• Progress in Medical Physics
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• v.12 no.2
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• pp.177-184
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• 2001

The goal of radiation treatment is to deliver a prescribed radiation dose to the target volume accurately while minimizing dose to normal tissues. Due to inaccurate placement of field and shielding block and patient's movement, there could be displacement errors between the planed and treatment regions. In order to verify the location of radiation treatment, we in this study developed the registration algorithm of the x-ray simulator images and portal images and quantified the inaccuracy in terms of shift, scale and rotation. The algorithm for registration of pairs of radiation fields consists of the alignment of pairs of radiation images by points matching and field displacement analysis by field boundary matching. In the first step, paired surface landmarks are matched to calculate the transformation parameters (scale, rotation and shift) using the corresponding line pairs which are created by connecting two landmarks of each image. In the next step, portal field boundary is extracted and then the two field boundaries are matched by the $\rho$-$\theta$ technique. Applying the phantom portal images, detection errors were calculated to be less than 2mm in translation, 1$^{\circ}$ in rotation and 1% in scale. In conclusion, we quantitatively analyzed the displacement error of x-ray simulator images and portal images. The present results could contribute to the study of the radiation treatment verification.

• Journal of Biosystems Engineering
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• v.33 no.2
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• pp.83-93
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• 2008

In order to save labor and cost, direct seeding has been considered as an important alternative to the machine transplanting in rice cultivation. Current direct seeding machines for rice in Korea drill irregularly under various operating conditions. This study was conducted to develope a precision seeder which enables the accurate, even-spaced in row placement of rice seeds at uniform depths of 3-4 cm on dry paddy. Design, construction and performance evaluation of the precision seeder were carried out. The tractor rear-mounted type 8-rows precision seeder which performs seeding in addition to fertilizing, ditching, and rotary tilling works on dry paddy was developed. Main components of the seeder were ditcher and leveller, rotary tiller, powered roller type furrow opener, seeding device, powered roller type furrow covering and firming device, hydraulic unit, seeding speed control system, power transmission system, hitch and frame. Ditching, furrow opening, and seed covering and firming performances were good and seeding depths of 2-4 cm could be maintained. Planting accuracies and planting precisions were within 13.6%, and 31.2%, respectively, for planting space of 15 cm, and seeding velocity of 0.5 m/s. These mean variations of average planting space were within 2.1 cm, and 90% of seeds in a hill were seeded within 4.7 cm of hill length, respectively. Error ratios between setting planting space and measured average planting space were shown within 6.7%. Therefore the seeder showed good planting performance up to seeding velocity of 0.5 m/s in field tests. And field capacity of the seeder was about 0.28 ha/hour.

• KIEAE Journal
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• v.12 no.4
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• pp.77-82
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• 2012

This study conducted the experiment of reduction of Volatile Organic Compounds(VOCs) and Formaldehyde concentration by Native plants, Fatsia japonica and Ardisia pusilla. The two plants are advantageous in that they are highly available as they grow wild, and being easy to get. Fatsia japonica is a plant of its wide and large leaf diverged 7 or 8 parts, which is thought to have a high effect of air purification. Ardisia pusilla has a smaller leaf than Fatsia japonica, which is characterized by more leaves and beautiful. Field measurements were performed using Fatsia japonica and Ardisia pusilla which were verified as air-purifying plants in Korea. The effect of reducing the concentration of VOCs and Formaldehyde by plant studied in a full scale mock-up model. The dimensions of the two models were equal. The concentration of Benzene, Toluene, Ethylbenzene, Xylene, Stylene, Formaldehyde were monitored, since they were known as most toxic materials. The concentration of VOCs was monitored three hours after the plants were placed and three days after the plants were placed. Field measurements were performed in models where the plants were placed and were not. As a result, they had all an effect of reducing pollution. In all cases of experiment of planting and growing volume, the more planting volume, the more excellent the effect. Toluene was more effective in Fatsia japonica and Ardisia pusilla planted, Formaldehyde was more effective in Fatsia japonica planted respectively. In planting and growing and placing experiment, the placement at sunny spot was more effective than that at scattered growing. When Fatsia japonica was placed at sunny spot, the reduction effect of Formaldehyde was the most excellent, and when Ardisia pusilla was placed at sunny spot, the reduction effect of Toluene was the most effective.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.3
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• pp.360-368
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• 2010

