• Journal of the Korean Physical Society
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• v.73 no.9
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• pp.1362-1369
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• 2018

A method aimed at improving the beam-wave interaction efficiency by changing the coupling slot configuration has been proposed in the study of extended interaction oscillators (EIOs). The dispersion characteristics, coupling coefficient and interaction impedance of the high-frequency structure based on different types of coupling slots have been investigated. Four types of coupled cavity structures with different layouts of the coupling slots have been compared to improve the beam-wave interaction efficiency, so as to analyze the beam-wave interaction and practical applications. In order to determine the improvement of the coupling slot to a coupled cavity circuit in an EIO, we designed four nine-gap EIOs based on the coupled cavity structure with different coupling slot configurations. With different operating frequencies and voltages takes into consideration, beam voltages from 27 to 33 kV have been simulated to achieve the best beam-wave interaction efficiency so that the EIOs are able to work in the $2{\pi}$ mode. The influence of the Rb and the ds on the output power is also taken into consideration. The Rb is the radius of the electron beam, and the ds is the width of the coupling slot. The simulation results indicate that a single-slot-type EIO has the best beam-wave interaction efficiency. Its maximum output power is 2.8 kW and the efficiency is 18% when the operating voltage is 31 kV and electric current is 0.5 A. The output powers of these four EIOs that were designed for comparison are not less than 1.7 kW. The improved coupling-slot configurations enables the extended interaction oscillator to meet the different engineering requirements better.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.292-299
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• 2022

This study was conducted to analyze physical and chemical properties of horticultural substrates and response of hydroponically grown two cultivars of 'Namcheon' and 'Somirang' perilla by four different substrates: coir (chip:dust = 5:5), perlite, granular rockwool, and commercial mixed substrate (cocopeat:peatmoss:vermiculite:perlite: zeolite = 50:25:10:10:5). There were no significant differences in EC and pH according to substrates. Container capacity was the greatest in granular rockwool, and it showed appropriate levels in mixed substrate and coir. Air space was higher in coir and perlite than the other treatments. Bulky density reached a proper standard in all substrates excepting coir. The leaf length and width of 'Namcheon' indicated the most in mixed substrate, though the value of 'Somirang'was greatest in coir substrate. The leaf weight of both cultivars was highest in mixed substrate, and relatively low in coir and perlite. The total yield of leaves was separated by two groups: higher group, which are mixed substrate and granular rockwool, and lower group, which are coir and perlite. There was a large gap by 28% between these two groups. Therefore, this study suggests that substrates with high water holding capacity such as mixed substrate or granular rockwool are most suitable for the hydroponic cultivation of perilla, which require sufficient moisture supply to the root zone.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.383-394
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• 2023

In Korea, the U.S. Tier-4 Final emission standards have been applied to agricultural machinery since 2015. This study was conducted to analyze the emission characteristics of agricultural tractors during plow tillage operations using PEMS (portable emissions measurement systems). The tractor working speed was set as M2 (5.95 km/h) and M3 (7.60 km/h), which was the most used gear stage during plow tillage operation. An engine idling test was conducted before the plow tillage operation was conducted because the level of emissions differed depending on the temperature of the engine (cold and hot states). The estimated level of emissions for the regular area (660 m²), which was the typical area of cultivation, was based on an implement width of 2.15 m and distance from the work area of 2.2 m. As a result, average emission of CO (carbon monoxide), THC (total hydrocarbons), NOx (nitric oxides), and PM (particulate matter) were approximately 6.17×10-2, 3.36×10^-4, 2.01×10^-4, and 6.85×10^-6 g/s, respectively. Based on the regular area, the total emission of CO, THC, NOx, and PM was 2.62, 3.76×10^-2, 1.63, and 2.59×10^-4 g, respectively. The results of total emission during plow tillage were compared to Tier 4 emission regulation limits. Tier 4 emission regulation limits means maximum value of the emission per consumption power (g/kWh), calculated as ratio of the emission and consumption power. Therefore, the total emission was converted to the emission per power using the rated power of the tractor. The emission per power was found to be satisfied below Tier 4 emission regulation limits for each emission gas. It is necessary to measure data by applying various test modes in the future and utilize them to calculate emission because the emission depends on various variables such as measurement environment and test mode.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.4
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• pp.16-21
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• 2017

