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        검색결과 8,361

        61.
        2023.12 구독 인증기관 무료, 개인회원 유료
        Truck no-show behavior has posed significant disruptions to the planning and execution of port operations. By delving into the key factors that contribute to truck appointment no-shows and proactively predicting such behavior, it becomes possible to make preemptive adjustments to port operation plans, thereby enhancing overall operational efficiency. Considering the data imbalance and the impact of accuracy for each decision tree on the performance of the random forest model, a model based on the Borderline Synthetic Minority Over-Sampling Technique and Weighted Random Forest (BSMOTE-WRF) is proposed to predict truck appointment no-shows and explore the relationship between truck appointment no-shows and factors such as weather conditions, appointment time slot, the number of truck appointments, and traffic conditions. In order to illustrate the effectiveness of the proposed model, the experiments were conducted with the available dataset from the Tianjin Port Second Container Terminal. It is demonstrated that the prediction accuracy of BSMOTE-WRF model is improved by 4%-5% compared with logistic regression, random forest, and support vector machines. Importance ranking of factors affecting truck no-show indicate that (1) The number of truck appointments during specific time slots have the highest impact on truck no-show behavior, and the congestion coefficient has the secondhighest impact on truck no-show behavior and its influence is also significant; (2) Compared to the number of truck appointments and congestion coefficient, the impact of severe weather on truck no-show behavior is relatively low, but it still has some influence; (3) Although the impact of appointment time slots is lower than other influencing factors, the influence of specific time slots on truck no-show behavior should not be overlooked. The BSMOTE-WRF model effectively analyzes the influencing factors and predicts truck no-show behavior in appointment-based systems.
        4,800원
        62.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we have developed a movable defect detection system based on a vision module with machine-learning algorithm for distinguishing product quality. Machine-learning model determined the results in good or no good through images acquired from the vision module consisting of a camera, processor unit, and lighting. To ensure versatility for use in a variety of settings, we have integrated a robot arm and cart for the movable defect detection system, and the robot arm that adjusts the focus length is made to be able to rotate in all directions. The type of defect was divided into eccentricity defect and printing defect. As a result, it was confirmed that classification accuracy showed 0.9901 in our developed device.
        4,000원
        63.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study developed an IoT-based agricultural well control system and demonstrated it through a control system in the current state of domestic open-field smart farms where systematic management is insufficient due to the difficulty of collecting accurate data such as agricultural water intake and usage. As a result, it was possible to derive the optimal control system test results according to the watering conditions for each schedule by conducting automatic control focusing on periods when there is no precipitation. This means that irrigation can be carried out smoothly during the time when irrigation is needed to improve crop quality and secure farm income, and as a result, it is possible to systematically manage and operate among demonstration farms connected to irrigation, resulting in a shortage of agricultural water and a resolution of supply imbalances.
        4,000원
        64.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For motor controller designers, building a simulation environment is not a difficult process. After verifying the controller by simulation, it is common to select 20kHz for the current control loop, 1kHz for the speed loop, and 100Hz for the position loop when implementing the actual HW embedded system. This is because maximized cycles (20kHz) for each control loop are unnecessary in control theory and are a waste of cost and HW resources. However, in a simulation environment, each loop will often have the same control cycle (20kHz maximum). This is because we think it is unnecessary to reflect this part in the simulation. In this paper, it is shown that the difference in the sampling time of each control loop makes a big difference in the simulation result, and as a solution, it is proposed to apply LPF to the position loop output stage. In the process, the reasons for the differences were analyzed, and the effect of LPF, the reason for application, and the feasibility of implementation were proved by actual software coding.
        4,000원
        65.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        An in-wheel motor is a system in which a drive motor is mounted inside a wheel along with a braking device, and the motor inside the wheel directly drives the wheel. An SR motor drive in replace of the conventional PM motor drive for in-wheel motor system has been proposed and analyzed. Two different types of converters were selected and their feasibility in terms of different current control schemes was analyzed and validated through dynamic simulation using PSIM software.
        4,000원
        66.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Air blower has been widely used in many industrial fields such as wind tunnel and large ventilation systems. Its performance is affected by operating conditions and system geometry of inpeller and duct, and these design parameter optimization is essential for the effective development. CFD analysis is carried out to investigate the air flow field characteristics with outlet total pressure in a blower system. Intake air into the impeller blade through the inlet is compressed, and then gradually discharged from the outlet with ascending total pressure, and predicted results are compared with test data. Especially this overall pressure difference in the blower system severely depends on the flow rate. These results are expected to be used as applicable design data for blower performance improvement.
