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        검색결과 982

        21.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 후박나무 용기묘를 대상으로 전광, 35%, 55%, 75% 차광수준에 따른 생장 특성 및 생리적 반응을 알아보고자 실시하였다. 후박나무 묘목은 차광 시 상대적으로 지상부의 생장특성을 보여주는 지표들이 높은 경향을 보였으며, 전광에서는 뿌리와 관련된 지표인 뿌리건중비, 뿌리생장에 서 유의적으로 높은 경향을 보였다. 또한, 전광에서의 낮은 광보상점과 높은 순양자수율은 이미 후박나무가 내음성을 가지고 있고, 광이 부족한 환경에 노출된 차광처리구들에서 암호흡량의 감소, PIABS 및 SFIABS의 증가로 광합성 기구의 활력을 효율적으로 증가시키는 것을 알 수 있다. 한편, 전광은 지상부 비율의 증가, 낮은 T/R율과 가장 높은 순광합성속도를 보여 광합성으로 합성되는 탄수화물이 지상부 뿐만 아니라 지하부의 생장 역시 증가시킨 것을 알 수 있는 결과였다. 따라서 후박나무 용기묘는 전광조건에서 생장 및 생리적 특성이 가장 양호한 경향을 보였다.
        4,200원
        22.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this work, we deal with the feasibility of structural topology optimization for beam designs using retrofits that optimally allocates the reinforcement to the web under the condition that designers set bolt regions for H-beams of different dimensions. Mean compliance or minimal strain energy is considered for the optimization. Volume fraction is given to the design space to assign appropriate steel material quantities. The purpose of this study is to evaluate optimal shapes of stiffeners with the maximum rigidity that improves the axial and shear performance of the H-beam and to satisfy a given safety design standard of H-beam and stiffeners in case arbitrary load effect and resistances. Finally, the effectiveness of stiffness-based topology optimization on stiffeners is verified with several practical applicable examples.
        4,000원
        23.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, a numerical analysis was performed as steady-state analysis to investigate the effect of interference between the propellers of the hexa-copter. As the distance increases, there is little change in thrust, but when a propeller close to the reference propeller rotates, it was confirmed that the thrust decreased due to the interference effect. Unsteady state analysis was performed to confirm the influence of the hexa-copter fuselage. If there is a fuselage, the thrust was predicted to increase by about 4.97% due to the ground effect. If the design parameters are established considering the effect of the fuselage of the hexa-copter, it is expected to be used for basic design and application design in the future.
        4,000원
        24.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper analyzed the price stabilization before and after the fisheries outlook project for seaweed, flatfish, and abalone. First, the stabilization effect was analyzed through the price variation coefficient before and after the observation project. In terms of the variation coefficient, there was no effect that the price was stabilized through the seaweed outlook project. However, it can be seen that flatfish and abalone have a price-stabilizing effect. Second, as a result of analyzing the price stabilization effect through the improved ARMA-T-GARCH model, it was confirmed that seaweed was not statistically significant while flatfish and abalone had a price stabilization effect by statistically significantly reducing volatility of real prices after the introduction of the fisheries outlook project. Third, as a result of analyzing the factors affecting price stability, it was found that the price of seaweed was stabilized after the WTO, but the Japanese earthquake expanded the price volatility. In the case of flatfish, it was analyzed that the price stabilized after the WTO and the Great Japanese Earthquake. Finally, the price of abalone has stabilized since the WTO and the Great Japanese Earthquake.