In this paper, a Small-sized and planer resonator design of Magnetic Resonance - Wireless Power Transfer(MR-WPT) were proposed for practical applications of mobile devices, such as a laptop, a smart-phone and a tablet pc. The proposed MR-WPT system were based on four coil MR-WPT and designed as a transmitter part (Tx) and a receiver part (Rx) both are the same shape with the same loop and resonator. There are four different spiral coil type of resonators with variable of line length, width, gap and turns in $50mm{\times}50mm$ size. The both of top and bottom side of substrate(acrylic; ${\varepsilon}_r=2.56$, tan ${\delta}=0.008$) ere used to generate high inductance and capacitance in limited small volume. Loops were designed on the same plane of resonator to reduce their volume, and there are three different size. The proposed MR-WPT system were fabricated with two acrylic substrate plane of Tx and Rx each, the Rx and Tx loops and resonators were fabricated of copper sheets. There are 12 combinations of 3 loops and 4 resonators, each combination were measured to calculate transfer efficiency and resonance frequency in transfer distance from 1cm to 5cm. The measured results, the highest transfer efficiency was about 70%, and average transfer efficiency was 40%, on the resonance frequency was about 6.78 MHz, which is standard band by A4WP. We proposed small-sized and planer resonator of MR-WPT and showed possibility of mobile applications for small devices.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.191-198
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• 2009

Statement of problem: Ceramics have been important materials for the restoration of teeth. The demands of patients for tooth-colored restorations and the availability of various dental ceramics has driven the increased use of new types of dental ceramic materials. Improved physical properties of theses materials have expanded its use even in posterior crowns and fixed partial dentures. However, ceramic still has limitation such as low loading capability. This is critical for long-span bridge, because bridge is more subject to tensile force. Purpose: The wire reinforced ceramic was designed to increase the fracture resistance of ceramic restoration. The purpose of this study was to evaluate the fracture resistance of wire reinforced ceramic. Material and methods: Heat pressed ceramic(ingot No.200 : IPS Empress 2, Ivoclar Vivadent, Liechtenstein) and Ni-Cr wire(Alfa Aesar, Johnson Matthey Company, USA) of 0.41 mm diameter were used in this study. Five groups of twelve uniform sized ceramic specimens(width 4 mm, thickness 2 mm, length 15 mm) were fabricated. Each group had different wire arrangement. Wireless ceramic was used as control group. The experimental groups were divided according to wire number and position. One, two and three strands of wires were positioned on the longitudinal axis of specimen. In another experimental group, three strands of wires positioned on the longitudinal axis and five strands of wires positioned on the transverse axis. Three-point bending test was done with universal testing machine(Z020, Zwick, Germany) to compare the flexural modulus, flexural strength, strain at fracture and fracture toughness of each group. Fractured ceramic specimens were cross-sectioned with caborundum disc and grinded with sandpaper to observe interface between ceramic and Ni-Cr wire. The interface between ceramic and Ni-Cr wire was analyzed with scanning electron microscope(JSM-6360, JEOL, Japan) under platinum coating. Results: The results obtained were as follows: 1. The average and standard deviation in flexural modulus, flexural strength and fracture toughness showed no statistical differences between control and experimental groups. However, strain was significantly increased in wire inserted ceramics(P<.001). 2. Control group showed wedge fracture aspects across specimen, while experimental groups showed cracks across specimen. 3. Scanning electron microscopic image of cross-sectioned and longitudinally-sectioned specimens showed no gap at the interface between ceramic and Ni-Cr wire. Conclusion: The results of this study showed that wire inserted ceramics have a high strain characteristic. However, wire inserted ceramics was not enough to use at posterior area of mouth in relation to flexural modulus and flexural strength. Therefore, we need further studies.

