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        검색결과 5,012

        603.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to improve the noise measurement method of noise sources and the corresponding noise reduction measures during each manufacturing process closest to the workers in the large and hige power machine. To this end, the noise generated in the large and high power machine was measured and analyzed, and the frequency characteristics of noise sources and the causes of noise were identified. The noise map was used to predict the noise reduction effect. Moreover, it is expected that this will ultimately contribute to the reduction of human risks caused by the noise of the large and high power machine.
        4,000원
        604.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        식물사회네트워크란 식물사회를 이해하기 위한 기존의 식물사회학적 방법과 사회과학에서 최근에 주목받고 있는 사회연결 망 분석 방법을 접목하여 식물사회연결망을 시각화하고 분석하는 것을 말한다. 구축 및 분석 과정은 조사구 설정 및 출현 수종 조사, 종간결합분석, 소시오그램 작성, 네트워크 구조 및 중심성 분석 순으로 진행된다. 식물사회네트워크를 구축하기 위해 본 연구는 해안식생과 내륙식생을 동시에 볼 수 있는 부산광역시를 중심으로 다양한 상관우점식생이 포함되도록 708개 조사구를 설치하여 출현 수종을 조사하였다. 조사 결과, 출현한 수종은 모두 195종이었으며, 상록수 42종, 낙엽수 151종, 반상록수 2종으로 나탔으며, 전체 출현수종을 중심으로 종간결합분석을 실시하였다. 종간결합 분석 결과, 친화종수는 사스레피 나무(47종), 마삭줄(46종), 감태나무(44종), 팥배나무(44종), 광나무(41종) 순으로 나타났으며, 이를 바탕으로 gephi 0.9.2. program을 활용하여 소시오그램을 작성하였다. 작성된 소시오그램은 해안에서 주로 출현하는 그룹과 그렇지 않은 그룹으로 나뉘어져 있어 부산광역시 산림식생의 지리적 분포특성을 반영하고 있었다. 네트워크 구조를 분석한 결과, 1,709개의 연결선 (link)이 나타났고, 한 수종과 종간결합을 갖는 종수의 평균은 약 17.5개였다. 밀도는 0.09, 지름은 5, 평균 경로거리는 2.268로 분석되었는데, 사회과학분야의 네트워크 특성과 정밀한 비교 분석을 위해 앞으로 다양한 식물사회네트워크 구축이 진행되어야 할 것으로 판단되었다. 부산광역시 식물사회네트워크에서는 사스레피나무, 감태나무, 광나무, 마삭줄 등이 중심성 이 높은 것으로 나타났다.
        4,300원
        605.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Several analytical measurement techniques have been developed over the years for ammonia (NH3). However, the field monitoring of NH3 still remains a significant challenge owing to the wide range of possible environmental conditions and NH3 concentration. In this regard, it is imperative to ensure the quality control of techniques to measure the NH3 emission levels reliably. A present study was conducted to compare the five analytical methods for the measurement of atmospheric NH3 via validation tests under laboratory and field conditions. The analytical instruments applied in the present study were based on wet chemistry, gas detection tube, electrochemical sensor, photoacoustic spectroscopy, and cavity ring-down spectroscopy. The reproducibility and linearity of all the analyzed methods were observed to be high with the relative standard deviation and coefficient of determination (R2) being 10% and > 0.9, respectively. In the case of wet chemistry and high NH3 concentration, the measured NH3 results were found to be close to the actual standard gas levels. Response times of electrochemical sensor showed faster from the instruments utilized more than one year and the high NH3 concentrations. In the field tests, NH3 concentration showed higher in the manure storage tank compared with the pig-pen. In both cases, the NH3 concentration levels measured by gas detection tube were found to be quite different from that of wet chemistry. It was proposed that such differences in NH3 concentration could arise due to the inherent instrumental characteristics and the variations in air velocity during sampling/measurement. The periodic instrumental maintenance, verification, replicate analyses, and suitable consideration of environmental factors should be considered for a more reliable measurement of NH3 concentration under real field conditions.
