• Journal of the Korean Institute of Landscape Architecture
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• v.25 no.1
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• pp.112-123
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• 1997

This study investigated the effect of high-rise buildings on the preference for rural landscapes. The study site was a Seoul suburban, Yong-in, which showed typical scenes of rural development. Slides used in the study were taken in Young-in along the national road 45(north-south) and national road 42(east-west). Forty slides reflecting typical characters of Young-in were selected. Among them, ten slides which were selected through factor analysis based on “ruralits”score were used as original slides. They represent ten landscape types. The simulation of original slides was based on the following aspects: a observation distance. number of buildings and landscape types. The preferences for the landscapes were tested by 200 respondents on 40 slides: Distance(2) ${\times}$ Landscape type(10) = 20 slides, Number of buildings(2) ${\times}$ Landscape type(10) = 20 slides. The following results are found: 1) When high-rise buildings are introduced into rural scenes, there are some vulnerable landscape types: the landscape with high “rurality”, the landscape with background skyline and the focal landscape. 2) The observation distance affects landscape preference. The hypothesis that the nearer the distance the lower the preferences, is accepted. However, there are some exceptions in 3 landscape types. 3) The hypothesis that the more the number of buildings, the lower the preferences, is rejected. The result is quite unexpected one. When a single building is introduced in natural scene, it draws more attention as a focal point than a group of buildings, and subsequently the visual impact is stronger.

• Journal of Power System Engineering
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• v.22 no.6
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• pp.28-35
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• 2018

The large-eddy simulation (LES) was carried out to evaluate the instantaneous vector and vorticity profiles of a small-size axial fan (SSAF) at the operating point of full-flowrate. The downstream flow of the SSAF exhibits a shorter axial flow when not fully developed, especially the stronger vortex appears at the edge near the flow end. On the other hand, the downstream flow of the SSAF exhibits a longer axial flow, and the weaker vortex appears at the edge near the flow end when the flow is sufficiently developed. Moreover, in the downstream of the SSAF, a periodic and intermittent flow pattern appears at the edge showing the axial flow, and the instantaneous vorticity contour lines showing the form of a circle group are distributed at specific intervals from the downstream region of the blade tip, which is considered to be the result of the intermittency phenomenon influenced by the number of blades and the number of revolutions.

• Journal of Environmental Health Sciences
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• v.46 no.5
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• pp.588-598
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• 2020

Objectives: Human indices were developed to determine returning point of residents and damage restoration after the chemical accident Methods: To determine the returning point of residents after the chemical accident, a new concept, the standard man model was introduced as a human index, in which both H-code and its acute effects were main idea. To evaluate the applicability, a hydrogen fluoride leakage accident in Gumi was applied. The returning point were suggested as the conservative remission period of acute effects among relevant hazard effects and compared with actual returning point. The coverage of each age group were considered with reflecting average daily dose expected for actual residents. In addition, a relief-index as a social-scientific approach was reflected as well to apply the damage restoration Results: Actual returning point of residents in Gumi was 88 days; and that of standard man model suggested was 84 days. The expected amount of exposure at aged 12 or under was at least 2.35 times greater than that of this model, 40s, theoretically. However, their population ratio was less than 1%, so 99% of residents could be applied when the standard man model was applied. The relief-index was as an objective and quantitative methodology to apply the qualitative aspect. Conclusions: Although evaluated as a relatively positive result, there was a limitation such as the number of accident applied to the verification of standard man model. The relief index was also considered, but further research should be carried out to find threshold level for the relief.

• Journal of Wetlands Research
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• v.25 no.2
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• pp.75-82
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• 2023