        4,300원
        25.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        작물 생육 진단에 있어서 군락 엽면적과 군락 피복은 주한 요소 이다. 최근에는 이러한 측정을 디지털 카메라를 활용하여 RGB 식생지수로 작물 생육을 측정하고 있다. 본 연구는 밀 재배 기간 카메라의 노출 값을 다르게 설정하여 RGB 컬러 식생 지수와 군락 엽면적지수 및 군락피복에 대해 평가하였다. 군락 엽면적, 군락 피복 및 디지털 영상 측정은 출수 16일전부터 출수 후 25일까지 하였다. 일출 후 30분 이내에 촬영하였다. 노출 값은 셔터 속도를3 수준(1/60s, 1/340s, 1/640s)으로 하였다. RGB 컬러 식생지수 분석은 파이썬으로 하였다. 실제 군락 엽면적과 군락 피복간에는 정의 상관관계(r2 =0.94)를 보였다. 군락 피복 이미지의 ExG, GLI, NGRDI, ExG-ExR, MExG, TGI, MNGRD 및 MExG-CIVE는 군락 엽면적 지수와 및 군락 피복과는 정의 상관관계를 보였다. 그러나 CIVE와 ExR은 부의 상관관계를 보였다. 본 연구 결과 1/640s 가 1/60s와 1/320s에 비하여 노출이 높게 설정된 것으로 보였다. 또한, 토양과 녹색 영역을 분리하는데 있어서 너무 어린 시기 보다는 출수 전이 가장 잘 분리되었다. 따라서 야외에서의 다양한 광 조건에서는 과도한 노출보다는 광 간섭을 줄이는 기술과 함께 작물의 생육 시기와 기상환경을 고려하여 노출 값이 설정되어야 할 것이다.
        4,500원
        29.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the noise reduction effect of the steam vent silencer was investigated by performing a transient flow analysis applying the Loss Model, a porous flow analysis model, and calculating the noise intensity from the pressure fluctuation according to the time change. As a result of flow analysis, it was confirmed that the noise intensity decreased as the number of diffusers and the number of splitters made of foamed aluminum increased. In the case of three-stage diffusers, the noise intensity decreased by up to 33.4 dB when six foamed aluminum with a thickness of 150mm were installed.
        4,000원
        31.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : Currently, the domestic construction industry is dominated by large-scale projects such as roads, ports, airports, and buildings. Construction on such projects is generally conducted simultaneously, but the process and quality management are led by a small number of responsible managers. In the case of road pavements, owing to rapid industrial development, economic growth, and the expansion of social overhead capital investment in the road construction industry, highways and general national roads have been constructed on a large scale. Therefore, this study aimed to improve and develop domestic concrete production and construction quality management by improving the reliability and transparency of production quality management and simplifying business processes. This was accomplished through the development of an Internet of Things (IoT)-based cement quality management system capable of automated design and build (D/B) construction and real-time monitoring. METHODS : The "IQ" system is a quality management system for enabling real-time monitoring of D/B quality at the time of concrete production and according to the designated age by utilizing quality test equipment developed with an LTE-Bluetooth function. It is possible to immediately identify and respond to quality problems through real-time monitoring, secure a reliable quality D/B because the quality test results cannot be arbitrarily manipulated, and to simplify the work process through the automatic D/B construction. In addition, improved quality control can be achieved through real-time information sharing and feedback system operations between contractors, managers, and personnel involved in construction. The quality control test items for developing the IQ system are the compression and flexural strengths, as these can be used to determine the design standard strength of pre-curing concretes (such as their slump and unit quantity) and the adequacy of the workability and durability, as well as the air volume to predict the durability, and the chloride content in the sections where reinforcement is used. CONCLUSIONS : This study identified difficulties and limitations in quality management according to the operation method in the domestic quality management systems, and in the real-time monitoring between managers and contractors. Thus, it was necessary to establish an improved systematic and reliable quality management system. The IQ system was developed to solve this problem.
