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        검색결과 290

        42.
        2018.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to verify the effects of a port throttling and 1/4 diagonal port masking of an intake port of an SI engine. The fuel consumption rate increased with port throttling and masking under all operating conditions. However, the rapid combustion effect was increased in all operating conditions. It is consider that this is more influential on the suction resistance than the combustion efficiency increase through intake control. In addition, the increase in the burning velocity indicates that the flame propagation speed is increased by increasing the swirl moment during combustion.
        4,000원
        43.
        2018.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we have investigated the optimal control method and the energy saving possibility when the dimming control for lighting and the suspended particles display(SPD) glass for window were applied to reduce the lighting load and the cooling load in office buildings. Simulations were carried out during from 8:00 am to 7:00 pm of typical one day on summer, winter and intermediate season. Simulation results showed that the cooling and lighting energy usage was reduced to 21.2% compared to the baseline model. Therefore, it was possible to predict the optimum control method of the suspended particles display(SPD) window to control the transmittance for energy saving and the dimming control for lighting during summer season.
        4,000원
        44.
        2018.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        온실의 냉난방부하 산정을 위해 설계자가 선택해야할 주요 변수들에 대하여, 이들 설계 변수가 냉난방부하에 미치는 영향을 평가하기 위해서 각각의 설계 변수값을 변화시키면서 시뮬레이션을 실시하였으며, 이를 바탕으로 특별히 선택에 주의를 기울여야 할 설계 변수를 제안하였다. 난방부하에 가장 큰 영향을 미치는 설계 변수는 피복재의 열관류율이고, 다음으로 설계외기온인 것으로 나타났다. 연동수에 따른 설계 변수의 영향은 차이가 거의 없는 것으로 나타났다. 단동 온실의 경우에는 지중전열 관련 설계 변수의 영향을 무시할 수 없을 것으로 생각되지만, 연동 온실의 경우에는 지중전열 관련 변수 및 틈새환기율의 영향이 미미한 것으로 판단되었다. 냉방부하에 가장 큰 영향을 미치는 설계 변수는 온실내로 유입되는 일사량과 증발산계수이고, 다음으로 실내외 기온차, 환기율인 것으로 나타났다. 설계 변수의 영향은 단동 온실과 연동 온실에서 큰 차이를 보였으나, 연동수에 따른 차이는 거의 없는 것으로 나타났다. 피복재의 열관류율은 단동 온실이나 연동 온실 모두 영향이 미미한 것으로 나타났지만, 실내외 기온차 및 환기율의 경우에는 냉방부하에 미치는 영향을 무시할 수 없을 것으로 생각되며, 특히 연동 온실에서 그 영향이 더 큰 것으로 판단되었다. 냉방부하를 산정할 때 실내 목표온도를 낮게 설정할수록 설계 변수의 선택에 신중해야 한다. 특히, 실내 목표온도를 외기온 보다 낮게 설정하면 환기율 및 열관류율 값이 냉방부하를 증가시키는 방향으로 바뀌므로 더욱 주의해야 한다. 환기율이 낮을 때는 설계 변수 중 설계일사량과 증발산계수의 선택에 주의해야 하고, 환기율이 높을 때는 실내 설정온도와 설계외기온의 선택에 신중을 기해야 한다.
        4,000원
        46.
        2018.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The annual total phosphorus load caused by public wastewater, nightsoil and livestock manure treatment facilities in Korea has been examined macroscopically. Annual domestic average phosphorus (P) inflows through the income of phosphate rock for the last five years (2012 - 2016) were analyzed as 76,598 tons/year. As of the year 2015, the total loadings of phosphorus attributed to public wastewater treatment facilities, nightsoil treatment facilities and livestock wastewater were estimated as 30,269 tons/year, 1,909 tons/year and 18,138 tons/year, respectively. Considering the amount of phosphorus imports, the annual phosphorus load from wastewater, livestock wastewater and excretions is equivalent to 39.5%, 23.7%, 2.5% and totally 65.7%(39.5% + 23.7% + 2.5%). Therefore, the introduction of phosphorus recovery and recycling processes for the public wastewater and livestock manure treatment facilities has been found to be effective because it could reduce the import amount of phosphate rock by up to 60% or more.
