• Journal of Ocean Engineering and Technology
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• v.36 no.2
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• pp.132-142
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• 2022

We investigate the performance of multi-body wave energy converters (WECs). This investigation considers multiple scattering of water waves by the buoys of a WEC under the generalized mode approach. Predominantly, the effect of a WEC's configuration on its energy extraction is studied in this research. First, single-row terminator and single-column attenuator arrays of vertical cylinders have been studied. The performance of these attenuator arrays shows that the wall effect induced by the periodic buoys influences the wave propagation and energy extraction in these WECs. Further studies show that a single-row terminator array of vertical cylinders performs better than the corresponding single-column attenuator array. Subsequently, multi-row terminator arrays of vertical cylinders are investigated by conducting a parametric study. This parametric study shows that the hydrodynamic property of three resonance phenomena makes energy extraction efficiency drop down, and the magnitude of energy extracted oscillates between the resonance points in these WECs. Finally, a 4×8 terminator array of vertical cylinders is studied to determine the effect of various d_x (x-directional distance between adjacent rows) within this WEC on its performance. In particular, this study enforces at least two equal d_x values within the 4×8 terminator array of vertical cylinders. It shows that a small value of this d_x leads to better energy extraction efficiency in some of these various d_x arrays than that of a corresponding regular array with the same d_x.

• Journal of the Korean Geotechnical Society
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• v.20 no.3
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• pp.13-22
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• 2004

In case of the lateral movement accurring at soft ground where a row of piles are installed, the crown failure at external arch zone of soil arching is firstly developed, and the cap failure at wedge zone in front of piles is lastly developed. Therefore, the lateral earth pressure acting on a row of piles due to soil movement should be calculated in each condition of crown and cap failures around piles. A theoretical equation of crown failure can be proposed using a cylindrical cavity expansion theory. The theoretical equation of crown failure is mainly affected by two factors. One is related to soil properties such as internal friction angle, cohesion and horizontal pressure, and the other is related to pile factors such as diameter, installation interval. Meanwhile, the yield range of lateral earth pressure is established in the estimation of theoretical equation based on crown and cap failures around piles. The theoretical values based on crown and cap failures are compared with the experimental values. The experimental values are located in the range proposed by theoretical values. Thus, it is confirmed that the theoretical values proposed in the study are very reasonable.

• Journal of Biosystems Engineering
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• v.35 no.6
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• pp.373-379
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• 2010

This study was carried out to develop a belt pick-up type one-row soybean cutter, using physical properties and production conditions of soybeans. The prototype soybean cutter consisted of 4 parts: cutting part, conveying part, collecting part, and travelling part. The prototype soybean cutter was designed to cut soybeans planted with a row spacing of 600 mm, and at a height of 30 mm from the bed bottom using a disk saw. Through various trials with different peripheral velocities of the disk saw and forward speed of the cutter, determined ranges of the peripheral velocity of the disk saw cutting soybeans stems were greater than 18.3 m/s. Spacing between pick-up belts (clearance) was in a range of 60~90 mm so that soybeans could be picked at heights greater than 25 cm, and the size and shape of the pick-up belt were determined the conventional manual harvesting method. The optimal ratio between the forward speed of cutter and the peripheral speed of pick-up belts were from 1 to 1.2 by theoretical analysis. the pick-up belts had a $35^{\circ}$ of tilted angle and $90^{\circ}$ of twisted angle to pick up soybeans safely from the plant input to the lower end of the belts and convey soybeans to the upper end of belts nearby a container. The soybeans at the rear container were dropped down on the soybean row with an interval. The effective field capacity of the prototype soybean cutter was 0.136 ha/h, reducing the working hour by 92% when compared with the manual cutting.