        4,000원
        67.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, a condensate drain valve was newly installed in the steam inlet pipe line of the soot blower to reduce the amount of condensate contained in the steam for the soot blower. When the economizer is inactive, the condensate drain valve on the soot blower steam inlet pipe line is always opened to drain the condensate. It is intended to reduce environmental pollution and improve economizer performance by reducing the water hammer that inevitably occurs in facilities using steam, and reducing the amount of condensate water generated during the shutdown of the soot blower and the release of soot containing condensate water into the atmosphere when removing soot.
        4,000원
        68.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, a tidal power conversion system (PCS) using seawater level differences was presented.. To verify the presented PCS, an actual lab-scale tidal power generation system was constructed. The operation of the lab-scale PCS was first modeled mathematically and was analyzed through dynamic simulation and experimental tests.
        4,000원
        69.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        항만 내 선박과 부두의 사고를 예방하기 위하여 통항 및 접안 안전성 평가를 통하여 안전한 부두가 건설되어 관리하고 있으나, 선 박의 접안 및 계류 과정에서 선박이 부두에 충돌하거나 로프로 인한 인명사고의 발생 등 예측할 수 없는 사고들이 종종 발생한다. 자동계류장 치는 선박의 신속하고 안전한 계류를 위한 자동화된 시스템으로 로봇 매니퓰레이터와 흡착 패드로 구성된 탈/부착 메커니즘을 가지고 있다. 본 논문은 자동계류장치의 흡착 패드의 위치 및 속도제어에 필요한 선체와의 변위 및 속도 측정 시스템을 다룬다. 자동계류장치에 적합한 측 정 시스템을 설계하기 위하여, 본 논문은 우선 센서의 성능 및 실외 환경적 특성 분석을 수행한다. 다음으로 이러한 분석 결과를 토대로 실외 부두환경에서 설치되는 자동계류장치에 적합한 변위 및 속도 측정시스템의 구성 및 설계 방법에 대해 기술한다. 또한 센서의 측정상태 감지 및 속도 추정을 위한 알고리즘을 제시한다. 제안된 방법은 다양한 속도 구간에서의 변위 및 속도 측정 실험을 통해 그 유용성을 검증한다.
        4,300원
        70.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 역사적 제도주의를 활용해 박정희 정부의 국회의원 선거제 도를 생성 과정, 지속 과정, 조정 과정, 변화 과정으로 검토하고자 하였 으며, 그 결과는 다음과 같다. 첫째, 생성 과정이다. 권력장악을 위한 정 당추천제, 소선거구제, 제1당에 유리한 전국구 배분 원칙이 적용된 국회 의원선거법은 집권당에게 득표율 대비 의석률에 유리하였다. 둘째, 지속 과정이다. 제1당에 유리한 국회의원선거법이 유지되면서 집권당의 일당 우위정당체제는 더욱 강화되었다. 셋째, 조정 과정이다. 기존 선거제도에 서 의석수의 확대, 등록기간의 축소, 배분 제한조건의 강화 등 변화가 있 었고, 집권 세력에 대한 국민의 저항으로 제1야당은 집권당을 견제할 수 있게 되었다. 넷째, 변화 과정이다. 집권위기에 직면한 집권세력은 중선 거구제를 도입하여 지역선거구에서 국회의 과반수 의석을 확보하였다. 박정희 정부에서 제1당은 이득비와 보너스율에서 이득을, 제2당은 제9대 국회의원선거를 제외하면 이득비와 보너스율에서 손해를 보았다. 박정희 정부의 국회의원 선거제도는 제1당에 유리한 양당 체제를 강화하였으나 집권세력이 권력창출, 권력유지, 권력연장, 영구집권을 위해 국회의원 선 거제도를 도구로 활용했다는 비판에 직면하였다.
        7,700원
        71.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aimed to develop a solid self-nanoemulsifying drug delivery system (solid-SNEDDS) to enhance the formulation of ketoconazole (KTZ), a BCS Class II drug with poor solubility. Ketoconazole, which is insoluble above pH 3, requires solubilization for effective delivery. This SNEDDS comprises oil, surfactant, and co-surfactant, which spontaneously emulsify in the gastrointestinal tract environment to form nanoemulsions with droplet sizes less than 100 nm. The optimal SNE-vehicle composition of oleic acid, TPGS, and PEG 400 at a 10:80:10 weight ratio was determined based on the smallest droplet size achieved. This composition was used to prepare liquid SNEDDS containing ketoconazole. The droplet size and polydispersity index (PDI) of the resulting liquid SNEDDS were analyzed. Subsequently, solid-SNEDDS was fabricated using a spray-drying method with solidifying carriers such as silicon dioxide, crospovidone, and magnesium alumetasilicate. The physicochemical properties of the solid-SNEDDS were characterized by scanning electron microscopy and powder X-ray diffraction, and its solubility, droplet size, and PDI were evaluated. In particular, the solid-SNEDDS containing ketoconazole and crospovidone in a 2:1 weight ratio exhibited significantly enhanced solubility, highlighting its potential for improved medication adherence and dissolution rates.