        4,300원
        47.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Two climate change scenarios, the RCP (Representative Concentration Pathways) 4.5 and the RCP 8.5 in the fifth Assessment Report (AR5) by Intergovernmental Panel on Climate Change (IPCC), were applied in the Yocheon basin area using the SWAT (Soil and Water Assessment Tool) model to estimate changes in flow rates and pollutant loadings in the future. Field stream flow rate data in Songdong station and water quality data in Yocheon-1 station between 2013~2015 were used for model calibration. While R2 value of flow rate calibration was 0.85 and R2 value of water qualities were in the 0.12~0.43 range. The total study period was divided into 4 sub periods as 2030s (2016~2040), 2050s (2041~2070) and 2080s (2071~2100). The predicted results of flow rates and water quality concentrations were compared with results in calibrated periods, 2015s (2013~2015). In both RCP scenarios, flow rate and TSS (Total Suspended Solid) loadings were estimated to be in increasing trend while TN (Total Nitrogen) and TP (Total Phosphorus) loadings showed decreasing patterns. Also, flow rates and pollutant loadings showed larger differences between the maximum and the minimum values in RCP 4.5 than RCP 8.5 scenarios indicating more severe effect of drought and flood, respectively. Dependent on simulation period and rainfall periods in a year, flow rate, TSS, TN and TP showed different trends in each scenario. This emphasizes importance of considerations on time and space when analyzing climate change impacts of each variable under various scenarios.
        4,500원
        48.
        2018.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to investigate the runoff characteristics of nonpoint source pollutants in the Lake Doam watershed, water quality and flow rate were monitored for 38-rainfall events from 2009 to 2016. The EMC values of SS, COD, TN and TP were in the range of 33~2,169, 3.5~56.9, 0.09~7.65 and 0.06~2.21 mg L-¹, respectively. As a result of analyzing the effect of rainfall factor on the nonpoint source pollutant load, EMCs of SS, COD and TP showed a statistically significant correlation with rainfall (RA) (p<0.01) and SS showed highly significant correlation with maximum rainfall intensity (MRI, R=0.48). The load ranges of SS, COD, TN and TP were 10.4~11,984.6, 1.1~724.4, 0.6~51.6 and 0.03~22.85 ton event-¹, respectively, showing large variation depending on the characteristics of rainfall events. The effect of rainfall on the load was analyzed. SS, COD and TP showed a positive correlation, but TN did not show any significant correlation. The annual load of SS was the highest with 88,645 tons year-¹ in 2011 when rainfall was the highest with 1,669 mm. The result of impact analysis of nonpoint source pollution reduction project and land-use change on runoff load showed that pollutant load significantly reduced from 2009 to 2014 but SS and TP loads were increased from 2014 to 2016 due to increase in construction area. Therefore, we suggested that nonpoint source pollution abatement plan should be continued to reduce the soil loss and pollutants during rainfall, and countermeasures to reduce nonpoint source pollution due to construction need to be established.
        4,500원
        49.
        2018.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the loading rates (or emission rate) and concentrations of air pollutants (ammonia, hydrogen sulfide, carbon dioxide, methane, nitrous oxide, and particulate matter (PM2.5, PM10 and TSP)) emitted from a naturally ventilated dairy facility were analyzed and compared to enable a better understanding that are in close proximity to each other, air pollution status. In general, the pollution patterns should be similar in measurement sites that are in close proximity to each other, and this hypothesis was fundamental to our approach in this study. For the comparison in nearby different sites, monitoring points were located at inside (source site) and outside the dairy building (ambient site), and concentrations and wind velocity were simultaneously monitored in real time. The patterns of PM2.5 emission rate and loading rate were similar in the source site and the ambient site which was consist with the hypothesis, while the PM2.5 mass concentration were not similar in both sites. As well as PM2.5, the emission rates (source site) of gaseous carbon dioxide (CO2) and nitrous oxide (N2O) were highly correlated to their loading rates (ambient site), while the concentrations of CO2 and N2O were not similar. Therefore, wind velocity, which is included in the emission or loading rate, should be simultaneously monitored with the concentration at the same measurement points for better understanding of the air pollution status.