• Journal of the Korean Institute of Landscape Architecture
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• v.46 no.3
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• pp.58-69
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• 2018

This study investigated root damage characteristics and correlations between roadside trees and street furniture through the investigation of the root damage conditions and the current status of roadside trees and street furniture in Seo-gu, Daejeon City where the occurrence of pavement uplift is frequent. The study area was divided into six areas by species of trees as Metasequoia glyptostroboides and Platanus occidentalis focusing on the streets that were installed with trees chest height and 8cm round planted at the time of the development of the Dunsan-dong Housing Site Development in Seo-gu, Daejeon metropolitan city (1990~1994). The damage rate of roadside protection frames (95.3%) was higher than that of curbstones (19.7%) at the study site. Streets without a protective frame were more likely to have damaged pavement. In addition, the frequency of breakage of protective frames was lowered when a drinking water area was increased to more than a certain level. The frequency of the type of uplift in the sidewalk pavement surfaces is in the order of tail type > mounding type > irregular type, and the frequency of the uplift direction is the highest in Direction 1 ($0{\sim}44^{\circ}C$), Direction 2 ($45{\sim}89^{\circ}$), and Direction 3 ($95{\sim}134^{\circ}$) when $180^{\circ}$ of the street direction is based on $90^{\circ}$ parallel to the curbstone. The uplift length is about 31~60cm and it is most often at a height of 3~6cm. When comparing the results of uplift deformation, Metasequoia glyptostroboides was found to be higher than the deformation of Platanus occidentalis. In addition, it can be seen that the larger the length, width and height of the ridge, the larger the deformation becomes. The relationship between the diameter at breast height, the dimension of the pavement width, the frequency of the ridge phenomenon and the deformation amount is not necessarily proportional, and there seems to be a gap due to external factors such as soil humidity and planting base. Therefore there is a need for a multi-directional approach in reducing uplift.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.1
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• pp.27-32
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• 1994

These studies were Conducted to survey cultivation methods, and to analyze soil chemical properties for stable production of Aralia continentalis K., a promising medicinal crop, in the main producting districts. Aralia continentalis K. was cultivated with planting budstocks in distances of $90cm{\times}60cm$ for 3~4 years in the same field, and application rates were N 10~31 kg/10a and P, K 8~17/10a using inorganic fertilizer, that is compound fertilizer(21-17-17) for basal dressings and urea for topdressings. Most of all, the soil surveyed was coarse loamy class which was well drained and soil depth is 50~150cm in the valleys. Soil pH was low, and content of organic matters and av. $P_2O_5$ was abundant but that of exchangeable cation such as Ca, Mg, K was deficient. The relationship between growth characteristics and weight of fresh root was positive correlation in the order of No. of root, stem width, No. of node and branch, plant height and root width. On the path coefficiant analysis, the relationship between content of soil K, Ca and root yield was more apparent than other chemical properties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.2
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• pp.203-209
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• 2009

Yield monitoring is one of a precision agriculture technology that is used most widely. It is spatial variability analysis of yield information that should be attained with yield monitoring system development. This experiment was conducted to evaluate spatial variability of yield and grain moisture content in rice paddy field, and their relationships to rice productivity. It is necessary to minimize sampling interval for accurate yield map making or to control cutting width of rice combine. Considering small rice plots such as $0.2{\sim}0.4$ ha, optimum size of sampling plot was below 15 m more than 5 m in with and length. In variable rate treatment field, average yield was similar, but yield variation was reduced than conventional field. Gap of yield by another plot in same field was bigger than half of average yield than yield variation was significantly big. Therefore yield measuring flow sensor must be able to measure at least 300 kg/10a more than 1000 kg/10a. Variation of moisture content in same field was not big and spatial dependance did not appear greatly. But, variation between different field is appeared difference according to weather circumstance before harvesting. Change of spatial dependence of yield was not big, because of field variation of moisture content is not big.