A SCR catalytic filter system is used for reducing $NO_x$ and soot emissions simultaneously from diesel combustors. The amount of ammonia (as a reducing agent) must be controlled with the amount of $NO_x$ to obtain an optimal $NO_x$ conversion. Hence, gas mixing between ammonia and exhaust gases is vital to ensure that the SCR catalyst is optimally used. If ammonia mass distribution is not uniform, slip potential will occur in rich concentration areas. At lean areas, on the other hand, the catalyst is not fully active. The better mixing is indicated by the higher uniformity of ammonia mass distribution which is necessary to be considered in SCR catalytic filter system. The ammonia mass distributions are depended on the flow field of fluids. In this study, the velocity field of gaseous flow is investigated to characterize the transport of ammonia in SCR catalytic filter system. The influence of different injection placements on the ammonia mass distribution is also discussed. The results show that the ammonia mass distribution is more uniform for the injector directed radially perpendicular to the main flow of inlet at the gravitational direction than that at the side wall for both laminar (Re = 640) and turbulent flows (Re = 4255). It is also found that the mixing index decreases as increasing the heating temperature in the case of ammonia injected at the side wall.

• Journal of Soil and Groundwater Environment
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• v.8 no.4
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• pp.12-20
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• 2003

This study presents a mathematical model for simulating the fate and transport of a reactive organic contaminant, TCE, degraded by cometabolism in dual-porosity soils during the installation of in situ biobarrier. To investigate the effect of dual-porosity on transport and biodegradation of organic hydrocarbons, a bimodal approach was incorporated into the model. Modified Monod kinetics and a microcolony concept were employed to represent the effects of biodegrading microbes on the transport and biodegradation of an organic contaminant. The effect of permeability reduction in biobarrier due to biomass accumulation on the flow field were examined in the simulation of a hypothetical field-scale in situ bioaugmentation. Simulation results indicate that the presence of the immobile region can decrease the bioavailability of biodegradable contaminants and that the placement of microbes and nutrients injection wells should be considered for an effective installation of biobarrier during in situ bioaugmentation scheme.

• Journal of Korean Society of Rural Planning
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• v.21 no.3
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• pp.131-144
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• 2015

With a view to creating beautiful farm villages, this study aims to exploit space syntax and thereby establish a systematic plan for refurbishing common farming facilities in farm villages by expanding a remodeling plan that has so far been focused on farm houses to cover different villages as well as in spatial scope. For this purpose, the study has extracted a system of categories for common ownership facilities in farm villages and applicable elements needed for collaboration in the space of joint production by performing a comprehensive analysis of related literature for the purpose of researching the distribution of common farming facilities. Based on such categorization of applicable elements, the study conducted a field survey of the four types of farm villages such as suburban area (Hwaseong), inland farming-centered area (Jeungpyeong), coastal & plain area (Goheung), and mid-mountain area (Gangneung), through group discussions by participating researchers and field pilot surveys. Also, space analysis has come up with measurements based on the five criteria of integration, local integration, control, connectivity, and spatial depth. And a plan for type-specific remodelling of common farming facilities has been drawn up through standardization based on the values in integration for different villages and spatial depth for common farming facilities. The significance of the current study consists in identifying how the location of common farming facilities influences the characteristics of different villages in terms of spatial structure and then drawing up guidelines for planning their placement.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.57-60
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• 2008

According to the recent tendency that the buildings in the downtown concerning rising land prices and efficient use of building are gradually Manhattanized mainly the grand scaled residential buildings, structure of the buildings relates to safety and so the very thick mat concrete is selected as the foundation of architectures. Because mat concretes can not be simultaneously pour in a great quantity due to the circumstance at the field, not only the questions on the unification between the concretes pour on the upper layer and the lower layer are presented but also the cracks by the internal force from the difference of hydration exothermic period are occurred because of the time lag. Thus, this study checked the efficiency to apply "The hydration heat controlling method of mass concrete for horizontal partition pouring construction" to the skyscraper sites under construction at Haiundai in Busan. After applying this method, the result of observation that the cracks by hydration heat in all over the placement surface did never be founded. Also, in case of the economic analysis that the hydration heat reduction method using super retarding agent by difference of setting time is approximately 80% cheaper than the hydration heat reduction method by pipe cooling in the construction expenses.