        4,000원
        50.
        2018.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구의 목적은 상사의 코칭리더십이 부하직원의 개인 창의성에 미치는 영향을 분석하는 데 있다. 이를 위해 국내 중·소·대기업 제조회사에 종사하는 직장인 총 303명을 대상으로 조사를 실시하였다. 자료 분석은 SPSS 22.0의 통계프로그램을 이용하여 기술통계분석, 평균차이 분석, 상관관계분석, 다중선형회귀분석을 실시하였다. 본 연구의 실증분석결과는 다음과 같다. 첫째, 상사의 코칭리더십과 부하직원의 개인 창의성은 평균 이상의 인식수준을 가지고 있는 것으로 나타났다. 상사의 코칭리더십은 개발, 관계, 수행평가, 방향제시 순으로 나타났으며, 부하직원의 개인 창의성은 지식과 경험, 과제동기, 창 의적 사고기술 순으로 나타났다. 둘째, 인구통계학적 변인에 따른 부하직원의 개인 창의성 차이 검증결과, 성별, 학력, 직급, 상사와의 근무기간, 현 직장 근무기간에서 유의한 차이가 있는 것으로 나타났다. 셋째, 부하직원이 인식한 상사의 코칭리더십과 부하직원의 개인 창의성 간의 상관관계를 살펴 본 결과, 상사의 코칭리더십과 부하직원의 개인 창의성은 전체적으로 유의한 상관관계가 있는 것으로 나타났으며 하위요인으로는 코칭리더십의 관계와 개인 창의성의과 제동기가 높은 상관관계가 있는 것으로 확인되었다. 넷째, 상사의 코칭리더십은 부하직원의 개인 창의성에 유의한 영향력을 미치는 것으로 나타났다. 하위요인으로는 코칭리더십의 방향제시와 관계가 부하직원의 개인 창의성에 영향을 미치고, 개발과 수행평가는 통계적으로 유의한 영 향을 미치지 않는 것으로 나타났다. 이상의 결과를 바탕으로 볼 때 상사의 코칭리더십을 개발함으로써 부하직원의 개인 창의성을 높일 수 있도록 상사의 다양한 코칭리더십교육과 일대일 및 그룹, 팀코칭서비스 등의 기회 제공을 위한 환경 마련이 필요하다.
        6,000원
        51.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 4연동 벤로형 유리온실의 냉·난방 부하를 고려한 PV 시스템의 적정 패널 설치 면적을 도출하기 위하여 BES 기법을 이용하여 온실 및 PV 시스템의 에너지 모델을 설계하였으며 동적 에너지 시뮬레이션을 수행하였다. 대상 작물은 파프리카로 선정하였으며 작물의 적정생육온도를 고려하여 냉·난방장치 및 환기장치의 가동조건을 설정하였다. 2012년부터 2016년까지 총 5년 동안의 기간별 냉·난방부하 및 최대 냉·난방 부하를 환 기팬의 환기량 조건 별로 분석을 실시하였다. 온실의 냉 ·난방 부하 산정과 함께 PV 시스템의 설치 각도에 따른 전력 생산량을 분석하였으며 신재생에너지 공급의무비율을 적용하여 최적 PV 시스템 설계 방안을 도출하였다. 환기팬의 환기량 60AE·hr-1 조건에서 대상 온실의 기간 평균 냉방 부하로 인한 전력 소모량은 174,310kWh, 기간 평균 난방 부하로 인한 전력 소모량은 458,903kWh 로 총 633,213kWh의 전력 소모량이 산정되었다. PV 시스템은 설치 각도를 30o로 설정하는 조건에서 가장 높은 전력 생산량이 나타났으며 월별 최적 각도를 적용하는 조건에서는 고정형 PV 시스템보다 약 5.7% 많은 전력 을 생산하는 것으론 산정 되었다. 최종적으로 대상 온실에 적합한 PV 시스템 패널 면적을 도출한 결과, 고정형 PV 시스템은 521m2의 패널이 필요한 것으로 산정되었고, 가변형 PV 시스템의 경우 494m2의 패널이 필요한 것으로 산정되었다. 본 연구를 통하여 4연동 벤로형 유리온실의 냉·난방 부하를 고려한 PV 시스템의 필요 패널 설치 면적을 도출할 수 있었으며 PV 시스템의 온실 적용 가능성 및 경 제성 평가의 기초 자료로 활용 가능할 것으로 판단된다. 한편, 본 연구에서는 작물 특성 데이터를 확보하지 못하여 작물의 에너지 교환을 고려하지 않았다. 보다 정확한 결과를 도출하기 위해서는 현장 실험 데이터에 기반을 둔 추가 연구가 필요할 것으로 판단된다.