• Journal of Intelligence and Information Systems
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• v.23 no.3
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• pp.95-118
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• 2017

Recent centrally the downtown area, the transaction between the row housing and multiplex housing is activated and platform services such as Zigbang and Dabang are growing. The row housing and multiplex housing is a blind spot for real estate information. Because there is a social problem, due to the change in market size and information asymmetry due to changes in demand. Also, the 5 or 25 districts used by the Seoul Metropolitan Government or the Korean Appraisal Board(hereafter, KAB) were established within the administrative boundaries and used in existing real estate studies. This is not a district classification for real estate researches because it is zoned urban planning. Based on the existing study, this study found that the city needs to reset the Seoul Metropolitan Government's spatial structure in estimating future housing prices. So, This study attempted to classify the area without spatial heterogeneity by the reflected the property price characteristics of row housing and Multiplex housing. In other words, There has been a problem that an inefficient side has arisen due to the simple division by the existing administrative district. Therefore, this study aims to cluster Seoul as a new area for more efficient real estate analysis. This study was applied to the hedonic model based on the real transactions price data of row housing and multiplex housing. And the K-Means Clustering algorithm was used to cluster the spatial structure of Seoul. In this study, data onto real transactions price of the Seoul Row housing and Multiplex Housing from January 2014 to December 2016, and the official land value of 2016 was used and it provided by Ministry of Land, Infrastructure and Transport(hereafter, MOLIT). Data preprocessing was followed by the following processing procedures: Removal of underground transaction, Price standardization per area, Removal of Real transaction case(above 5 and below -5). In this study, we analyzed data from 132,707 cases to 126,759 data through data preprocessing. The data analysis tool used the R program. After data preprocessing, data model was constructed. Priority, the K-means Clustering was performed. In addition, a regression analysis was conducted using Hedonic model and it was conducted a cosine similarity analysis. Based on the constructed data model, we clustered on the basis of the longitude and latitude of Seoul and conducted comparative analysis of existing area. The results of this study indicated that the goodness of fit of the model was above 75 % and the variables used for the Hedonic model were significant. In other words, 5 or 25 districts that is the area of the existing administrative area are divided into 16 districts. So, this study derived a clustering method of row housing and multiplex housing in Seoul using K-Means Clustering algorithm and hedonic model by the reflected the property price characteristics. Moreover, they presented academic and practical implications and presented the limitations of this study and the direction of future research. Academic implication has clustered by reflecting the property price characteristics in order to improve the problems of the areas used in the Seoul Metropolitan Government, KAB, and Existing Real Estate Research. Another academic implications are that apartments were the main study of existing real estate research, and has proposed a method of classifying area in Seoul using public information(i.e., real-data of MOLIT) of government 3.0. Practical implication is that it can be used as a basic data for real estate related research on row housing and multiplex housing. Another practical implications are that is expected the activation of row housing and multiplex housing research and, that is expected to increase the accuracy of the model of the actual transaction. The future research direction of this study involves conducting various analyses to overcome the limitations of the threshold and indicates the need for deeper research.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.69-76
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• 2012

An achieving method of highly progressive pressure gradient is presented to enhance the missile ejection system's performance by using a gas generator in the condition of preventing erosive burning. To obtain and confirm a stable burning, a ground burning test was performed to evaluate the new methods of a radial-hole and a multi-row propellant grain. The test results show that a radial-hole grain takes good effect on erosive burning and not on ejection performance. On the other hand, a multi-row grain which reduces the length-to-diameter ratio(L/D) of grain is very effective to prevent the erosive burning and to enhance the ejection performance simultaneously.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.432-439
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• 2011

An achieving method of highly progressive pressure gradient is presented to enhance the missile ejection system's performance by using a gas generator in the condition of preventing erosive burning. To obtain and confirm a stable burning, a ground burning test was performed to evaluate the new methods of a radial-hole and a multi-row propellant grain. The test results show that a radial-hole grain takes good effect on erosive burning and not on ejection performance. On the other hand, a multi-row grain which reduces the legnth-to-diameter ratio(L/D) of grain is very effective to prevent the erosive burning and to enhance the ejection performance simultaneously.