Data for measuring the flow rate of streams are used as important basic data for the development and maintenance of water resources, and many experts are conducting research to make more accurate measurements. Especially, in Korea, monsoon rains and heavy rains are concentrated in summer due to the nature of the climate, so floods occur frequently. Therefore, it is necessary to measure the flow rate most accurately during a flood to predict and prevent flooding. Thus, the U.S. Geological Survey (USGS) introduces 1, 2, 3 point method using a flow meter as one way to measure the average flow rate. However, it is difficult to calculate the average flow rate with the existing 1, 2, 3 point method alone.This paper proposes a new 1, 2, 3 point method formula, which is more accurate, utilizing one probabilistic entropy concept. This is considered to be a highly empirical study that can supplement the limitations of existing measurement methods. Data and Flume data were used in the number of holesman to demonstrate the utility of the proposed formula. As a result of the analysis, in the case of Flume Data, the existing USGS 1 point method compared to the measured value was 7.6% on average, 8.6% on the 2 point method, and 8.1% on the 3 point method. In the case of Coleman Data, the 1 point method showed an average error rate of 5%, the 2 point method 5.6% and the 3 point method 5.3%. On the other hand, the proposed formula using the concept of entropy reduced the error rate by about 60% compared to the existing method, with the Flume Data averaging 4.7% for the 1 point method, 5.7% for the 2 point method, and 5.2% for the 3 point method. In addition, Coleman Data showed an average error of 2.5% in the 1 point method, 3.1% in the 2 point method, and 2.8% in the 3 point method, reducing the error rate by about 50% compared to the existing method.This study can calculate the average flow rate more accurately than the existing 1, 2, 3 point method, which can be useful in many ways, including future river disaster management, design and administration.

• Journal of Biosystems Engineering
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• v.35 no.3
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• pp.182-188
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• 2010

Post-Harvest processing engineering is a field that studies prevention of the quality change of agricultural products during sorting, packaging, storage, and distribution after harvested. In distribution steps, agricultural products could be damaged by physical force, it is the main reason of low quality and they lost value of commodities. This study was performed to find the vibration characteristics of the peach, and to find the extent of the damage on the peach by fatigue stress. The vibration data was obtained on expressway and the vibration characteristics of peach was used to find the damage on the peach. To analyze the vibration characteristics of peach, the resonance frequency and vibration transmissibility were measured. The resonance frequency of the peach was 167.98 Hz and the transmissibility was 4.06 at resonance point. It was 150 ~ 250 Hz that the transmissibility was more than 1. And the transmissibility in simulated test was measured. When the trasmissibility was more than 1, the range was 15 ~ 65 Hz, and when it was less than 1, the range was 65 ~ 175 Hz. When the transmissibility was about 1, the range was 5 ~ 15 Hz. The damage and the vibration cycle numbers of peaches were compared with input frequency and acceleration. More damage and less cycle number happened in 30 Hz than in 62.5 Hz. The reason was that the transmissibility of 30 Hz was higher and the vibration displacement in lower frequency was more. The more acceleration and cycle number increased, the more the bruising volume of peaches increased. The bruising volume ratio for vibration fatigue was measured according to input acceleration and cycle number. Using measured data, regression models for bruising volume ratio(BVR) was developed as a function of the acceleration(A) and cycle number(CN) as follows. BVR = a * $A^b*$ $(CN)^c$

• Journal of the korean society of oceanography
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• v.34 no.1
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• pp.22-35
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• 1999

The response of the tidal waves to friction effect is investigated in terms of deformation of Kelvin and Poincare modes, The 1st Poincare mode does not exist over the low frequency region less than the critical frequency of omega ${\omega}$${\sqrt{2f}}$, with ${\gamma}$/f=0.0, but the mode comes to exist in the presence of friction. When friction exists and its magnitude increases, the wave number increases, indicating that the wave length of the Poincare mode becomes increasingly short with increasing friction. The damping coefficient gradually increases with increasing friction over the high frequency region, but the trend is reversed over the low frequency region. In case of Kelvin wave the present study substantiates the characters of Kelvin wave examined by Mofjeld (1980) and Lee (1988). Based on the examination of frictional effects on the tidal wave propagation, the co-oscillating tides in the Yellow Sea are examined by considering both the head opening and bottom friction effects. As friction is introduced and increased in addition to partial opening at bay head, the location of the amphidromic point near the Shantung Peninsula moves more southwestward. This southwestward movement of the amphidromic point is increasingly compatible with the observed location of Ogura's or Nishida's tidal chart of the M$_2$ tide.

