazing area. Near reflectance infrared spectroscopy (NIRS) was used to evaluate the potential for predicting proximate analysis of permanent pastures in a vegetative stage. 386 pasture samples obtained from hilly grazing area in 2015 and 2016 were scanned for their visible–NIR spectra from 400~2,400nm. 163 samples with different spectral characteristics were selected and analysed for moisture, crude protein (CP), crude ash (CA), acid detergent fiber (ADF) and neutral detergent fiber (NDF). Multiple linear regression was used with wet analysis data and spectra for developing the calibration and validation mode1. Wavelength of 400 to 2500nm and near infrared range with different critical T outlier value 2.5 and 1.5 were used for developing the most suitable equation. The important index in this experiment was SEC and SEP. The R2 value for moisture, CP, CA, CF, Ash, ADF, NDF in calibration set was 0.86, 0.94, 0.91, 0.88, 0.48 and 0.93, respectively. The value in validation set was 0.66, 0.86, 0.83, 0.71, 0.35 and 0.88, respectively. The results of this experiment indicate that NIRS is a reliable analytical method to assess forage quality for CP, CF, NDF except ADF and moisture in permanent pastures when proper samples incorporated into the equation development.
        4,000원
        8.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of study was to find the relationship in hilly pasture landscape expectancy and tourist’s satisfaction on grassland facility. It was followed by literature reviews and visitors’ survey in Daegwallyeong Yangtte Farm on 31, July, 2014. 367 respondents were analyzed by F-test, t-test, Chi-square and Fisher’s Exact Test at 0.05 level after data screening process. Computing factors were sex, marital status, age, academic career and occupation. The results was as followed; First, major respondents group of survey were in oder of woman, forty years old group, married office worker, and university graduate. Second, the expectancy for grassland was significant difference in age, but pasture color expectancy was not significant difference in gender, age, educational background, marital status, and there was significant difference in favorite grassland type with age, marital status. Third, favorite fence type was not significant difference along with all group of participants. However, color and material of fence was significant difference in marital status. Fourth, preferred ranch road was significant difference with occupation and marital status. There was significant difference in favorite grassland type near ranch road along with age and occupation type. Fifth, the mean satisfaction was 3.6 point in 5.0. Therefore, all respondents were generally satisfaction in visited. Tourists were more interested in ranch landscape than experience or contacts to animal.
        4,300원
        9.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Red sorrel (Rumex acetosella L.), as one of exotic weeds in Korea, was dominated in grassland and reduced the quality of forage. Improving current pasture productivity by precision management requires practical tools to collect site-specific pasture weed data. Recent development in unmanned aerial vehicle (UAV) technology has offered cost effective and real time applications for site-specific data collection. To map red sorrel on a hill pasture, we tested the potential use of an UAV system with digital cameras (visible and near-infrared (NIR) camera). Field measurements were conducted on grazing hill pasture at Hanwoo Improvement Office, Seosan City, Chungcheongnam-do Province, Korea on May 17, 2014. Plant samples were obtained at 20 sites. An UAV system was used to obtain aerial photos from a height of approximately 50 m (approximately 30 cm spatial resolution). Normalized digital number values of Red, Green, Blue, and NIR channels were extracted from aerial photos. Multiple linear regression analysis results showed that the correlation coefficient between Rumex content and 4 bands of UAV image was 0.96 with root mean square error of 9.3. Therefore, UAV monitoring system can be a quick and cost effective tool to obtain spatial distribution of red sorrel data for precision management of hilly grazing pasture
        4,000원
