• Journal of Biosystems Engineering
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• 제38권2호
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• pp.81-86
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• 2013

Purpose: Recently, domestic and abroad consumption of mushroom has been increasing. Especially, oyster mushroom has been the most consumed product, sharing one third of the mushroom market. The air temperature differences between relative positions of the mushroom farms were needs to be minimal. However, in reality, the air temperature differences ranged from 2 to $5^{\circ}C$. Because of this, the mushrooms are non-uniform growth as well as decrease in both quality and quantity. Although air circulators have been employed by oyster mushroom farms to minimize air temperature differences, no experiments have been performed to illustrate the effect of the air circulators. Methods: This experiment is designed to analyze the effect of the air circulation by constructing a prototype air circulator and measuring the air temperature when the circulator was position at different heights (50 cm, 150 cm, 200 cm) from the floor in the center. Result: The horizontal plane air temperature of the first growing bed when the air circulator was installed 50cm above the floor in the center, once not using the air circulators and the other time using the air circulators, yielded the air temperature differences of $8.6^{\circ}C$ and $1.8^{\circ}C$ and deviations of 2.82 and 0.60, respectively. The third growing bed's air temperature differences were $10.0^{\circ}C$, $1.6^{\circ}C$ and deviations 3.28, 0.64, each respectively. These outcomes proved that the use of air circulators minimized the air temperature difference and deviation. The use of air circulators helped minimize the air temperature differences and the derivations in oyster mushroom farm. Conclusion: The use of air circulators helped balance the air temperature distribution in oyster mushroom farm.

• Journal of Engineering Education Research
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• 제11권3호
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• pp.33-43
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• 2008

In this paper, mechatronics education in South Korea is analyzed and its improvement is proposed. For this purpose, discussion on the definition and evolution of mechatronics in South Korea, USA and EU is deployed first. It is revealed that most of the mechatronics education in USA and EU is remained in cross-disciplinary stage or curriculum stage, whereas that in South Korea is evolved to curriculum stage or organizational stage. The comparison of mechatronics curriculum between Korea and other countries and the problems of mechatronics education are included. The automation of machinery and factory plays one of major roles in mechatronics education in Korea, while mechatronics curriculum in USA and EU does not emphasize the automation. Mechatronics experiment in South Korea is organized to meet the National Qualification Test on mechatronics, and it is recommended to be more inventive. The way of improving the National Qualification Test of South Korea on mechatronics field is proposed. And, finally, efficient way of linking technical high school and university in mechatronics education is also proposed.

• Korean Journal of Optics and Photonics
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• 제16권3호
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• pp.177-181
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• 2005

Although there are many ways to measure the diameter of a cylindrical object, in this study, the diameter of a cylindrical objects were measured by the geometric optical method and interference-diffraction method which are two kinds of tipical non-contact methods. In geometric optical method, the curved laser beam is formed on the cylindrical surface by spreading the inclined laser beam using the cylindrical lens. The curve is captured by CCD camera and the diameter is calculated by geometry. And the interference and diffraction patterns of investigated cylindrical objects are analyzed in interference-diffraction method. In this study, the cylindrical objects, whose diameters are $0.05\;mm\;\~\;100.50\;mm$ were measured by the geometric optical method and interference-diffraction method. The results show that in each method, the relative errors of the measurement are within $2\%$ and $1\%$, respectively and these non-contact methods can be applied in the quick measurement of many objects.

• Korean Journal of Agricultural Science
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• 제43권3호
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• pp.424-431
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• 2016

The nutrients in livestock manure produced during fermentation processes in public livestock recycling centers are used as fertilizers. However, the large amounts of swine manure produced in intensive livestock farms can be a nonpoint source of pollution. In this experiment, we investigated the chemical properties, inorganic components, and heavy metal contents in 101 samples of liquid swine manure collected from 28 public livestock recycling centers throughout the nation. Results showed that the average pH of the samples was alkaline (pH range 5.18 to 9.54), and their maximum EC was $53.2dS\;m^{-1}$. The amounts of total nitrogen and total phosphorus were in the range of 1000 - 2000 and $200-800mg\;L^{-1}$ while potassium, which constituted 47% of the total inorganic ions recovered from the liquid swine manure, amounted to $1500mg\;L^{-1}$. The most distinctive heavy metals recovered from the liquid swine manure were copper and zinc although the amounts of both heavy metals were much lesser than those of the standards as livestock liquid fertilizer set by the Rural Development Administration. On the other hand, the amount of nitrogen decreased rapidly with an increasing fermentation period from immature to mature, assumed to be lost as volatile compounds, such as ammonia, which are the major odor components during the fermentation process.

• Korean Journal of Agricultural Science
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• 제43권3호
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• pp.360-368
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• 2016

A more efficient use of nutrients can benefit both farmers and water quality. To propose an establishment scheme for official standards for liquid fertilizer from swine manure slurry, we evaluated previous and present data related to swine manure as well as analyzed 101 swine manure samples collected from 28 public livestock recycling centers throughout the nation. From these investigations, we found that the official standards for byproduct fertilizers set by the Rural Development Administration (RDA), especially for a liquid swine manure fertilizer, should be revised due to nutrient content requirements having to meet at least 0.3% content for the sum of nitrogen, phosphorus, and potassium. Otherwise, most of the swine manure cannot be utilized as a liquid fertilizer because the result of the 101 samples' analysis showed fewer than 28% of them met the minimum standard of ${\geq}0.3%$ content for the sum of nitrogen, phosphorus, and potassium, while the contents of heavy metals as indicators of toxicity met the standard requirements. Therefore, it is suggested that official standards for byproduct fertilizers set by RDA should be revised as follows: no limit for nutrient contents and addition of chloride as homogeneity. Also, NaCl should be changed to Na because NaCl cannot be analyzed by instrument.

