• 한국초지조사료학회지
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• 제18권2호
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• pp.89-94
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• 1998

A field experiment was carried out to determine the effects of chemical drying agents at mowing on the field drying rate of alfalfa (cv. Vernal) and rye (cv. Koolgrazer) for hastening hay manuf8cture. In alfalfa; chemicals ($K_2CO_3$ 2% $K_2CO_3$ 3% $Na_2CO_3$ 2% $CaCO_3$, 2% $K_2CO_3$2% + $Na_2CO_3$, 1% only water spray and control) were treated at early bloom stage in 1995. Chemicals ($K_2CO_3$, 2%, $Na_2CO_3$, 2% $CaCO_3$, 2% and control) were applicated at different harvest stages (early heading, heading and bloom) in rye, 1996. The drying rate of alfalfa by $K_2CO_3$ treatment among chemicals was higher than control, and the duration of field dry was shortened by one day with $K_2CO_3$ application, but there was no difference in drying efficiency between $K_2CO_3$ 2% and $K_2CO_3$ 3%. In rye, however, no moisture reduction by chemicals was observed. The days required for field dry were 6, 4, and 3 days at warly heading heading and bloom stage respectively; regardless of chemical drying agents and conbol. The nutritive value of rye hay with chemicals at baling was very slightly higher than control, but there was no significant difference. Also, no difference of hay quality was found among drying agents. In conclusion, $K_2CO_3$can enhance the field drying rate of alfalfa hay, but the drying efficiency was not high, particularly in rye hay. Harvesting at early heading to heading stage was desirable for manufacture of high quality rye hay.

• 대한전기학회논문지
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• 제35권2호
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• pp.55-61
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• 1986

This paper describes the generation region and suppression effect of the abnormal field voltage induced when the synchronous generator is switched to the infinite bus, the critical value of negative field current is calculated by simmulation which has parameters of the phase difference and voltatge ratio between the bus and the generator. The suppression effect of discharge resistance connected in parallel with the field circuit is also investigated. According to this study, the optimal value of discharge resistance which can suppress effectively the abnormal field voltage may be calculated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.3-5
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• 1997

The relation between electric current and magnetic field under three overhead transmission lines being operated was studied. It was examined for a difference each other in comparison with calculated value and measured value for current, magnetic field. With magnetic field equations made out, The magnetic field distribution around transmission lines had made to figure out with easy by load electric current value. Additionally, we are going to describe the distribution curve of magnetic exposure volume for KEPCO's T/L.

• 한국전기전자재료학회논문지
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• 제36권4호
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• pp.408-412
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• 2023

In this paper, in order to analyze high electrical insulation and cooling performance using mineral oil, the liquid insulating oil was changed in electrode shape and distance between electrodes to compare and analyze electrical characteristics according to equal electric field, quasi-equivalent electric field, and unequal electric field. As a result, the breakdown voltages were 36,875 V and 36,875 V in the form of sphere-sphere and plate-plate electrodes with equal electric fields. The breakdown voltage was 31,475 V in the sphere-plate electrode type, which is a quasi-equilibrium field, and the breakdown voltage was 28,592 V, 27,050 V, and 22,750 V in the needle-needle, sphere-needle, and needle-plate electrode types, which are unequal fields. Through this, it is possible to know the difference in breakdown voltage according to the type of electric field. The more equal the field, the higher the breakdown voltage, and the more unequal field, the lower the breakdown voltage. The difference in insulation breakdown voltage could be seen depending on the type of electric field, the insulation breakdown voltage was higher for the more equal electric field, and the insulation breakdown voltage was lower for the more unequal electric field. Also, it was confirmed that the closer the distance between the electrodes, the higher the insulation breakdown voltage, the higher the insulation breakdown current, and the insulation breakdown voltage and the insulation breakdown current were proportional.