        10.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to study the effect of barley, Italian ryegrass (IRG), and legume mixture on nitrogen fixation and transfer to grasses on spring paddy field, an experiment was carried out from Oct. 2006 to June 2007 in Naju, Korea. A split plot design with three replications was used for the experiment. One reference plot was assigned for each treatment to determine nitrogen fixation. Main plots consisted of Chinese milk vetch, crimson clover, forage pea, and hairy vetch with barley, respectively. Subplot treatment were barley or IRG with four seeding ratio of legumes (50:50, 60:40, 70:30, and 80:20). To estimate N fixation by legumes, 15N isotope dilution technique was used. 15N fertilizer [(15NH4)2SO4 solution at 99.8 atom N] was uniformly applied to 600 cm2 in the middle of each plot on April 15, 2007. Plots were harvest by hand on June 8, 2007. Dried sample were ground to a fine power and analyzed for total N isotope N. 15N was determined using elemental analyzer-isotope ratio mass spectrometry. The calculation of N transfer was determined with the isotope dilution method. The content of N was higher in legumes than that in barley or Italian ryegrass. Nitrogen level in forage pea was significantly higher than that of other legumes. There were significantly differences in N content between legumes in IRG mixture. Atom % 15N excess was significantly different in legumes with barley. The 60:40 sub plot had higher (p<0.05) atom % 15N than other seeding ratio treatments. The enrichment ranged from 0 to 0.58. Compared to barley, the enrichment of IRG with its accompanied legumes was higher, ranging from 0.38 to 1.0. The N derived from the atmosphere (Ndfa) ranged from 0% to 49.5% with barley-legume mixture. It ranged from 0 to 60.5% in IRG-legume plots. N transfer from legumes to neighboring grasses was 12.3 to 90.9 kg/ha for barley-legume mixture and 31.7 to 107.8 kg/ha for IRG plots. IRG plots showed higher N transfer for IRG-legume mixture in general based on difference method. Based on 15N dilution method, the N transfer was 0 to 36.1 kg/ha for barley-legume mixture and 0 to 50.6 kg/ha for IRG plots. There was a tendency toward higher N transfer on the difference method than that of the 15N dilution method.
        4,000원
        11.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to find out the effects of Improvement of Botanical Composition Technology (IBCT) on the forage production and ecological characteristics in a Rumex acetosella-dominated hilly pasture in Pyeongchang, in a period from August 2013 to the end of growing season in October 2015. 2MT ha-1 limestone was applied in August 2013 and April 2014. Liming significantly increased soil pH from 4.69 to 5.47 and then the soil pH consistently hovered at 4.91~4.98. For every grazing time, plant height was found to be higher with the application of IBCT as compared with the control. After grazing, no significant difference in plant height was found between the IBCT group and the control. Changes in the botanical composition of grassland can be affected by a lot of circumstances, but application of IBCT decreased Rumex acetosella from 12% to 2%, while also increasing the proportion of pasture. In relation to the botanical composition of grass, orchardgrass and timothy showed the highest percentages throughout the whole study period. The proportion of Kentucky bluegrass increased over time while tall fescue steadily decreased. The totals for grazing days were 58 in 2014 and 55 in 2015. Average herbage dry matter intake was 7,848 kg ha-1 in 2014 and 6,941 kg ha-1 in 2015. Due to the application of IBCT, dry matter productivity showed a significant increase of 59% during the first grazing period in 2014 (3,437 kg ha and 5,460 kg ha in control and IBCT). In 2015, the total dry matter yield of the IBCT group was 51% greater than the control (5,742 kg ha-1 and 8,685 kg ha-1 in control and IBCT). Under acidic soil conditions, red sorrel can grow more strongly than grasses because it has better tolerance in dry and acidic conditions. Therefore, constant management is required in order to keep red sorrel from dominating the hilly pasture. In this study, the application of IBCT was able to effectively control weeds at all points. As a result, total management, including improvement of soil, overseeding, and application of selective herbicide and fertilizer, is needed to maintain excellent grassland conditions due to the limiting effects of environmental factors on grassland productivity.
        4,000원
        12.
        2016.05 구독 인증기관 무료, 개인회원 유료
        Since the expectations and demand for higher ride comfort of the customers (driver and passengers) have been dramatically increased, new vehicle model launched on the market have not only better performance and design-wise appealing, but also ride comfort has to be increasingly better than its predecessor. Automotive manufactures have focused on the increasing human thermal comfort. To achieve a high thermal comfort, most manufacturers provide a system for their cars to ensure ventilation, heating and cooling air in the passenger compartment. As results, the influence of the seats and situations in the thermal human comfort are considered. And, the temperature distribution pattern on the human face is acquired at natural condition, both warm condition on which seat is managed around 30℃ and hot condition on which seat is managed around 50℃.