        4,000원
        32.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The increasing heat wave warnings during the summer season in Korea have significant impacts on daily life and industry as a whole, especially in urban areas (such as areas with asphalt and sidewalk pavements). Heat waves directly affect urban heat island and heat dome phenomena. Various urban temperature reduction measures are being discussed to reduce urban heat islands and heat dome phenomena and to improve citizen safety against summer heat waves; suggestions include thermal packaging, rooftop greening, and expansion of vegetation areas. There is a lack of analysis on the methodology for increasing the road spraying effect during summer heat waves (e.g., there is no systematic engineering study on the effect from reducing the temperature of the road spraying during a heat wave in the city) and on the types of road pavements in the city. In addition, as the asphalt pavements of roadways and block pavements installed in sidewalks account for a considerable portion of all pavements, this study provides a more systematic and scientific approach and procedures for reducing temperatures through road spraying in the city by tracking the effects of heat waves. METHODS : In this preliminary experiment, four types of road pavement materials were selected as test specimens: asphalt test specimens (AP- 300 mm × 300 mm × 50 mm), concrete test specimens (CP-300 mm × 300 mm × 50 mm), impermeable blocks (IB-200 mm × 200 mm × 60 mm), and self-permeable blocks (PB-200 mm × 200 mm × 60 mm). As a test method to evaluate the size and duration of each spray effect package type, the surface temperature of each specimen was measured using thermal imaging cameras every 20 min after spraying at the maximum temperature point of each specimen, and the average surface temperature was analyzed based on the collected temperature data. In addition, to conduct a quantitative analysis of the effect of reducing the surface temperature of road pavements by road spraying in summer, field tests were conducted on asphalt roads and watertight blocks for sidewalks. RESULTS : As a result of the comparative analysis of the spray effect under a 36 ℃ air temperature based on a heat wave warning, the surface temperatures were, from high to low, the asphalt (68.8 ℃), concrete (59.1 ℃), impermeable block (57.3 ℃), and permeable block (58.7 ℃). The asphalt pavement had the greatest effect on the heat island and heat dome phenomena. From measuring the temperature reduction effect and sustainability of each type of road pavement, the surface temperature reduction effects were ranked in the following order: water-permeable block (Δ18.0 ℃), asphalt test piece (Δ17.5 ℃), concrete test piece (Δ12.2 ℃), and water-permeable block (over 240 min). In the report pitching block, the average road surface temperature reduction between the pore recovery and treatment was expected to continue to decrease by approximately -4.3 ℃ on the day of work and approximately -2.4 ℃ on the next day. The expected effect of the temperature reduction owing to simple spraying on the surface of the pore block was evaluated to be limited to the day. CONCLUSIONS : In the road spray effect analysis conducted on the common asphalt road, there was a slight difference in the initial temperature reduction size as the test specimen was measured, but the surface temperature difference between the non-spray section and spray section tended to be approximately Δ3°C after 140 minutes of spraying. Therefore, it was determined that the asphalt pavement temperature reduction plan through road spraying in urban areas in summer would be the most effective if it was repeated twice or more in an hour (between 13:00 and 14:00) on the day of the heat wave.
        4,000원
        33.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, to improve the optical quality of aspherical plastic lenses for mobile use, the optimal molding conditions that can minimize the phase difference are derived using injection molding simulation, design of experiments, and machine learning. First, factors affecting the phase difference were derived using the design of the experiment method, and a data set was created using the derived factors, followed by the machine learning process. After predicting the model trained using the generated training data as test data and verifying it with the performance evaluation index, the model with the best predictive performance was the random forest model. Therefore, to derive the optimal molding conditions, random forests were used to predict 10,000 random pieces of data. As a result of applying the derived optimal molding conditions to the injection molding simulation, the phase difference of the lens could be reduced by 8.2%.
        4,000원
        34.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, the medical industry’s use of biomaterial has taken an important place. A biomaterial is a semi-permanent material that can be used instead of a specific part of the body when there is a disability. Among them, Nitinol alloy has used in the human body, the material surface quality is very important, and research on processing methods is important to improve the surface quality. Therefore, in this study, a study was conducted to obtain high-quality surface quality using the MR polishing process. As a result, high-quality surface roughness was obtained at a wheel rotation speed of 400rpm(Ra=3.5nm).
        4,000원
        35.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research was conducted for dewatered sludge cake of industrial wastewater treatment, i.e., as the object of inorganic sludge discharged especially in iron & steel manufacturing shop which used Air drying system to reduce water content. That drying system's single-type cyclone separator was confirmed to have significantly lower separation efficiency on the conditions 20μm and below of particular size through computational fluid dynamics(CFD) analysis. However, we found out the primarily advanced value of separation efficiency on dual-type directly connected. Regarding separation efficiency on size of 10μm, the efficiency of a single-type was presented at 51.91%. On the other side, the efficiency of the dual-type was 97.88%. This advanced effect of the dual cyclone separator was checked at a demo facility of air drying equipment designed by 340m3/min of airflow on site.