• 한국병원경영학회지
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• 제21권3호
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• pp.11-21
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• 2016

The purpose of this study is to investigate the degree of difficulty and turnover of nurses working in the field and to derive clinical work activation and supply policy improvements. Data was collected from December, 2014 to January, 2015, from 23 hospitals, and participants were 3,887 nurses working in the field, Survey details : the difficulty of the clinical work of nurses working in hospitals, turnover intentions status and policy proposals for clinical research work enabled General characteristics, difficulties in clinical working, turnover intention and clinical work plan activation are frequency analysis. The difference between each of the variables in accordance with the general characteristics are one-way ANOVA analysis, Correlation analysis of the variables is also a Pearson correlation coefficients. 'difficulties in clinical working' was a statistically significant difference depending on the type of hospital, nursing class, number of beds, location, age, position, employment, gender, working form, working department, salary, career, and degree level. 'turnover intention' was a statistically significant difference depending on nursing rate, number of beds, region, age, position, sex, shifts, departments, annual income, and career. 'policy recommendation' was a statistically significant difference depending on type of hospital, nursing rate, age, position, employ, shifts, departments, annual income, degree level and career 'difficulties in clinical working' is 'turnover intention' (p<.001), 'policy recommendations' (p<.001) and had a significant positive correlation. and 'turnover intention' had a "policy recommendation" significant positive correlation with the relationship (p<.001) The most difficulties point of the nurses working in the field are the environment, such as shift, urgent and dangerous. Major policy proposals are improve treatment such as wages, and welfare.

• 인간식물환경학회지
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• 제24권4호
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• pp.441-450
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• 2021

Background and objective: The purpose of study is to analyze the three-dimensional (3D) structure by creating a 3D model for green spaces in a park using unmanned aerial vehicle (UAV) images. Methods: After producing a digital surface model (DSM) and a digital terrain model (DTM) using UAV images taken in Mureung Park in Chuncheon-si, we generated a digital tree height model (DHM). In addition, we used the mean shift algorithm to test the classification accuracy, and obtain accurate tree height and volume measures through field survey. Results: Most of the tree species planted in Mureung Park were Pinus koraiensis, followed by Pinus densiflora, and Zelkova serrata, and most of the shrubs planted were Rhododendron yedoense, followed by Buxus microphylla, and Spiraea prunifolia. The average height of trees measured at the site was 7.8 m, and the average height estimated by the model was 7.5 m, showing a difference of about 0.3 m. As a result of the t-test, there was no significant difference between height values of the field survey data and the model. The estimated green coverage and volume of the study site using the UAV were 5,019 m² and 14,897 m³, respectively, and the green coverage and volume measured through the field survey were 6,339 m² and 17,167 m³. It was analyzed that the green coverage showed a difference of about 21% and the volume showed a difference of about 13%. Conclusion: The UAV equipped with RTK (Real-Time Kinematic) and GNSS (Global Navigation Satellite System) modules used in this study could collect information on tree height, green coverage, and volume with relatively high accuracy within a short period of time. This could serve as an alternative to overcome the limitations of time and cost in previous field surveys using remote sensing techniques.

• 대한방사선치료학회지
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• 제12권1호
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• pp.91-104
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• 2000

Recently linear accelerator in radiation therapy in asymmetric field has been easily used since the improvement and capability of asymmetrical field adjustment attached to the machine. It has been thought there have been some significant errors in dose calculation when asymmetrical radiation fields have been utilized in practice of radiation treatments if the fundamental data for dose calculation have been measured in symmetrical standard fields. This study investigated how much the measured data of dose distributions and their isodose curves are different between in asymmetrical and symmetrical standard fields, and how much there difference affect the error in dose calculation in conventional method measured in symmetrical standard field. The distributions of radiation dose were measured by photon diode detector in the water phantom (RFA-300P, Scanditronix, Sweden) as tissue equivalent material on utilization of 6 MV linear accelerator with source surface distance (SSD) 1000 mm. The photon diode detector has the velocity of 1 mm per second from water surface to 250 mm depth in the field size of $40mm{\times}40mm\;to\;250mm{\times}250mm\;symmetric\;field\;and\;40mm{\times}20mm\;to\;250mm{\times}125mm$ asymmetrical fields. The measurements of percent depth dose (PDD) and subsequent plotting of their isodose curves were performed from water surface to 250mm dmm from Y-center axis in $100mm{\times}50mm$ field in order to absence the variability of depth dose according to increasing field sizes and their affects to plotted isodose curves. The difference of PDD between symmetric and asymmetric field was maximum $4.1\%\;decrease\;in\;40mm{\times}20mm\;field,\;maximum\;6.6\%\;decrease\;in\;100mm{\times}50mm\;and\;maximum\;10.2\%\;decrease\;200mm{\times}100mm$, the larger decrease difference of PDD as the greater field size and as greater the depth, The difference of PDD between asymmetrical field and equivalent square field showed maximum $2.4\%\;decrease\;in\;60mm{\times}30mm\;field,\;maximum\;4.8\%\;decrease\;in\;150mm{\times}75mm\;and\;maximum\;6.1\%\;decrease\;in\;250mm{\times}125mm$, and the larger decreased differenced PDD as the greater field size and as greater the depth, these differences of PDD were out of $5\%$ of dose calculation as defined by international Commission on radiation unit and Measurements(ICRU). In the dose distribution of asymmetrical field (half beam) the plotted isodose curves were observed to have deviations by decreased PDD as greater as the blocking of the beam moved closer to the central axis, and as the asymmetrical field increased by moving the block 10 mm keeping away from the central axis, the PDD increased and plotted isodose curves were gradually more flattened, due to reduced amount of the primary beam and the fraction of low energy soft radiations by passing thougepth in asymmetrical field by moving independent jaw each 10 h beam flattening filter. As asymmetrical radiation field as half beam radiation technique is used, the radiation dosimetry calculated in utilizing the fundamental data which measured in standard symmetrical field should be converted on bases of nearly measured data in asymmetrical field, measured beam data flies of various asymmetrical field in various energy and be necessary in each institution.