        4,300원
        606.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        2016년에 쌍별귀뚜라미는 식품의약품안전처 식품공전에 등록된 식품원료로 가장 큰 장점은 월동 없이 연중 대량 사육이 가능하다는 것과 60% 이상의 단백질 함량이다. 본 연구에서는 사육공간, 인건비 등의 문제로 인하여 귀뚜라미 사육이 불가능할 때를 대비하여 저장조건을 설정하 였으며, 산란율이 높은 산란처 선발과 알의 동종포식률을 조사하였다. 산란은 상토 산란처에서 가장 선호도가 높았으며(p < 0.05), 알의 동종포식 률을 보았을 때 10 L 당 종령 약충 62마리 이하, 1일 동안 산란을 받는 것이 가장 적합한 것으로 판단되었다(p < 0.05). 알의 저온 저장을 하였을 때는 28℃에서 10일간 보관 후 16℃에서 10일간 저온 저장했을 때 부화율이 가장 높았고, 저장을 하지 않았을 때와 비교하였을 때 12~14일 부 화를 연장할 수 있었다(p < 0.05). 쌍별귀뚜라미의 산란처, 산란 방법 및 알 저장조건을 설정함으로써 효율적인 생산방법을 제시하였다.
        4,000원
        607.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : In this paper, pedestrian-oriented time assured traffic operation (POTATO), adopted in Korea at a single crossing pedestrianoriented operating area, is explored and applied to a simulation experiment and test site to verify the operation efficiency. METHODS : Three candidate plans are presented as a method to operate pedestrian-oriented signal operations that can overcome the restrictions on signal controllers in Korea. The selected POTATO and TOD signal operations were compared and analyzed. The delay and pedestrian queues, present length, and number of times were used as comparative indices. RESULTS : Scenario-specific simulations confirmed that the delay, compared to TOD signal operation, was reduced by up to 5 s/ped depending on the vehicle traffic volume and the number of pedestrians. For the vehicle delay, the results increased up to 8.99 s/veh, depending on the traffic volume of the vehicles and pedestrians. As a result of the test site operation, POTATO operation improved by 5.12 s/ped (approximately 46.69% improvement) compared to TOD operation in the hours commuting to school and by 2.84 s/ped in the hours commuting from school (approximately 51.13% improvement). In case of vehicle delay, the delay increased by 2.35 s/veh (approximately 64.39%) in the hours commuting to school and 1.20 s/veh (approximately 21.11%) in the hours commuting from school compared to the TOD operation. CONCLUSIONS : Through simulations and test site pilot operation verifications, the effects of pedestrian delay improvement were more positive if POTATO proposed in this study was low in vehicle traffic.
        4,000원
        608.
        2020.06 KCI 등재 구독 인증기관·개인회원 무료
        대법원 2016. 10. 27. 선고 2014도16271 판결(대상판결)은 관세포탈죄를 처벌하기 위한 포탈세액을 산정하는 방법으로 관세법 제31조에서 제35조까지 보충적 과세가격 결정방법을 사용할 수 있다고 판시하였다. 반면 관세법에서는 관세법 제31조에 따른 ‘거래가격을 기초로 한 관세평가’가 과세가격 결정의 원칙임을 선언하고 있으며 이는 WTO 관세평가 협정을 따른 것이다. 대상판결의 위 판시는 실체적 진실의 발견을 목적으로 하고 죄형법정 주의의 원칙의 따라야 하는 형사소송에서 실제 거래가격에 따른 관세액 이 아닌 실제 거래가격에 가깝게 추정하는 것에 불과한 보충적 과세가격 결정방법으로 산정한 관세액으로 관세포탈죄의 구성요건인 포탈세액을 결정할 수 있는지 의문을 던진다. 본고는 먼저 조세포탈죄를 처벌하기 위해 포탈세액을 ‘추계(추정계산)’ 할 수 있다는 조세포탈죄에서의 논의를 대상판결에 적용하여, 예외적인 방법으로 포탈세액의 기준이 되는 과세가격을 추정할 수 있는지 검토하였다. 그리고 WTO 관세평가 협정의 원칙이 어떤 의미를 가지는지를 살펴보고, 이러한 원칙과 대상판결의 관계를 ‘실체적 진실 발견’의 관점에서 분석했다. 그리고 앞선 논의를 바탕으로 대상판결이 형법의 명확성의 원칙과 형사소송법의 증명책임의 원칙을 위반하지 않는지 검토하였다. 대상판결은 죄형법정주의 원칙과 WTO 관세평가 협정의 원칙에 부합하며, 관세포탈범에 대한 처벌의 필요성, 관세포탈범에 대한 형사소송에 서의 실체적 진실발견, 그리고 형사법의 원칙들이 적절히 균형을 이루어져 있다고 평가할 수 있다. 다만, 보충적 과세가격 결정방법을 적용함에 있어 명확성의 원칙이 한 걸음 양보해야 한다는 점은 아쉬움으로 남는다. 따라서 본고는 검사가 보충적 과세가격을 결정하는데 기초가 되는 사실이 정확하다는 점과 해당 방법이 실제 포탈세액을 최대한 근사하게 추정할 수 있는 객관적 방법이라는 점을 합리적으로 보여야 한다는 점을 제시하였다. 본고는 검사의 이러한 입증책임이 전제되어야 대상판결이 보충적 과세가격 결정방법을 통해 포탈세액을 특정할 수 있다고 판시한 것이 명확성의 원칙에 어긋나지 않음을 강조하였다.