        3,000원
        13.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        연구에서는 초등학교 고학년 아동을 대상으로 슬로라이프 에 기반을 둔 식생활교육 프로그램을 개발한 후 실제 적용 하여 그 효과성을 검증하고자 하였다. ADDIE 교수체제개발 모형을 적용하여 분석, 설계, 개발, 실행, 평가의 과정을 거 쳐 체계적인 5차시의 교육 프로그램을 개발하였다. 경기도 남양주시 소재의 Y초등학교 교육군 130명을 대상으로 프로 그램을 적용하였으며, 같은 소재의 J초등학교의 같은 학년 100명을 대조군으로 구성하여 프로그램의 효과성 여부를 평 가하였다. 연구결과를 요약하면 다음과 같다. 1) 초등학교 고학년 아동을 대상으로 올바른 식생활의 주 체적인 실천을 도모하기 위하여 슬로라이프에 기반을 둔 식생활교육 프로그램을 개발하였다. 프로그램은 아동 개인의 건강한 음식에 대한 인식 및 건강한 식생활 실천, 가정에서 의 가족식사를 통해 배려하고 감사하는 식생활 실천, 지역사 회의 농업의 중요성을 깨닫고 환경을 사랑하는 식생활 실천, 전통문화의 우수성을 깨닫고 전통음식을 즐기는 식생활의 실 천을 목표로 그 내용을 구성하였다. 또한 초등학교 아동의 특성을 반영하여 이야기하기 활동, 시각적 자료 등을 이용한 이론 학습 활동, 식재료를 이용한 감각체험 활동, 조리·조 형 활동 등 체험활동 위주의 교육 방법을 활용하였다. 연구 에서 개발된 슬로라이프 교육 프로그램의 실제 활용 가능성여부 파악을 위해 초등학교 고학년 아동을 대상으로 프로그 램을 적용하였다. 2) 교육 프로그램의 효과 판정을 위하여 확장된 계획행동 이론(TPB)의 변수를 이용하여 교육군과 대조군의 교육 전· 후 차이를 비교하였다. 교육 전, 동질성 검증을 통해 지식 변수를 제외한 나머지 변수에 있어서 두 그룹은 유의적으로 다 르지 않음을 확인하였다. 그러나 교육 후 교육군은 모든 계 획행동이론(TPB) 변수에 있어서 유의적 변화(p< .01)가 나타난 반면, 대조군은 지식 및 행동 의도에 있어서만 약간의 유의적 차이(p< .05)가 나타나 교육에 의한 효과를 증명할 수 있었다. 3) 확장된 계획행동이론(TPB) 모형의 적합도 검정을 통해 초등학교 고학년 아동의 슬로라이프 식생활 실천 행동에 미 치는 요인을 분석하고 행동 변화를 예측한 결과, 태도와 지 각된 행동통제, 행동 중요도 변수는 행동 의도의 선행 요인 이 되고, 지각된 행동통제와 행동 중요도, 행동 의도는 행동 에 영향을 미치는 요인이 되는 것으로 확인되었다. 그러나 지식과 주관적 규범이 행동 의도의 독립 변수가 되지 못하 는 것으로 나타났다. 식생활교육의 목적이 지식 향상과 더불 어 바람직한 식습관을 형성하는 것임을 고려하였을 때 5주 간의 교육은 아동의 식생활 습관 전반에 걸쳐 행동의 변화 를 유도하기에는 짧은 기간으로 생각되어 연구의 한계를 나타낸다. 연구에서 보인 확장된 계획행동이론(TPB)의 행동 변 수의 변화는 일시적일 수 있다는 점에 근거하여 긍정적인 효과의 지속 여부를 명확히 밝히기 위해 추후 반복적인 교육 과 유사 연구의 필요성이 제기된다. 교육의 효과성 검증을 위해 확장된 개념의 계획행동이론 (TPB)을 적용하였으나 교육 내용과의 일치 및 변수에의 적용 등을 고려하여 검증되지 못한 측정도구를 사용한 데에 있어서 연구의 한계를 나타냈다. 추후 개발되는 식생활교육 프 로그램의 효과성을 판단하기 위한 다양한 접근법 및 이론을 적용한 측정도구의 개발이 요구된다. 연구에서 개발된 슬로라이프 식생활교육 프로그램이 초등 학교 고학년 아동의 식생활의 변화에 효과적인 것으로 나타 났으므로, 향후 초등학생 대상의 바람직한 식생활 함양을 위한 교육에 활용 가능한 것으로 보인다. 본 연구를 바탕으로 학습자의 특성과 지역의 특색을 고려한 다양한 맞춤형 식생활교육 프로그램의 활발한 개발과 적용을 통하여 아동의 발달과 삶의 질 향상에 기여하기를 기대한다.