        4,000원
        72.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Many changes in the scale and structure of the Korean rice cropping system have been made over the past few decades. Still, insufficient research has been conducted on the sustainability of this system. This study analyzed changes in the Korean rice cropping system’s sustainability from a system ecology perspective using an emergy approach. For this purpose, an emergy table was created for the Korean rice cropping system in 2011, 2016, and 202, and an emergy-based indicator analysis was performed. The emergy analysis showed that the total emergy input to the rice cropping system decreased from 10,744E+18 sej year-1 to 8,342E+18 sej year-1 due to decreases in paddy field areas from 2011 to 2021, and the proportion of renewable resources decreased by 1.4%. The emergy input per area (ha) was found to have decreased from 13.13E+15 sej ha-1 year-1 in 2011 to 11.89E+15 sej ha-1 year-1 in 2021, and the leading cause was a decrease in nitrogen fertilizer usage and working hours. The amount of emergy used to grow 1 g of rice stayed the same between 2016 and 2021 (specific emergy: 13.3E+09 sej g-1), but the sustainability of the rice cropping system (emergy sustainability index, ESI) continued to decrease (2011: 0.107, 2016: 0.088, and 2021: 0.086). This study provides quantitative information on the emergy input structure and characteristics of Korean rice cropping systems. The results of this study can be used as a valuable reference in establishing measures to improve the ecological sustainability of the Korean rice cropping system.
        4,800원
        73.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Risk assessment on Jeju Special Self-Governing Province(JSSGP)’s water supply facilities and establishment of adaptation measures for climate crisis factors were implemented. JSSGP’s vulnerability to the climate crisis was high in the order of drought, heat wave, heavy rain and strong wind. As a drought adaptation measure, policies of water saving and revenue water ratio improvement were considered. As for the heat wave adaptation measure, the introduction of an advanced water treatment process was suggested in response to the increase of algae cell number which resulting in taste and odor problem. As for heavy rain adaptation measures, the installation and operation of automatic coagulant injection devices for water purification plants that take turbid surface water were proposed. As a measure to adapt to strong winds, stabilization of power supply such as installation of dual power line was proposed in preparation for power outages. It is expected that water facilities will be able to supply high-quality tap water to customers even under extreme climate conditions without interruption through risk assessment for climate crisis factors and active implementation of adaptation measures.
        4,000원
        74.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study is to develop an comprehensive validation methodology for autonomous mobility-on-demand system with level 4 automated driving system. METHODS : The proposed method includes the quantitative techniques for validating both automated driving system and center system using each optimal indicators. In addition, a novel method for validating the whole system applying multi-criteria decision methodology is suggested. RESULTS : The relative weights for the vehicle system was higher than the center systems. Moreover, the relative weights of failure rate for validating the vehicle system was the highest, in addition to, a relative weight for accuracy of dynamic routing algorithm within center system was the highest. CONCLUSIONS : The proposed methodology will be applicable to validate the autonomous mobility on demand system quantitatively considering the relative weights for each systems.
        4,200원
        75.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study is to analyze the reduction effect on road pavement damage from the installation of weigh-in-motion systems used for overloaded vehicle enforcement, from the perspective of traffic assignment. METHODS : Fixed-demand multi-class traffic assignment was conducted by VISUM, a macroscopic traffic simulation software. We considered three vehicle classes and calculated the traffic load for each road link using the ESAL(Equivalent Single Wheel Load) factor, as proposed by ASHTTO(American Association of State Highway and Transportation Officials). We set up scenarios with weigh-in-motion installations in certain sections and observed how the traffic load changed before and after the installation of weigh-in-motion for each scenario. RESULTS : Three main trends were observed. Firstly, at points where weigh-in-motion systems were installed, traffic load significantly decreased even with the influx of cars and trucks following the restriction of overloaded trucks, highlighting the significant influence of overweight vehicles on the traffic load. Secondly, even when overweight vehicles detoured, there was no significant change in the overall network's traffic load. Lastly, the detour of overweight vehicles led to an increase in the total driving distance and time for all vehicles. CONCLUSIONS : Installing weigh-in-motion systems in sections with a lower structure number, which indicates thinner road pavement, can prevent damage in those specific areas without affecting the entire road network.