        609.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study was performed to evaluate the short-term aging (SA) protocols of the normal hot-mix asphalt (HMA) mixture, to explore problems, and to suggest proper procedures based on fundamental principles of SA in terms of the SA temperature (T) and length of time (Lt) in existing specifications in several countries including Korea. METHODS : As the SA in our lab is a simulation of field SA, which is an inevitable procedure occurring naturally in the current field practice, major SA guidelines of foreign countries and Korea were reviewed to investigate problems that showed discrepancies with field practice. The aging quantity (Aq) model was introduced as a function of T and Lt, based on the correlation with absolute viscosity (AV) to estimate Aq by T and Lt. The normal SA (NSA) was suggested through an example procedure inducing binder aging level similar to the RTFOtreated binder AV or Aq. Based on the NSA Aq level, lower, proper, or higher SA conditions were discovered from the existing SA guidelines. RESULTS : As Aq has excellent correlation with AV, the proper T and Lt for NSA as an example was suggested based on the AV of RTFOtreated binder to induce an Aq range of 19,000-25,000 min.℃. It was found that there were several problems in the existing guidelines in USA and Korea. These included lower T, shorter or longer Lt, and air blowing or stirring the mix during SA, which were not matched with the practical condition of loaded HMA mixtures that were short-term aged under hot temperatures in trucks. CONCLUSIONS : It was concluded that there are several problems in the current SA guidelines, which do not provide proper HMA temperature to mixtures for proper (modal) length of time. Therefore, these guidelines should be reevaluated carefully and revised based on the fundamental field SA principle. The NSA condition should be suggested using proper HMA T and modal Lt for better simulation of field SA practice.
        4,200원
        610.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        IEC 60079-10-1 edition 2.0, the global standard for hazardous area classification, was newly revised in 2015. There are many differences compared to the previous edition 1.0 version, first released in 2008, so it has caused confusion in the industry. In case of edition 1.0, the hazardous area extent can be derived through the mathematical formula, but in case of edition 2.0, there was the problem that the exact hazardous area extent was not known because of the mathematical formula of the plot for applying the hazardous area extent was not presented. In this study, we converted the plot introduced in edition 2.0 to CAD format and derived the plot as the mathematical equations. Through this, we suggest the hazardous area extent formula of three states (heavy gas, diffusive, jet). As the IEC committee did not provide the mathematical formula of the hazardous area extent according to the release characteristic, it is impossible to apply the exact hazardous area extent. In this study, a mathematical approach was derived for the plot introduced in edition 2.0, which can reduce the confusion of the applying hazardous area extent.
        4,200원
        611.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, a study of prognosis and health management (PHM) was conducted to diagnose failure and predict the life of air craft engine parts using sensor data. PHM is a framework that provides individualized solutions for managing system health. This study predicted the remaining useful life (RUL) of aeroengine using degradation data collected by sensors provided by the IEEE 2008 PHM Conference Challenge. There are 218 engine sensor data that has initial wear and production deviations. It was difficult to determine the characteristics of the engine parts since the system and domain-specific information was not provided. Each engine has a different cycle, making it difficult to use time series models. Therefore, this analysis was performed using machine learning algorithms rather than statistical time series models. The machine learning algorithms used were a random forest, gradient boost tree analysis and XG boost. A sliding window was applied to develop RUL predictions. We compared model performance before and after applying the sliding window, and proposed a data preprocessing method to develop RUL predictions. The model was evaluated by R-square scores and root mean squares error (RMSE). It was shown that the XG boost model of the random split method using the sliding window preprocessing approach has the best predictive performance.