• Current Research on Agriculture and Life Sciences
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• v.26
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• pp.17-22
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• 2008

This research put most emphasis on setting the guidelines for improvement through character analysis of landscape ecology to cope with ecological malfunction of the woodland surrounded in cultivated areas. The results are as follows. 1) As a result of character analysis of the woodland in cultivated area in point of landscape ecology in five case sites, the size of case site 3 is the largest as $3,000m^2$ and it is shown that a colony of pine trees which is valuable in terms of ecological, scientific, historic and cultural senses. 2) As a result of analysis on expansibility of woodland in cultivated area, case site 1 is 0.25, the lowest, flexibility is 4, the highest. In order to improve ecological function in woodland, it is regarded that maintaining curve form rather than straight one. 3) As a result of analysis of morphological diversity, case site 5 shows 1.3, the highest. However, the condition of vegetation and emergence frequency of species indicates low value degree. 4) Based on the result of analysis of landscape ecological character like above, the number of guidelines for the woodland in cultivated area is three and vegetation is four.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.177-185
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• 2011

In order to reduce traffic accidents at long road sections involving high risks of traffic accidents, including tunnels, bridges or curves, the National Police Agency have decided a tentative installation and operation of an automated point-to-point speed enforcement system based on cameras at January, 2007. The first system was established at the direction to Kangreung of Dunnae Tunnel at December, 2007. Currently, the automated point-to-point speed enforcement system operates at 11 sections including eight sections on expressways and three sections on national highways. However, there have been few researches on the effects of the system upon the reduction of traffic accidents in a scientific way. To this end, this research effort was initiated to evaluate the effect of the automated point-to-point speed enforcement system on traffic safety by comparing the number of traffic accidents before and after the installation of the system using a comparison-group(C-G) method. Three-year-long traffic accident data for the expressways were collected in order to evaluate the system. As a result, the installation of the system was found to reduce traffic accidents by 49.97% in average.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.1
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• pp.66-74
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• 2018

In order to evaluate the precision degree of the blocks on the dock, the shipyards recently started to use the point cloud approaches using the 3D scanners. However, they hesitate to use it due to the limited time, cost, and elaborative effects for the post-works. Although it is somewhat traditional instead, they have still used the electro-optical wave devices which have a characteristic of having less dense point set (usually 1 point per meter) around the contact section of two blocks. This paper tried to expand the usage of point sets. Our approach can estimate the rework time to weld between the Pre-Erected(PE) Block and Erected(ER) block as well as the precision of block construction. In detail, two algorithms were applied to increase the efficiency of estimation process. The first one is K-mean clustering algorithm which is used to separate only the related contact point set from others not related with welding sections. The second one is the Concave hull algorithm which also separates the inner point of the contact section used for the delayed outfitting and stiffeners section, and constructs the concave outline of contact section as the primary objects to estimate the rework time of welding. The main purpose of this paper is that the rework cost for welding is able to be obtained easily and precisely with the defective point set. The point set on the blocks' outline are challenging to get the approximated mathematical curves, owing to the lots of orthogonal parts and lack of number of point. To solve this problems we compared the Radial based function-Multi-Layer(RBF-ML) and Akima interpolation method. Collecting the proposed methods, the paper suggested the noble point matching method for minimizing the rework time of block-welding on the dock, differently the previous approach which had paid the attention of only the degree of accuracy.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.4
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• pp.457-463
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• 2012

Cascaded H-bridge multilevel inverters shows a useful circuit configuration to increase the number of output voltage levels to obtain high quality output voltage. By applying the concept of the power of three to dc voltage sources, it can increase the number of output voltage levels effectively. To realize this concept, two approaches may be considered. One is to use independent dc voltage sources pre-scaled in the power of three, and the other is to use instantaneous dc voltage sources generated from a cascaded transformer, which has the secondary turn-ratios scaled in the power of three in sequence. A common feature in both approaches is to use the concept of the power of three for dc voltage sources, and a point of difference is whether it adopts a low frequency transformer or not, and where the transformer is located. According to the difference, application areas are limited and show different characteristics on THD of output voltages. We compare and analyze both approaches for their circuit configurations, voltage level generating method, THD characteristics of output voltage, efficiency, application areas, limitations, and other characteristics by experiments using 500 [W] prototypes when they generate a 27-level output voltage.