        4,000원
        53.
        2017.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, a winch and load motion control system design method is introduced. Especially, the winch and load (moving cart) are connected with long wire rope which is extended to few kilometers long. Therefore, the rope length changes such that many dynamic parameter values are changed as well by winding and releasing the rope from the winch system. In this paper, the authors designed the control system by considering the real time parameter variation to occupy and keep good control performance continuously. The effectiveness of introduced method was evaluated by simulation results.
        4,000원
        54.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구의 목적은 상사의 코칭리더십이 부하직원의 조직몰입에 미치는 영향을 심리적 안녕 감의 매개변수를 활용하여 분석하는데 있다. 이러한 연구목적을 달성하기 위해서, 기업에 종사 하는 직장인을 대상으로 2015년 8월 16일∼ 9월 5일까지 3주간에 걸쳐 Google의 문서도구를 활용하여 온라인으로 설문을 실시하였다. 총 345부의 회수된 설문지 중에서 유효하지 않은 응 답건수 28부를 제외한 최종 317부를 연구에 사용하였다. 연구결과는 다음과 같다. 첫째, 상사의 코칭리더십과 부하직원의 심리적 안녕감은 모두 평균 이상의 인식수준을 가지 고 있는 것으로 나타났고, 조직몰입도 평균 이상인 것으로 나타났으나, 심리적 안녕감, 코칭리 더십에 비해 전체 평균수준은 다소 낮은 것으로 나타났다 둘째, 부하직원이 인식한 상사의 코칭리더십과 부하직원의 조직몰입, 심리적 안녕감 간의 상관관계를 살펴본 결과 상사의 코칭리더십과 부하직원의 심리적 안녕감 및 조직몰입은 전체 적으로 유의한 상관관계를 가지는 것으로 나타났다. 셋째, 상사의 코칭리더십이 부하직원의 조직몰입과 심리적 안녕감에 미치는 영향력으로는 상사의 코칭리더십이 높아질수록 부하직원의 조직몰입과 심리적 안녕감이 높아지는 것으로 나타났다. 넷째, 부하 직원이 인식한 상사의 코칭리더십과 부하직원의 조직몰입의 관계에서 부하직원 의 심리적 안녕감이 부분매개 역할을 하는 것으로 나타났다.
        6,100원
        55.
        2017.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to investigate the microbial loads in mulberry fruits depending on cultivation environment and fruit ripeness. The population levels of total aerobic bacteria in mulberry fruits collected from open field orchards were higher than those from three plots protected within plastic green houses. In regards to fruit ripeness, the levels of total aerobic bacteria in ripe black fruits were higher than those in unripe green and red mulberry. From the farms into where livestock animals were allowed to enter, Escherichia coli was detected in soil at a level of 4.26~4.94 log CFU/g and in mulberry fruits at 5.03~6.07 log CFU/g, while no coliform and E. coli were detected from where the intrusion of livestock was prevented. We also examined the density change of inoculated E. coli in mulberry fruits as they were becoming mature. While E. coli did not increase in green fruits, two and four log CFU/g increases at 20oC and 37oC, respectively, were observed with red and fully mature black mulberries during 48 hours incubation. To ensure the food safety of mulberry, it is suggested that the introduction of E. coli into a farm through livestock should be prevented and more hygienic caution should be taken especially when the fruits are ripe.