        4,000원
        36.
        2022.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        선박입출항법은 그 공간적 적용범위를 무역항의 수상구역 등으로 한정하고 있다. 위 법률의 엄격한 문리해석상 무역항의 수상구역 등에서 제외된 수역에 는 해사안전법 내지 1972년 국제해상충돌예방규칙의 관련 항법규정들이 적용 될 것이지만, 해사안전법과 국제규칙의 입법취지를 비추어보면 연안항만에 위 법률과 규칙을 직접 적용하는 것은 적절하지 않다. 선박입출항법의 적용범위인 무역항의 수상구역 밖의 수역시설을 해양수산부장관이 관리권을 가진 국가관 리무역항에 한정하고 있는 항만법의 관련 규정은 입법론적으로 문제가 있다.그렇다면 비록 현행 법령의 해석으로는 지방관리무역항에 대해 선박입출항법 을 직접 적용할 수 없더라도, 지방관리무역항에서의 해상교통에 관해서도 선박 입출항법의 규정을 직접적용 또는 유추적용하는 것이 타당하다. 또한 해상교통 환경이 유사한 항만법상 연안항 내지 어촌·어항법상 어항에도 선박입출항법이 규정하는 항법을 유추 적용할 필요가 있다. 연안항만에서의 항법규정에 관해, 다수의 해양안전심판 재결에서 심판원은 해사안전법과 국제규칙의 관련 규정 들을 적용함에 따른 문제점들을 해소하기 위한 방안으로, ‘선원의 상무규정’을 적용하고 있다. 그러나 이는 일반조항으로의 도피로서 적절하지 않다. 한편 광 의의 해상교통법에 포함되는 유·도선법과 낚시관리법 등에서는 유선 및 도선과 낚시어선의 운항규칙에 관해 별도의 규정을 두고 있다. 위 법률들에서 규정하 는 운항규칙들은 해사안전법의 적용대상이 아닌 내수면을 운항하는 선박을 그 대상으로 한다는 점에서, 해수면 등을 운항하는 선박에는 해사안전법과 선박입 출항법의 관련 규정이 적용된다. 그러나 해사안전법의 항법 관련 규정은 연안 항만에 직접 적용하기에 적합하지 않고, 선박입출항법은 그 적용범위가 무역항 의 수상구역 등에 한정되어 있다는 점에서 낚시어선 등이 주로 입출항하는 연 안항 내지 어항 등에서의 항법 규정의 실효성이 떨어지는 문제가 있다. 그런데 유·도선법 및 낚시어선법에서 규정하는 운항규칙의 주요 내용은 선박입출항법 등의 실정법규에서 규정하는 항법규정과 그 괘를 같이한다는 점을 감안하면, 입법론으로서 유선 및 도선, 낚시어선 등에 적용되는 운항규칙을 해수면을 운 항하는 선박에도 확대할 필요가 있다.
        6,100원
        37.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This thesis relates to developing an index drilling automation system that quickly and efficiently processes a hole in a product by a rotating robot arm and transfer devices. Static structural analysis was performed using the ANSYS Mechanical program to evaluate the structural stability of the system. According to the research, the equivalent stress value is low overall, and the minimum safety factor is 4.42, so it seems structurally safe. This system will significantly help improve productivity through unmanned work as it can control and set the drill and index simultaneously on the control panel in conjunction with the training.
