• Title/Summary/Keyword: 자동상관계

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A development of evaluation system of lifting and lowering tasks for energy expenditure at farm work (중량물 들고 내리기 농작업 자세의 에너지 소모량 평가 시스템 개발)

  • Sim, Taeyong;Kim, Bori;Youn, Su Hyun;Mun, Joung Hwan
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • 2017.04a
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    • pp.145-145
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    • 2017
  • 농작업 자세 중에서 중량물을 반복적으로 들고 내리는 자세는 요통과 같은 근골격계 질환의 유발행위로 분류된다. 이는 인간공학적 유해요인 평가도구에 의해 위험도 별로 정량화 할 수 있다. 이러한 평가방법은 농작업 자세를 개선하여 근골격계 질환을 예방할 수 있다는 측면에서 매우 중요하다. 그러나 기존의 작업자세 부하 평가방법들은 동적 자세를 평가하는데 있어 어려움이 있을 뿐 만 아니라 평가 과정에서 관찰자의 주관성이 개입 될 수 있다는 한계점을 갖고 있다. 이에 본 연구에서는 중량물을 들고 내리는 동적 자세에서 발생하는 부하를 Energy expenditure를 이용하여 평가할 수 있는 시스템을 개발하는 것이다. Energy expenditure는 체중, 성별 등과 같은 작업자 관련 변수와 중량물의 무게, 들어 올리는 높이, 빈도수 등과 같은 작업환경 관련 변수를 이용하여 최대 산소소비량을 예측하는 방법이다. 본 연구에서 제안하는 작업자 및 작업환경 관련 변수를 자동 측정하는 시스템은 초음파 거리측정 센서와 깔창 형태의 센서를 이용하여 구성하였다. 이를 통해 남성(6명), 여성(6명)을 대상으로 20kg의 중량물을 들고 내리는 동작에서 발생하는 Energy expenditure 값을 산출하였고, 산소소비량 측정 장비를 통해 획득된 최대 산소소비량($VO_2$)과 비교하여 검증하였다. 여성을 대상으로 한 Energy expenditure 값과 최대 산소소비량 간 상관관계는 0.984로 나타났으며, 남성의 경우에는 0.998로 높은 상관관계를 보였다. 이와 같은 에너지 대사율 평가시스템은 연속적이고 반복적인 실제 농작업 자세 부하를 동적인 상태에서 평가할 수 있을 뿐 만 아니라 산소소비량 측정기와 같은 추가적인 장비가 필요하지 않아 현장 적용성이 뛰어 날 것으로 기대된다.

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Experimental Study on Auto-Transmission Fluid Heat Exchanger for Improving Vehicle Fuel Efficiency (차량 연비개선을 위한 자동변속기유 열교환기에 대한 실험적 연구)

  • Jang, Chung-Man;Lee, Yong-Kyu;Kang, Byeong-Dong;Yoo, Jai-Suk;Lee, Jong-Hwa;Kim, Hyun-Jung;Kim, Dong-Kwon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.9
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    • pp.947-954
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    • 2011
  • Drive-train friction loss in a vehicle may account for 4% of its total fuel consumption loss. An ATF W/C (auto-transmission fluid warmer/cooler) plate-fin heat exchanger is a type of heat exchanger that uses metal plates to transfer heat between the auto-transmission fluid and coolant. The use of an ATF W/C heat exchanger can result in a fuel economy improvement of about 1% in vehicles. An experimental setup for testing the thermal performance of an ATF W/C plate-fin heat exchanger is developed. In this study, the influence of the ATF and coolant, flow rates, and temperature on the efficiency of an ATF W/C heat exchanger are investigated experimentally. From the experimental data, a simple correlation for predicting the efficiency of an ATF W/C heat exchanger is proposed. On the basis of this correlation, the fuel economy of a vehicle with and without an ATF W/C heat exchanger is compared by using Simulink. Finally, it is shown that the fuel economy is improved by 0.992% when an ATF W/C heat exchanger is installed in the vehicle.