        4,000원
        56.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For driver convenience, different types of transmission are being developed, such as AT(Automatic Transmission), AMT(Automated Manual Transmission), CVT(Continuously Variable Transmission) and DCT(Dual Clutch Transmission). To improve ride comfort and durability of the transmission, control system is important during launching and shifting process. For accurate control, vehicle mass and road gradient should be known. In this study, heavy duty vehicle’s mass and road gradient estimation method is developed. The method uses only signals from CAN(Controller Area Network) without applying extra sensors. Vehicle mass and gradient is estimated by LMS(Least Mean Square) method based on longitudinal vehicle dynamic model. To verify the estimation logic, test was conducted using a chassis dynamometer. The estimation results after test and test condition is compared. The error rate of vehicle mass estimation was 5 percent and gradient estimation result had 2 percent error.
        4,000원
        57.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The efficiency of the purchasing and procurement logistics is important in automotive industry. The rationalization of production system is directly impact on productivity and quality. For this reason importance of logistics is high. Despite we are continuously making effort, our country are still below the level than developed country on logistics efficiency. Rising labor costs is an important factor in increasing logistics costs. So workforce reduction in logistics department is a large part. We deal with A-company inbound logistics, especially procurement logistics in automotive logistics as research object. So in this study we do research on work load balance about workers. We do research on 1,475 kinds of components in procurement process. We applied work load balance algorithm on chassis, final, sequence, trim warehouses workers. According to number of workers and average M/H, algorithm is applied in two ways. After applied work load balance algorithm we reduced numbers of workers from 28 to 20 and improved worker load balance rate from 47.1% to 93.7%
        4,000원
        59.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: In the treatment of temporomandibular joint (TMJ) disorder, the goals of traditional physical therapy are not only to reduce the inflammatory process leading to pain, but also to decrease joint overload and muscle hyperactivity. To achieve those goals, physical therapists generally use a photo-therapy, joint mobilization, and massage. Objects: To examine the impact of an unloading technique using non-elastic taping on the pain, opening mouth, functional level, and quality of life in patients with TMJ disorder. Method: Twenty patients with TMJ disorder were included in this study and randomly divided into the experimental (n1=10), and control (n2=10) groups. Traditional physical therapy including massage and stretching for 30 min was performed in both groups. Non-elastic taping was performed in the experimental group after traditional physical therapy, and they were recommended to keep the tape attached for 12 hours. Outcomes for pain, functional level, and quality of life were measured using a survey. The opening mouth was measured using a general ruler. Result: Significant differences were observed in the pain level, opening mouth, functional level, and quality of life after the intervention and on follow-up in both groups. However, we found that while the levels of all parameters were maintained throughout the follow-up period in the experimental group, the functional status level was not maintained throughout the follow-up period in the control group. Conclusion: Our unloading technique using non-elastic tape results comparable to those achieved by traditional physical therapy in the treatment of TMJ. However, the unloading taping method using non-elastic tape is more effective than traditional physical therapy in maintaining the impact of intervention
        4,200원
        60.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Peak load rate(i.e., maximum daily flow/average daily flow) has not been considered for industrial water demand planning in Korea to date, while area unit method based on average daily flow has been applied to decide capacity of industrial water treatment plants(WTPs). Designers of industrial WTPs has assumed that peak load would not exist if operation rate of factories in industrial sites were close to 100%. However, peak load rates were calculated as 1.10~2.53 based on daily water flow from 2009 to 2014 for 9 industrial WTPs which have been operated more than 9 years(9-38 years). Furthermore, average operation rates of 9 industrial WTPs was less than 70% which means current area unit method has tendency to overestimate water demand. Therefore, it is not reasonable to consider peak load for the calculation of water demand under current area unit method application to prevent overestimation. However, for the precise future industrial water demand calculation more precise data gathering for average daily flow and consideration of peak load rate are recommended.
        4,000원
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