        4,000원
        76.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As a means to activate eco pastoral system in alpine grassland, the government can consider public pastures, which are currently unused, to scale them up into public ranches. Depending on ownership and operation, four management models proposed as follows: 1) Government-Owned and Operated with Balanced Profit and Loss 2) Government-Owned and Operated with Revenue Generation 3) Government-Owned but Privately Operated by Outsourced to Professional Manager 4) Full Privatization (Ownership and Operation by Private Individuals). The study outlined above proposes four management models for the activation of eco pastoral system in alpine grassland. It also suggests methods for the selection and performance evaluation of manager to establish a profitable structure. Additionally, the research provides management methods for the conservation of grazing ecology in pastoral ecosystems. Particularly, the adaptation of tools commonly used in South Korean business sector for the selection and performance evaluation of manager within the system of the proposed management models. This aspect is deemed valuable as it aligns these tools with the specific characteristics of eco pastoral system in alpine grassland, contributing not only to the effective implementation of the models but also to the enhancement of the revenue structure.
        4,000원
        77.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The wedge-type anchorage system requires a complex analysis of not only the tensile stress of the CFRP plate, but also the compressive stress and shear stress generated by the wedge action. The purpose of this study is to find a composite material failure theory that is suitable for analyzing the behavior of wedge-type anchorage system among various failure theories. METHODS : In this study, numerical analysis of various composite material failure theories was performed to analyze the anchorage strength and failure mode of the wedge-type anchorage system according to each failure theory, and compared with actual test results to determine the composite material failure theory most suitable for analyzing the behavior of a wedge-type anchorage system. RESULTS : Since the Maximum Stress failure theory shows similar results to the actual test in terms of failure mode and anchorage strength, there is no significant problem in applying it to the wedge-type anchorage system. However, it is judged to be difficult to apply under property conditions where interactions between stresses are highlighted. The Tsai-Hill and Tsai-Wu failure theories are considered unsuitable for application to wedge-type anchorage systems because the wedge angle conditions at which the most advantageous anchorage strength occurs are significantly different from other theories and the fracture type cannot be predicted. The Hashin-Rotem failure theory is considered to be the most appropriate to apply as a failure theory for the wedge-shaped anchorage system because the anchorage strength was slightly lower than the actual test results, but there was no significant difference, and the failure mode was consistent with the test results. The Hashin failure theory is judged to be unsuitable for application as a failure theory for the wedge-type anchorage system because the anchorage strength and failure mode were interpreted differently from the actual test results. CONCLUSIONS : The Hashin-Rotem failure theory was presented as the composite material failure theory most suitable for analyzing the behavior of wedge-type anchorage system.
        4,000원
        78.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 생리적, 환경적 변화에 따른 명태 Gadus chalcogrammus 피부계의 변화 연구를 위 한 기초 연구로서 피부계의 구조, 구성 세포 종류 및 조직화학적 특징을 기재하였다. 측선은 전반부가 완만한 곡선형이었으며, 중반부터 후반부까지는 직선으로 나타났다. 피부는 상피층과 진피층으로 구성되며, 상피층은 다층으로 상피세포, 점액세포, 곤봉세포로 이루어져 있다. 상피 세포는 표면층의 편평형 세포, 중간층의 입방형 세포, 기저층의 원주형 세포로 구성된다. 상피 층의 두께는 122.9 μm, 체장에 대한 상피층의 두께 비율은 0.03%였다. 단세포선인 점액세포와 곤봉세포는 주로 상피층의 표면층과 중간층에 분포하며, 점액세포는 산성 당단백질의 점액물 질을 함유하고 있었다. 상피층에서 점액세포와 곤봉세포의 분포비율은 각각 21.3 (± 7.0.)%와 4.0 (± 1.0)%였다. 진피층은 치밀결합조직으로 주로 콜라겐 섬유로 구성되며, 섬유세포, 혈관, 색소포, 비늘이 관찰되었다.
        4,000원
        79.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, due to the expansion of the logistics industry, demand for logistics automation equipment is increasing. The modern logistics industry is a high-tech industry that combines various technologies. In general, as various technologies are grafted, the complexity of the system increases, and the occurrence rate of defects and failures also increases. As such, it is time for a predictive maintenance model specialized for logistics automation equipment. In this paper, in order to secure the operational safety and reliability of the parcel loading system, a predictive maintenance platform was implemented based on the Naive Bayes-LSTM(Long Short Term Memory) model. The predictive maintenance platform presented in this paper works by collecting data and receiving data based on a RabbitMQ, loading data in an InMemory method using a Redis, and managing snapshot DB in real time. Also, in this paper, as a verification of the Naive Bayes-LSTM predictive maintenance platform, the function of measuring the time for data collection/storage/processing and determining outliers/normal values was confirmed. The predictive maintenance platform can contribute to securing reliability and safety by identifying potential failures and defects that may occur in the operation of the parcel loading system in the future.
        4,200원
        80.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
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