실시간 수문자료의 특성분리를 통한 예측성능의 향상

  • Hwang, Seok-Hwan;Kim, Chi-Yeong;Cha, Jun-Ho;Jeong, Seong-Won
    • Proceedings of the Korea Water Resources Association Conference
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    • 2011.05a
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    • pp.128-128
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    • 2011
  • 본 연구에서는 자동유량측정시설에 의하여 실시간으로 생산되는 자동유량측정 자료의 정상성 여부를 판단하는데 중요한 적정 측정 신뢰구간을 실시간으로 예측할 수 있는 기술을 개발하였다. 전세계적으로, 현대적인 유량측정이 시작된 이래 연속유량 산정을 위한 방법은 수위-유량관계곡선을 이용하는 방법 외에 실무적으로 활용 가능한 방법은 거의 전무한 실정이다. 수위-유량관계곡선을 이용하는 방법은 연속수위를 계측하여 이에 해당하는 연속유량을 산정하는 방법으로 수위와 유량간에 일정한 관계를 가지는 정상적인 흐름을 보이는 자연하천의 경우에 정확도가 매우 높다. 그러나 감조나 구조물 등에 의해 유량이 조절되는 경우에 유량산정의 정확도는 현저히 떨어지게 된다. 따라서 수위에서 유량을 환산하는 방법이 아닌 유량을 직접 연속으로 측정하는 방법이 꾸준히 연구되어 왔고, 이 중 가장 대표적인 방법이 자동유량측정 방법이다. 그러나 자동유량측정 방법은 유량을 연속으로 측정할 수 있다는 장점에 반해 측정된 유량의 정확도를 높이기가 매우 어렵다는 단점도 가지고 있다. 계측 자체의 기술적 한계는 주로 계측기기적인 문제로 이는 전자기, 통신 기술 등 첨단 기술의 발전과 함께 다양한 현장 시험을 통해 폭넓은 개선이 이루어지고 있다. 그러나 아직 기술적 완성도가 완전하지 못한 현실에서, 현재 설치되어 있는 자동유량측정 유량자료의 신뢰도를 높이기 위해서는 각각의 계측 시점에서 자료가 정상적으로 산정되고 있는지에 대한 검정이 필요하고, 이는 자동유량측정 자료의 정확도 확보에 매우 중요한 관건으로 작용할 수밖에 없다. 이러한 배경에서 본 연구에서는 조석성분과 유출성분을 분리하여 예측하는 방법을 새롭게 개발 적용하였다. 자료는 자료의 시간해상도 증감에 따른 실제 예측의 정확도 증감을 고려하여 가장 적절하다고 판단되는 시자료를 사용하였으며, 자료간 상관을 분석하여 주 입력 자료로 팔당댐 방류량, 한강대교 지점 수위, 전류 수위를 이용하였다. 모형의 예측 능력을 극대화하기 위하여 조석 영향을 받는 자료의 경우는 웨이블릿 변환(wavelet transform)을 이용하여 순수 유출성분과 조위성분을 분리하여 별도로 적용하였다. 그리고 예측을 위한 모형은 실시간 자료기반 모형으로 그 안정성이 인정된 서포트벡터머신(support vector machine)을 이용하였다. 이러한 과정을 통해 한강대교 지점의 순수 유출성분과 조위성분의 유량을 각각 예측한 후 두 결과를 합성하여 최종 한강 대교 지점의 유량을 산정하였다. 조석성분을 분리하여 한강대교 지점의 유량을 예측한 결과 대부분의 예측치가 95% 예측구간에 포함되었다. 그리고 조석성분을 분리하지 않은 모형과 조석성분을 분리한 모형의 예측 능력을 비교한 결과, 조석성분을 분리한 모형이 예측이 정확도가 높았다. RMSE의 경우 분리하지 않은 모형대비 23%의 예측오차가 감소하였고, NSC의 경우 0.92에서 0.95로 예측의 정확도가 증가하였다.