        4,000원
        38.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        천수만과 태안해역의 제한영양염을 평가하기 위해 장기자료 분석과 생물검정실험을 진행하였다. 우선 잠재적인 제한영양염을 평가하기 위해 국가수질측정망에서 제공되는 2004~2016년 동안의 장기 영양염 자료를 이용하였다. 장기자료의 DIN/DIP를 분석한 결과 대 부분 16이하로 N 제한이 우세하였지만 N, P, Si의 농도비를 이용한 분석에서는 하계와 추계에는 N 제한이 우세하였고, 동계와 춘계에는 해역에 따라 일부 Si 제한을 보이거나 또는 제한이 나타나지 않았다. 생물검정실험 시 채집된 현장수의 영양염 분석결과, DIN/DIP는 3월 과 5월에 모든 정점에서 P 제한을 나타냈고, 7월과 10월에는 N 제한이 우세하였다. N, P, Si의 농도비를 이용한 분석에서 3월과 5월은 P와 Si 제한을 보이거나 제한영양염이 나타나지 않은 정점이 존재하였으나 7월과 10월에는 N 제한이 우세하였다. 실질적인 제한영양염을 평 가하기 위해 수행된 생물검정실험 결과 3월에는 특정 제한영양염이 나타나지 않았으나, 5월, 7월 10월에는 NH4 +와 NO3 -가 반응을 보임으 로서 이 시기에는 N이 식물플랑크톤 성장에 직접 관여하는 실질적인 제한영양염임을 확인하였다.
        4,000원
        39.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper is about structural, and vibration analysis for the development of Index chucks Structural and vibration analyses were performed using the ANSYS Mechanical program to evaluate the Index chuck's structural stability and vibration characteristics. As a analysis result, when the maximum load of 500N was applied to the Index chuck, the safety factors were 2.06, 2.09, and 2.60, respectively, when the thickness was 5mm, and the outer diameters were 70mm, 90mm, and 120mm, respectively. Structurally safe results were obtained. In addition, under load conditions of 300 N or less, structural safety was confirmed if the thickness is 3mm or more.
        4,000원
        40.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        생태복원은 생태계의 건강성과 지속성에 있어 생물다양성의 손실을 막을 수 있는 좋은 수단으로 인식되어 있으나 식물종 선정에 관한 환경, 생리·생태요인, 복원목표 설정 등 종합이고 객관적인 기준점이 없어 실행에 옮기는데 애로사 항이 있다. 이에 전문가 그룹의 의견을 종합하는 델파이 기법을 활용하여 생태복원용 식물종을 선정하는데 필요한 평가지표를 개발하였다. 생태복원 등의 전문가를 대상으로 2회에 걸쳐 38부의 설문조사를 시행하여, 복원 대상지를 내륙과 도서 지역으로 나눠 평가지표의 중요도와 우선순위를 분석했다. 중요도 분석 결과, ‘자생식물’이라는 평가지표 가 내륙과 도서 지역에서 모두 평균 4.9로 가장 높았다. 다음 ‘종자확보’, ‘증식’, 활착률’ 순으로 높았다. 내륙의 지표 우선순위는 ‘자생식물’, ‘출현빈도’, ‘활착율’, ‘분포범위’, ‘종자확보’로 도서 지역은 ‘자생식물’, ‘활착율’, ‘출현빈도’, ‘분포범위’, ‘내성’ 순으로 나타났다. 중요도와 우선순위 분석을 수행한 결과 ‘내륙의 중요도 평균값은 4.1, 우선순위 2.9로 도서지역은 중요도 평균값은 4.2, 우선순위 2.9로 기준을 설정하였다. 생태복원용 식물종 선정의 중요도와 우선순 위는 ‘자생식물’이 중요도와 우선순위가 가장 높은 것으로 나타났다. 다음은 ‘종자확보’, ‘활착율’, ‘지형’, ‘증식’, ‘내 성’, ‘토양조건’, ‘생육특성’, ‘천이초기’, ‘분포범위’, ‘출현빈도’, ‘발아율’이 중요도와 우선순위가 낮은 하위 그룹으로 분류되었다. 가장 낮은 지표는 ‘천이 최종단계’, ‘천이장기’, ‘천이중기’, ‘뿌리’, ‘번식’, ‘토양’, ‘성상’, ‘기술’, ‘경관’, ‘기후’, ‘발아율’로 구분되었다. 이에, 생태복원용 식물종 선정을 위해 객관적 검증을 통한 생태복원용 자생식물 종 선정을 위한 평가지표로 복원사업에 활용되기를 기대한다.
        4,200원
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