• Fashion & Textile Research Journal
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• 제1권3호
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• pp.288-295
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• 1999

This study was conducted to examine the fatigue phenomenon of mechanical properties in tencel fabrics by repeated washing & shear and tensile deformation. The obtained results are as follows. After performing repeated shear tensile deformation, RT of tencel showed higher increase rate than that of cotton and rayon, whereas its WT and EM was a smaller decrease rate than that of them. This means that tencel's resistance to tensile deformation was the greatest. In the repeated washing and shear tensile deformation, tencel's 2HB, 2HG and 2HG5 showed a remarkable increase rate. In terms of deformation frequency, the greatest change rate appeared at the time of 1000 cycles of repeated shear tensile deformation and 15 times of repeated washing. In the hand value and THV, KOSHI showed a higher increase rate for tencel than for cotton and rayon in both repeated washing and shear tensile deformation, and NUMERI showed a higher increase rate. In the THV the change rate of rayon and cotton could be rarely seen but for tencel, it decreased. tencel's change rate of thermal insulation value by materials was 1.08%, and it increased as the washing frequency increased, compared to the grey fabrics, whereas the change rates of cotton and rayon were 0.74% and 0.22%, respectively. The qmax decreased in the order of cotton>tencel>rayon as the washing frequency increased.

• Journal of The Korean Association of Information Education
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• 제22권3호
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• pp.297-305
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• 2018

Physical computing is the concept of expanding computing to humans, environments, and objects. It draws attention as a programming learning medium based on physical outputs in integration of hardware and software. This study developed a programming learning model based on interactive prototyping using the characteristics of physical computing with a high degree of technical freedom and analyzed its learning effect in an experiment. To examine the effect of the experimental treatment, this researcher divided fifty nine 5th-grade elementary students into an experimental group and into a control group. the interactive prototyping programming learning model was applied to the experimental group, and a linear sequential programming learning model was applied to the control group. Information Science Creative Personality Test was conducted before and after the experimental treatment. Analysis of Covariance was conducted with the pre-test scores of the two groups. As a result, it was proved that there was the effect of learning at the significance level of .05. It indicates that the physical computing based interactive prototyping programming learning model is applicable to the programming learning for 5th-grade elementary students.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제29권4호
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• pp.175-184
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• 2017

With the improvement of living standards, the ventilation for the mitigation of indoor or outdoor air-pollution problems has recently attracted a lot of attention. Consequently, the ventilation for the supply of outdoor fresh air into a room is treated as an important building-design factor. The ventilation is generally divided into the forced and natural types; here, the former can control the ventilation rate by using mechanical devices, but it has the disadvantages of the equipment costs, maintenance costs, and noise generation, while the latter is applied to most workshops due to the absence of noise and the low installation and maintenance costs. In this experimental study, the ventilation performance of a typical rotating-type natural ventilator, which is called a "wind turbine," was investigated with the outdoor-wind velocity and the indoor/outdoor-temperature difference. From the experiment results, it was confirmed that the temperature difference of $10^{\circ}C$ corresponds to the ventilation driving force with an outdoor-wind velocity of 1.0 m/s. Additionally, the intake-opening area of a building also exerts a great effect on the ventilation rates.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• 제38권5호
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• pp.415-423
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• 2020

GNSS (Global Navigation Satellite System) is mostly used for high-precise surveys due to its accuracy and efficiency. But this technique does not always fulfill the demanding accuracy in harsh operational environments such as urban canyon and forest. One of the remedies for overcoming this barrier is to compose a heterogeneous surveying network by adopting terrestrial measurements (i.e., distances and angles). Hence, this study dealt with the adjustment of heterogeneous surveying networks consisted of GNSS baseline vectors, distances, horizontal and vertical angles with a view to enhancing their accuracy and so as to derive an appropriate scheme of the measurement combination. Reviewing some technical issues of the network adjustments, the simulation, and experimental studies have been carried out, showing that the inclusion of the terrestrial measurements in the GNSS standalone overall increased the accuracy of the adjusted coordinates. Especially, if the distances, the horizontal angles, or both of them were simultaneously adjusted with GNSS baselines, the accuracy of the GNSS horizontal component was improved. Comparing the inclusion of the horizontal angles with those of the distances, the former has been more influential on accuracy than the latter even though the same number of measurements were employed in the network. On the other hand, results of the GNSS network adjustment together with the vertical angles demonstrated the enhancement of the vertical accuracy. As conclusion, this paper proposes a simultaneous adjustment of GNSS baselines and the terrestrial measurements for an effective scheme that overcomes the limitation of GNSS control surveys.

• Korean Journal of Food Science and Technology
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• 제30권6호
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• pp.1420-1425
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• 1998

Rice wines, Yakju-type, were brewed with typical raw materials plus powdered acorns, and storage qualities of the fermented wines were examined. Initial optical densities of the acorn added-rice wines were shown around 0.116 at 660 nm and then decreased to $0.06{\sim}0.075$ after 10 days storage at $4^{\circ}C$. Organic acid contents in the acorn added-rice wines were lower than that of the control: the contents were lactic, succinic, citric, malic, oxalic and fumaric acid in order; and gallic acid, a kind of tannic substances was 0.39 mg%. Peroxide values of the acorn added-rice wines were not markedly changed for 9 days, remaining as low as $2{\sim}3\;meq\;kg^{-1}$ lard of lard, but that of the control was increased to $265\;meq\;kg^{-1}$ lard. As the results of clarity, acidity and antioxidation, the acorn added-rice wines appeared to be preservable, owing to tannic substances extracted from acorn powder.