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A Study on the Cure Behavior of Epoxy Molding Compound (Epoxy Molding Compound의 경화거동에 관한 연구)

  • 윤상영;오명숙;박내정
    • Polymer(Korea)
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    • v.24 no.6
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    • pp.837-844
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    • 2000
  • The cure behavior of commercial epoxy molding compounds (EMC) commonly used for IC package was studied at constant cure temperatures as well as at constant heating rates using differential scanning calorimetry (DSC), rheometer, and dielectric analyzer (DEA). The cure kinetics were obtained using autocatalytic reaction model according to the Ryan Dutta method after assuming m+n equal to 2. The prediction of reaction rates by the model equation corresponded well to experimental data at all temperatures except for 10$0^{\circ}C$. The phase transitions such as gelation and vitrification occurred during network formation. At each isothermal cure temperature, $T_{g}$ was measured in accordance with cure time, and the vitrification point was attained when $T_{g}$ was equal to $T_{cure}$. The temperature dependence of gel points and vitrification points showed good agreement with Arrhenius relation. DEA using parallel plate electrode was effective for the monitoring of EMC cure. we knew that if the resin systems are materials of comparable quality, $_{gel}$$T_{g}$ is constant regardless of accelerator concentration in TTT (Time-Temperature-Transformation) diagram.

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Monitoring soybean growth using L, C, and X-bands automatic radar scatterometer measurement system (L, C, X-밴드 레이더 산란계 자동측정시스템을 이용한 콩 생육 모니터링)

  • Kim, Yi-Hyun;Hong, Suk-Young;Lee, Hoon-Yol;Lee, Jae-Eun
    • Korean Journal of Remote Sensing
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    • v.27 no.2
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    • pp.191-201
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    • 2011
  • Soybean has widely grown for its edible bean which has numerous uses. Microwave remote sensing has a great potential over the conventional remote sensing with the visible and infrared spectra due to its all-weather day-and-night imaging capabilities. In this investigation, a ground-based polarimetric scatterometer operating at multiple frequencies was used to continuously monitor the crop conditions of a soybean field. Polarimetric backscatter data at L, C, and X-bands were acquired every 10 minutes on the microwave observations at various soybean stages. The polarimetric scatterometer consists of a vector network analyzer, a microwave switch, radio frequency cables, power unit and a personal computer. The polarimetric scatterometer components were installed inside an air-conditioned shelter to maintain constant temperature and humidity during the data acquisition period. The backscattering coefficients were calculated from the measured data at incidence angle $40^{\circ}$ and full polarization (HH, VV, HV, VH) by applying the radar equation. The soybean growth data such as leaf area index (LAI), plant height, fresh and dry weight, vegetation water content and pod weight were measured periodically throughout the growth season. We measured the temporal variations of backscattering coefficients of the soybean crop at L, C, and X-bands during a soybean growth period. In the three bands, VV-polarized backscattering coefficients were higher than HH-polarized backscattering coefficients until mid-June, and thereafter HH-polarized backscattering coefficients were higher than VV-, HV-polarized back scattering coefficients. However, the cross-over stage (HH > VV) was different for each frequency: DOY 200 for L-band and DOY 210 for both C and X-bands. The temporal trend of the backscattering coefficients for all bands agreed with the soybean growth data such as LAI, dry weight and plant height; i.e., increased until about DOY 271 and decreased afterward. We plotted the relationship between the backscattering coefficients with three bands and soybean growth parameters. The growth parameters were highly correlated with HH-polarization at L-band (over r=0.92).