• Journal of Intelligence and Information Systems
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• v.23 no.4
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• pp.57-76
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• 2017

Recently, consumer needs are diversifying as information technologies are evolving rapidly. A lot of IT devices such as smart phones and tablet PCs are launching following the trend of information technology. While IT devices focused on the technical advance and improvement a few years ago, the situation is changed now. There is no difference in functional aspects, so companies are trying to differentiate IT devices in terms of appearance design. Consumers also consider design as being a more important factor in the decision-making of smart phones. Smart phones have become a fashion items, revealing consumers' own characteristics and personality. As the design and appearance of the smartphone become important things, it is necessary to examine consumer values from the design and appearance of IT devices. Furthermore, it is crucial to clarify the mechanisms of consumers' design evaluation and develop the design evaluation model based on the mechanism. Since the influence of design gets continuously strong, various and many studies related to design were carried out. These studies can classify three main streams. The first stream focuses on the role of design from the perspective of marketing and communication. The second one is the studies to find out an effective and appealing design from the perspective of industrial design. The last one is to examine the consumer values created by a product design, which means consumers' perception or feeling when they look and feel it. These numerous studies somewhat have dealt with consumer values, but they do not include product attributes, or do not cover the whole process and mechanism from product attributes to consumer values. In this study, we try to develop the holistic design evaluation model based on consumer values based on three-step approach from product attributes, perceived attributes, to consumer values. Product attributes means the real and physical characteristics each smart phone has. They consist of bezel, length, width, thickness, weight and curvature. Perceived attributes are derived from consumers' perception on product attributes. We consider perceived size of device, perceived size of display, perceived thickness, perceived weight, perceived bezel (top - bottom / left - right side), perceived curvature of edge, perceived curvature of back side, gap of each part, perceived gloss and perceived screen ratio. They are factorized into six clusters named as 'Size,' 'Slimness,' 'No-Frame,' 'Roundness,' 'Screen Ratio,' and 'Looseness.' We conducted qualitative research to find out consumer values, which are categorized into two: look and feel values. We identified the values named as 'Silhouette,' 'Neatness,' 'Attractiveness,' 'Polishing,' 'Innovativeness,' 'Professionalism,' 'Intellectualness,' 'Individuality,' and 'Distinctiveness' in terms of look values. Also, we identifies 'Stability,' 'Comfortableness,' 'Grip,' 'Solidity,' 'Non-fragility,' and 'Smoothness' in terms of feel values. They are factorized into five key values: 'Sleek Value,' 'Professional Value,' 'Unique Value,' 'Comfortable Value,' and 'Solid Value.' Finally, we developed the holistic design evaluation model by analyzing each relationship from product attributes, perceived attributes, to consumer values. This study has several theoretical and practical contributions. First, we found consumer values in terms of design evaluation and implicit chain relationship from the objective and physical characteristics to the subjective and mental evaluation. That is, the model explains the mechanism of design evaluation in consumer minds. Second, we suggest a general design evaluation process from product attributes, perceived attributes to consumer values. It is an adaptable methodology not only smart phone but also other IT products. Practically, this model can support the decision-making when companies initiative new product development. It can help product designers focus on their capacities with limited resources. Moreover, if its model combined with machine learning collecting consumers' purchasing data, most preferred values, sales data, etc., it will be able to evolve intelligent design decision support system.

• Korean Journal of Ecology and Environment
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• v.38 no.1 s.110
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• pp.83-94
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• 2005

The objective of the study was to elucidate early life history of Rhinogobius brunneus, based on laboratory observations and field works, along with its courtship and spawning behaviors. The male and female fish matured were sampled for the lab experiments from Gap-Stream, which is one of the tributaries of Geum-River, Korea. The spawning behaviors and courtship of matured adults had a typical pattern; matured males of Rhinogobius brunneus built up spawning nests and had their own territory before the spawning, and the behavior then triggered the egg spawning of female with active courtship. The females attached elliptic egg mass as a single layer, on the stones below the spawning nest. After the spawning, the egg mass was guarded by males only until the hatching. The size of egg fertilized, measured by microscope was about 1.5${\pm}$0.1mm in length and 0.7${\pm}$0.1 mm in the egg's width. According to the lab experiments conducted under four temperature regime, the lapsed time for the hatching was shortened as temperatures increased in the treatments. On the contrary to the hatching time, the average length of newly hatched larvae showed a reverse relation with water temperature. The larvae, considered a final stage of the early life history was about 3.6 mm in total length for water temperature of $18^{\circ}C$, whereas they were between 3.1 mm and 3.2 mm for over $25^{\circ}C$. This indicates that higher water temperature may decrease the growth rate in the early life history. These results may provide valuable information for the population conservation and ecosystem protection under accelerated water pollution and habitat degradations in Korea.