        4,000원
        17.
        2014.06 구독 인증기관·개인회원 무료
        Trap-neuter-return (TNR), also known as trap-test-vaccinate-alter-release (TTVAR), is a method of humanely trapping unaltered feral cats, spaying or neutering them, and returning them to the location where they were collected. TNR is promoted by the some regional province governments as a humane and more effective alternative to euthanasia for managing and reducing feral cat populations. We are aimed to conduct the survey research to evaluate the recognition of status about TNR. We deals with the findings obtained from extensive interviews with a representative sample of 301 persons. The objectives of interviews included 20~50 year-old ages lived in Incheon, Goyang, Seosan, Iksan and Nonsan city. Questions focused on how people were recognized the need and policies of TNR. Questionnaire and technical data are analysed and summarized. As the results of the survey research, the objectives of interviews had poorly understood about the policies of TNR. Conclusionally, the promotions of TNR policies were need. The development of TNR policies were desirable for the establishment of animal welfare.
        18.
        2014.06 구독 인증기관 무료, 개인회원 유료
        This paper is derived from a survey research project investigating consumer attitudes towards organic food as the farm animal welfare. Presents focus group results on consumer perceptions, attitudes and recognition about farm animal welfare. We are aimed to conduct the survey research to evaluate the consumer's perception and demands of the farm animal welfare. We deals with the findings obtained from extensive interviews with a representative samples. The objectives of interviews included 20~60 year-old ages lived in Yongin, Anyang, Gunpo, Ansan, Seosan, Dangjin, Iksan and Jeonju city. Questions focused on how people were recognized the need and policies of farm animal welfare. Questionnaire and technical data are analysed and summarized. As the results of the survey research, the objectives of interviews had poorly understood about the policies of farm animal welfare. Conclusionally, the promotions of farm animal welfare policies were need. The development of farm animal welfare policies were desirable for the establishment of animal welfare.
        4,500원
        19.
        2014.06 구독 인증기관 무료, 개인회원 유료
        Registration and identification of companion dos in urban areas is important for the wellbeing of the animals themselves, owner's piece of mind, and to allow city to plan for future community needs. Recently, in Korea, all dogs in urban areas must be registered at the regional city offices. Owners are encouraged to implant microchips in their cats and dogs regardless of age as it ensures these pets can be quickly reunited with the owners after separation. We are aimed to conduct the survey research to evaluate the perception of companion dog's owners on the animal registration policy. We deals with the findings obtained from extensive interviews with a representative samples. The objectives of interviews included 300 owners in Iksan city. Questions focused on how people were recognized the need and policies of animal registration. Questionnaire and technical data are analysed and summarized. As the results of the survey research, the objectives of interviews had well understood about the policies of animal registration. Conclusionally, the promotions of animal registration policies were need. The development of fanimal registration policies were desirable for the establishment of companion animal welfare.
        4,000원
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