Evaluation of the Forest Bird Community in the Breeding Season by using the Sound Recording System (산림성 조류의 번식기 음성녹음을 이용한 조류군집 평가)

  • Yoo, Seung-Hwa;Han, Hyun-Jin;Kim, Dong-Won;Joo, Woo-Young
    • Korean Journal of Environment and Ecology
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    • v.32 no.1
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    • pp.39-46
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    • 2018
  • Breeding bird surveys provide the reference information for understanding bird community structure and function in the ecosystem and conserving biodiversity. Recent rapid change of biodiversity due to climate change and other factors has made it necessary to utilize acoustic sensors for accuracy and spatial expansion of forest bird survey data and for time-series monitoring of forest birds. The objective of this study is to investigate the possibility of using acoustic recording sensor to evaluate the diversity of forest birds at breeding season by comparing and analyzing the recorded data of bird songs and field bird survey data. We conducted the site survey and recording in 186 points in 48 areas of 4 regions of Gombaeryeong and Jochimryeong around Jeombongsan Mountain and Jugryeong and Gochiryeong around Sobaeksan Mountain from May 2nd to 16th in 2013. The analysis of the correlation between the recording result and Bird Community Index based on the field survey showed that the number of bird species, population, and the number of bird songs by recording was significantly correlated to the number of species and population by field survey. Moreover, the number of bird species and the number of bird songs by recording showed a significant correlation to species diversity and species richness but no or low significant correlation to species evenness by the field study (observation and listing in parallel). As a result, it was possible to check species composition and species diversity of bird communities by analyzing acoustic recording data on the field. The acoustic recordings of bird songs in the breeding period were more reliable than the non-breeding period in the correlation of recording result and species diversity and for utilization.

Relationship between Uncorrected Visual Acuity and Refraction of the Children and Teenagers (소아, 청소년의 나안시력과 굴절이상의 상관성 분석)

  • Kim, Sang-Moon;Shim, Hyun-Seok;Shim, Jun-Beom
    • Journal of Korean Ophthalmic Optics Society
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    • v.18 no.2
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    • pp.173-178
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    • 2013
  • Purpose: This study is to predict refractive errors according to uncorrected visual acuity using uncorrected visual acuity of the first glasses wearers. Methods: For 886 children who visited an ophthalmic clinic, subjective refraction was carried out with maintain refraction (MR) and cycloplegic refraction (CR), and objective refraction was carried out using auto-refractometer. Uncorrected visual acuity and corrected visual acuity were tested using on a trial lens and a Han's visual acuity chart. Results: In correlation between with the uncorrected visual acuity and refractive the myopia was the highest (r=0.774) and followed by hyperopia (r=0.670), simple astigmatism (r=0.623), simple with-the-rule astigmatism (r=0.604)and simple against-the-rule astigmatism (r=0.508). Conclusions: There were differences in the predictions between uncorrected visual acuity and refractive error according to the types of refractive error and astigmatism.

Determination of Water Content in Compacted Bentonite Using a Hygrometer and Its Application (습도계를 이용한 압축벤토나이트 내 함수율 결정 및 적용)

  • Lee, Jae-Owan;Cho, Won-Jin
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.7 no.2
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    • pp.101-107
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    • 2009
  • Investigation of resaturation and thermal-hydro-mechanical behavior for the buffer of a repository requires measuring the water content of compacted bentonite. This study investigated the relative humidity of compacted bentonites using a humidity sensor (Vaisala HMT 334) applicable under high temperature and pressure, and then conducted a multi-regression analysis based on the measured results to determine relationships among the water content, relative humidity, and temperature. The relationships for the compacted bentonites with the dry densities of 1,500 $kg/m^3$ and 1,600 $kg/m^3$ were expressed as ${\omega}=0.196RH-0.029T+1.391({r^2=0.96)}$ and ${\omega}=0.199RH-0.029T+2.596({r^2=0.98)}$, respectively. These were then used to interpret the resaturation of bentonite blocks in the KENTEX test.