• Journal of the Korea Computer Industry Society
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• v.2 no.6
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• pp.791-802
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• 2001

In this paper, DARC(Data Radio Channel) error correction decoder for the U Subcarrier Broadcasting System is designed of using (272,190)$\times$(272,190) product code based on (272,190) shortened difference set cyclic code. This decoder has error flag of column and row direction that can store the result of the error correction of column and row direction in the block and frame structure, is designed to be of no benefit the output with majority logic determination to cancel the corrected and determined bit, and can improve by using the error correction method that no error correction of the row direction is performed, if error correction of the column direction is completely performed by error flag.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.1
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• pp.60-65
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• 1982

In order to observe the degree and response of drought-resistance and its physiological mechanism in barley and wheat seedling stage, 5 species (16 cultivars) were tested for the changes of nitrate reductase and protease activity and the accumulation of free proline, by being subjected to water stress by withholding watering for 8 days at 10 days (at the 3rd leaf stage) after emergence and by imposing water stress to the excised first leaf by polyethyleneglycol solution (osmotic potential, -20 bars) for 48 hours. The average rate of decrease of all cultivars was 42% in nitrate reductase activity and 73% in protease activity. But proline content in water stress was increased 10 folds more than that of control. The decrease4 rate of nitrate reductase activity in 5 species was in the order of wheat < rye < covered barley < naked barley < two-row barley: wheat being the lowest. The decreased rate of protease activity in 5 species was in the order of wheat > rye > two-row barley > covered barley > naked barley: wheat being the" heighest. The accumulated amount of free proline in 5 species by water stress was in the order of wheat > covered barley > rye > naked barley > two-row barley. And the increased ratio (folds) of free proline of water stress to control was in the order of rye(13) > wheat. covered barley(11) > naked barley(99) > two-row barley(7): rye being the highest. In terms of the enzymatic activity and the physiotically adaptive metabolism during the processing leading to drought-resistance, the degree of drought-resistance of 5 species to water stress at seedling stage was shown to be in the order of wheat > rye > covered barley > naked barley > two-row barley.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.3
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• pp.17-28
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• 2003

The objective of this study is to review and verify whether the functions and effect of roadside trees generally known in theory are actually realized in urban roads and how well they are performed if the function and effect are really realized. The study was conducted with a focus on air purification effect of roadside trees. The m헤r study result is as follows. First, calculation of air purification effect of roadside trees showed that it is minimal. However, 7.4 units of broad-leaved trees is necessary in order to purify $SO_2$ discharged by one passenger car and 1,803.3 trees to purify $NO_2$. Second, regarding pollutant absorption capacity, air pollutant absorption capacity increased as the number of rows planted gets higher (i.e., 2-row plantation absorbs pollutant better than I-row plantation). In particular, "2-row plantation + lower-level shrub + buffer green belt" was as eight times high as "I-row plantation" in absorption capacity. Third, out of 30 roads with over 8 lanes in 15 cities, only 33.3% or a total of ten roads in seven cities had a median strip. Out of these ten roads, nine roads were planted in a double-layer consisting forest trees, shrubs, ground plants (grass). Analysis showed that out of six tree species planted along these roads, about a half of them were weak to air pollution. Also, based on the outcome of this study, charging a "plantation due" when people purchase a new car, improving layout of roadside trees, and reinforcing plantation of air purification tree species when selecting tree species for roadside trees were proposed.

• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.73-79
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• 2008

An experimental study was conducted to investigate the effect of a tube row, a fin pitch and an inlet humidity on air-side heat and mass transfer performance of louvered fin-tube heat exchangers under wet conditions. Experimental conditions were varied by three fin pitches, two rows, two inlet relative humidities. Experimental results showed that the heat transfer performance decreased and the friction increased with the decrease of fin pitch, for 2 row heat exchanger. The effect of fin pitch on heat transfer performance was negligible with 3 row heat exchanger. The changes in relative humidity was not affected heat transfer and friction. However, the mass transfer performance was slightly decreased with the increase of relative humidity and with the decrease of fin pitch. The mass transfer performance of the louvered fin-tube heat exchanger decreased with the decrease of the fin pitch and was different according to the number of tube row.