        4,000원
        612.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Anomaly detection of Machine Learning such as PCA anomaly detection and CNN image classification has been focused on cross-sectional data. In this paper, two approaches has been suggested to apply ML techniques for identifying the failure time of big time series data. PCA anomaly detection to identify time rows as normal or abnormal was suggested by converting subjects identification problem to time domain. CNN image classification was suggested to identify the failure time by re-structuring of time series data, which computed the correlation matrix of one minute data and converted to tiff image format. Also, LASSO, one of feature selection methods, was applied to select the most affecting variables which could identify the failure status. For the empirical study, time series data was collected in seconds from a power generator of 214 components for 25 minutes including 20 minutes before the failure time. The failure time was predicted and detected 9 minutes 17 seconds before the failure time by PCA anomaly detection, but was not detected by the combination of LASSO and PCA because the target variable was binary variable which was assigned on the base of the failure time. CNN image classification with the train data of 10 normal status image and 5 failure status images detected just one minute before.
        4,000원
        613.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        There are several methods of peak-shaving, which reduces grid power demand, electricity bought from electricity utility, through lowering “demand spike” during On-Peak period. An optimization method using linear programming is proposed, which can be used to perform peak-shaving of grid power demand for grid-connected PV+ system. Proposed peak shaving method is based on the forecast data for electricity load and photovoltaic power generation. Results from proposed method are compared with those from On-Off and Real Time methods which do not need forecast data. The results also compared to those from ideal case, an optimization method which use measured data for forecast data, that is, error-free forecast data. To see the effects of forecast error 36 error scenarios are developed, which consider error types of forecast, nMAE (normalizes Mean Absolute Error) for photovoltaic power forecast and MAPE (Mean Absolute Percentage Error) for load demand forecast. And the effects of forecast error are investigated including critical error scenarios which provide worse results compared to those of other scenarios. It is shown that proposed peak shaving method are much better than On-Off and Real Time methods under almost all the scenario of forecast error. And it is also shown that the results from our method are not so bad compared to the ideal case using error-free forecast.
        4,500원
        617.
        2020.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The aim of this study was to investigate the physicochemical characteristics of hand drip, Aeropress, espresso, Moka, Mukka, and Brikka coffee brews. Espresso showed higher antioxidant activity, total solids, caffeine, chlorogenic acid, total phenolic compounds, and trigonelline concentrations compared to the other coffee brews studied. In terms of extraction efficiency, Brikka and Mukka showed higher total solids, as well as caffeine and chlorogenic acid contents, whereas drip coffee brew showed higher trigonelline content than other coffee brews. Meanwhile, principle component analysis (PCA) was conducted based on the aroma profile by e-nose. Samples were gathered into distinct groups that represented their brewing methods. Despite the similarity in brewing principle between Moka and other high-temperature brewing methods (i.e., Mukka and Brikka), the location of Moka coffee brew was closer to that of espresso in PCA, which was consistent with the PCA result conducted by e-tongue.
        4,000원
        618.
        2020.05 구독 인증기관 무료, 개인회원 유료
        3,000원
        619.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to compare differences in the main food components of quinoa (Chenopodium quinoa Willd.) cultivated in Hongcheon after steaming, boiling, and roasting. Among the general components, crude protein, fat, and ash content were the highest in raw quinoa. Dry matter and carbohydrate content was the highest in steamed quinoa, while total dietary fiber content was highest in roasted quinoa. Total amino acid contents were the highest in boiled quinoa and lowest in steamed quinoa. Fatty acid content was highest in raw quinoa and lowest in boiled quinoa. The mineral (calcium, potassium, and phosphorus) and vitamin content was most enriched in raw quinoa, while iron, magnesium, zinc, and manganese were highest in boiled quinoa. For free sugars, the fructose and sucrose levels were highest in raw quinoa, while glucose level was highest in roasted quinoa. The water-soluble vitamin and free sugar contents were lowest in boiled quinoa. In summary, nutritional levels of vitamins vulnerable to heat and unsaturated fatty acids decreased after cooking with heat, while those of amino acids and saturated fatty acids increased after cooking with heat, although there were variables based on different cooking methods.
        4,600원
        620.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was aimed to examine inorganic fouling and fouling reduction method in direct contact membrane distillation(DCMD) process. Synthetic seawater of NaCl solution with CaCO3 and CaSO4 was used for this purpose. It was found in this study that both CaCO3 and CaSO4 precipitates formed at the membrane surface. More fouling was observed with CaSO4(anhydrite) and CaSO4・0.5H2O(bassanite) than CaSO4・2H2O(gypsum). CaCO3 and gypsum were detected at the membrane surface when concentrates of SWRO(seawater reverse osmosis) were treated by the DCMD process, while gypsum was found with MED(multi effect distillation) concentrates. Air backwash(inside to out) was found more effective in fouling reduction than air scouring.
        4,200원