• Radiation Oncology Journal
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• 제5권2호
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• pp.157-163
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• 1987

It is known that fixed source to skin distance (SSD) cannot be used when the treatment field is sloped or larger than the size of second collimator in electron beam irradiation and inverse square law using effective ssd should be adopted. Effective SSDs were measured in different field sizes in each 6, 9, 12, 15 and 18MeV electron energy by suing NELAC 1018D linear accelerator of Kosin Medical Center. We found important parmeters of effective SSD. 1. Minimum effective SSD was 58.8cm in small field size of $6\pm6cm$ and maximum effective SSD was 94.9cm in large field size of $25\pm25cm$, with 6MeV energy. It's difference was 36.1cm. The dose rate at measuring point was quite different even with a small difference of SSD in small field $(6\times6cm)$ and low energy (6 MeV). 2. Effective SSD increased with field size in same electron energy. 3. Effective SSDs gradually increased with the electron energies and reached maximum at 12 or 15 MeV electron energy and decreased again at 18MeV electron energy in each identical field size. And so the effective SSD should be measured in each energy and field size for practical radiotherapy.

• 한국주거학회논문집
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• 제16권4호
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• pp.73-80
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• 2005

A high-rise residential building experienced stack effect problems during the winter such as difficulties in opening residential entrance doors and whistling noise from elevator doors generated by airflow. Field measurements were carried out on the building and the problems were verified by the analysis of the measurement results from three points of view: the total stack pressure difference, pressure distribution on each floor, and the location of the neutral pressure level. Based on the analysis of the three key parameters, possible solutions were proposed, such as zoning vertical shafts, lessening the airflow from the entrance doors on basement floors and lobby floor by installing vestibules, improving the airtightness of exterior walls, and installing separation doors where the problems occur. Simulations of proposed solutions were conducted and the effects of reducing the pressure difference were evaluated. Stack effect problems in a high-rise residential building were verified through field measurements and could be mitigated by the solutions which were drawn from the analysis of the field measurements and the simulation results.

• 한국자기학회지
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• 제5권2호
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• pp.99-102
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• 1995

전기장 기울기 텐서가 축대칭인 결정에 대칭인 방향으로 자기장을 가하면 핵사중극공명에 미치는 Zeeman 효과에 의하여 두 개의 분리된 공명진동수가 측정된다. 이 때 가해준 자기장과 두 공명진동수 간의 차이는 서로 비례하며, ${(CH_{2})}_{6}N_{4}$ 단결정의 $^{14}N$ 원자핵에 대한 비례상수는 0.16 mT/kHz 이다. 핵 사중극 공명장치 와 개인용 컴퓨터를 interface 하여 핵 사중극 공명신호의 모습을 모니터에 표시하여 측정되는 두 공명신호의 진동수 차이로 자기장을 직접 읽을 수 있도록 하였다. 여기로부터 핵 사중극 공명 Gaussmeter를 이용하여 실험적으로 측정한 최저 자기장은 0.20 mT 였다.