• Journal of the Korean Society of Safety
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• v.26 no.2
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• pp.89-98
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• 2011

The traffic accidents at a construction site, which happen due to construction vehicles' frequent access to a construction site, its subsequent conflicts with ordinary vehicles and pedestrians, and inappropriate installation & management of traffic security facilities, have not many proportions in all traffic accidents, but obviously, the accident damage is quite serious when comparing the level of the fatal per one accident. This research conducted an analysis of traffic accident injury severity using Ordered Probit Model in relation to 241 traffic accident cases that occurred caused by construction sites among the traffic accidents that took place in Seoul and Gyeoggi-do region for two years from 2006 until 2007. As a result, the significant variables enough to explain traffic accident injury severity were analyzed to be the state of road surface, linear shape of an accident spot & whether the damaging car belongs to the vehicle for construction, and whether vehicles have access to a construction site at the time of an accident. Through this, this research found out some fact as follows: first, there need to be more aggressive management of the vehicles for construction and a year-round placement of the manpower who can control vehicular access to a construction site. Second, it is necessary to get drivers to recognize the fact that there exists a construction site on the construction section which is on the border of curved roads in advance to prevent a traffic accident, helping to reduce socioeconomic loss & costs incurred by a traffic accident.

• Journal of Korean Library and Information Science Society
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• v.48 no.1
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• pp.43-75
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• 2017

In this study, Employment Status and Environment of Librarian, to investigate the employment prospect survey was conducted to the subjects of a librarian. The results of this study are as follows. First of all, employment environment of the library site base on the cognitive survey was showed that low wages, unstable jobs, difficulty in work due to staff placement that does not match majors, disagreement with the boss, self-regard as a librarian, excessive workload, a poor work environment etc. Second, the field workers preferred cultural program related electronic information organisation and service as the contents to be added to the curriculum of the library information department of the university. Third, the employment environment of irregular workers is characterised by high competition, low wages, high turnover number, and excessive workload. Fourth, The biggest problem when preparing for employment was the lack of employment information. Therefore, various improvement measures based on the results of the above studies are required, especially, construction of employment information system, Introduction of the field - based curriculum, specific employment conditions are required when hiring.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.4
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• pp.519-527
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• 2005

Statement of problem : There are many articles that showed that the magnetism affected the bone formation around titanium implant. It means that a proper magnetism made the osseointegration improved around the implant. So after additional research on the other effect of magnetism on bone formation in implant therapy, we can conclude its possibility of clinical application on implant treatment. Purpose: The purposes of this study were to find out the intensity of magnetic field where magnetism in the titanium implant specimen inserted into the bone could affect the bone formation, and to discover the possibility of clinical application in the areas of dental implants and bone grafts. Material and method: Ten adult male rabbits(mean BW 2Kg) were used in this study. Titanium implant specimens were surgically implanted on the mesial side of the tibia of rabbits. Neodymium magnets(Magnedisc 500, Aichi Steel Corp. Japan) were placed into the implants of experimental group except control group, just after placement of the titanium implants. At 2, 4 and 8 weeks after the surgery, the animals were sacrificed, specimens were obtained and stained with Hematoxylin-Eosin for light microscopic evaluation and histomorphometric analysis. Conclusion : The results were as follows: 1. In radiographic findings, increased radiopacity downward from crestal bone was observed along the titanium implant specimen at experimental period passed by 2, 4, and 8 weeks in both control and experimental group. 2. In histoiogic findings, increased new bone formation was shown in both control and experimental group through the experiment performed for 2, 4, and 8 weeks. More new bone formation and bone remodeling were shown in experimental group. 3. In histomorphometric analysis, the bone contact ratios were 11.9% for control group and 38.5% for experimental group (p<0.05).