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Estimation of Soybean Growth Using Polarimetric Discrimination Ratio by Radar Scatterometer (레이더 산란계 편파 차이율을 이용한 콩 생육 추정)

  • Kim, Yi-Hyun;Hong, Suk-Young
    • Korean Journal of Soil Science and Fertilizer
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    • v.44 no.5
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    • pp.878-886
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    • 2011
  • The soybean is one of the oldest cultivated crops in the world. Microwave remote sensing is an important tool because it can penetrate into cloud independent of weather and it can acquire day or night time data. Especially a ground-based polarimetric scatterometer has advantages of monitoring crop conditions continuously with full polarization and different frequencies. In this study, soybean growth parameters and soil moisture were estimated using polarimetric discrimination ratio (PDR) by radar scatterometer. A ground-based polarimetric scatterometer operating at multiple frequencies was used to continuously monitor the soybean growth condition and soil moisture change. It was set up to obtain data automatically every 10 minutes. The temporal trend of the PDR for all bands agreed with the soybean growth data such as fresh weight, Leaf Area Index, Vegetation Water Content, plant height; i.e., increased until about DOY 271 and decreased afterward. Soil moisture lowly related with PDR in all bands during whole growth stage. In contrast, PDR is relative correlated with soil moisture during below LAI 2. We also analyzed the relationship between the PDR of each band and growth data. It was found that L-band PDR is the most correlated with fresh weight (r=0.96), LAI (r=0.91), vegetation water content (r=0.94) and soil moisture (r=0.86). In addition, the relationship between C-, X-band PDR and growth data were moderately correlated ($r{\geq}0.83$) with the exception of the soil moisture. Based on the analysis of the relation between the PDR at L, C, X-band and soybean growth parameters, we predicted the growth parameters and soil moisture using L-band PDR. Overall good agreement has been observed between retrieved growth data and observed growth data. Results from this study show that PDR appear effective to estimate soybean growth parameters and soil moisture.

Varietal Difference in Antioxidative Activity of Ethanolic Extracts from Colored Rice Bran (유색미 에탄올 추출물의 품종간 항산화 활성 변이)

  • Nam, Seok-Hyun;Chang, Su-Min;Kang, Mi-Young
    • Applied Biological Chemistry
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    • v.46 no.1
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    • pp.16-22
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    • 2003
  • Interrelation between the antioxidative activities of 70% ethanol extracts from bran fraction of 23 kinds of colored rice and chuchung as a control were examined. Antioxidative activities were evaluated by assaying reducing power, electron-donation ability to DPPH free radical, scavenging activity of hydroxy radical $({\cdot}OH)$ generated through Fenton reaction and inhibitory activity on lipid peroxidation using linoleic acid autoxidation system, respectively. Among 24 varieties of colored rice LK 1-3-6-12-1-1 had the strongest reducing power followed by Elwee, DZ 78, Jumlalocal-1 and SC-45 in decreasing order. The electron-donating ability to DPPH radical was higher in order of HP 883-1-1-1-B-1-1, HP 833-1-3-1-1-1, LK 2-7-12-1-1 and DZ 78. The hydroxy radical scavenging activity was higher in order of DK-1, IR 1544-38-2-2-1-2-2, SC-5 and SC-45 but LK 2-7-12-1-1 had oxidative effect. In the liaoleic acid autoxidation model system, RGS No 336, LK 1B-2-1-1, LK 1B-4-12-1-1, LK 1A-2-12-1-1, LK 2-7-12-1-1 and HP 883-1-1-1-B-1-1 exhibited strong antioxidative activities but Elwee, Jumlalocal-l and SC-45 showed to have oxidative effects. The rice variety of highest pigment content was Elwee and the next were RGS-No 336, IR 1544-38-2-2-1-2-2 and SC-5 with the order of higher content. The reducing power was correlated with the quantity of the pigment in the ethanolic extract of rice bran and SC-5 showed relatively high antioxidative activity in every results of antioxidative activity tests.