• International Journal of Fuzzy Logic and Intelligent Systems
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• v.3 no.2
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• pp.244-250
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• 2003

In this paper, the relationship between a slave robot and the uncertain remote environment is modeled as the impedance to generate the virtual force to feed back to the operator. For the control of a tele-operated mobile robot equipped with camera, the tele-operated mobile robot take pictures of remote environment and sends the visual information back to the operator over the Internet. Because of the limitation of communication bandwidth and narrow view-angles of camera, it is not possible to watch the environment clearly, especially shadow and curved areas. To overcome this problem, the virtual force is generated according to both the distance between the obstacle and robot and the approaching velocity of the obstacle. This virtual force is transferred back to the master over the Internet and the master(two degrees of freedom joystick), which can generate force, enables a human operator to estimate the position of obstacle in the remote environment. By holding this master, in spite of limited visual information, the operator can feel the spatial sense against the remote environment. This force reflection improves the performance of a tele-operated mobile robot significantly.

• Journal of Ecology and Environment
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• v.30 no.2
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• pp.171-177
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• 2007

Korean rivers and their surrounding environments have been used excessively for rice production in the past and more recently for construction of urban areas to accomodate the rapidly increasing population. Affected Korean rivers experience dramatic fluctuations in their water levels and have faster currents compared with those in other countries. In order to restore more natural conditions in rivers experiencing such conditions, we employed a partial restoration method, which is designed to achieve physical and biological stability simultaneously. Concrete blocks were introduced to increase the river's physical stability during floods, and terra cottem, a soil enhancer, was used to reduce water loss due to intense heat. These interventions increased the river's ability to hold water and thereby promoted plant growth. This restoration method increased vegetation coverage and species diversity in treated areas, and changed the species composition in treated areas to more closely approximate that of the control site. These results suggest that this method is effective in restoring damaged habitats to more natural conditions.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.3
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• pp.223-228
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• 2009

By the typhoon "MAEMI" in 2003, a lot of marine accidents such as stranding, collision etc. occurred to the vessels at anchor in "JINHAE MAN" which was considered one of the most safe sheltering anchorage in Korea. These accidents resulted from the dragging of anchor by the strong winds. It needs to compare the external forces with the holding powers of anchors to estimate if the anchor will be dragged or not. However, the calculation of the force by the wind on the ship, in particular, on the wind pressure area which changes by the swinging of her bow is not yet set on a thesis. Therefore, this paper verified that how many times the front wind pressure area should be applied to calculate the force by the wind on the ship at anchor by comparing and analyzing the numerical calculation with, the actual ship's data which was really dragged by the strong wind.

• 한국사회복지학회:학술대회논문집
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• 2004.04a
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• pp.705-731
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• 2004

This study is to be used for research material for pastoral counseling, by analyzing grounded-theoretically how substance abusers' awareness of self and experience of relations affects problems in abusing drugs. The subject of this study was chosen as 9 prisoners who were able to participate in group counseling, among those who were in prison for substance abuse and had more than 6 months of penal servitude left. In addition, in order to indicate counseling research methods through this study, 12 group counselings were carried out during October 24th. 2002 and February 14th. 2003 and verbatim were written out to be used as original material. After the research material was analyzed, they could be categorized into 60 concepts on the whole from 'conflict' and 'constraining thinking' to 'rationalization' and 'avoidance'. When these concepts were organized into groups of similarity, there were all together 20 categories. From this study, it can be found that substance abusers had "problems about self" and "problems about relations". The factor which affected their use of drugs was the area of relations, where as henceforth their use of drugs, the situation in which they could not escape from the use of substances was affected by problems within the area of self. When facing such problems as substance abuse, the pastoral counselor must create a holding environment through counseling, and perform good enough mothering by being insightful and providing active support on the problem. They must also help one's growth into "an empathizing self", "an accepting self", "a trusting self", "a hopeful self", who can empathize, accept, trust and hope, through experience in separation from the problem, conversion, meta-communication, self-rumination, relations and inspiration of hope. Likewise, the church must be able to act as a "place of growth and skill" which aids in the forming of relations and helps to be aware of self through experience in, and understanding of, relations.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.1
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• pp.49-55
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• 2009

Typhoons are usually influencing at least 3 or 4 times per year in Korean peninsula and they accompanied with strong winds and heavy rains and then brought tremendous loss of properties and lives. Especially typhoon "MAEMI" resulted in a lot of marine accidents of vessels such as sinking, stranding, collision etc. at anchoring or on berthing in pier. If the typhoon comes up to expected area influencing the incidents, the vessel tries to escape from the route of typhoon or anchor in sheltering anchorage. However, consideration of the anchoring or judgement of ship's safety against strong winds is decided only by the experience of operators without detail evaluation of the safety. Therefore, this paper evaluated the safety of T.S. HANBADA by comparing the external forces with the holding powers. Furthermore, based on this evaluation, the anchoring manual was produced for the maximum endurable wind velocity, the general precautions and the actions taken on the ship with steps.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.309-316
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• 2017

In this paper, numerical modeling is conducted to analyze the tension of an anchor line by varying the size and drag coefficient of a buoy when the trapnet is influenced by the wave and the current simultaneously. A mass-spring model was used to analyze the behavior of trapnet underwater under the influence of waves and current. In the simulation of numerical model, wave height of 3, 4, 5 and 6 m, a period of 4.4 s, and the flow speed of 0.7 m/s were used for the wave and current condition. The drag coefficients of buoy were 0.8, 0.4 and 0.2, respectively. The size of buoy was 100, 50 and 25% based on the cylindrical buoy ($0.0311m^3$) used for swimming crab trap. The drag coefficient of the trapnet, the main model for numerical analysis, was obtained by a circular water channel experiment using a 6-component load cell. As a result of the simulation, the tension of the anchor line decreased proportional to buoy's drag coefficient and size; the higher the wave height, the greater the decrease rate of the tension. When the buoy drag coefficient and size decreased to one fourth, the tension of the anchor line decreased to a half and the tension of the anchor line was lower than the holding power of the anchor even at 6 m of wave height. Therefore, reducing the buoy drag coefficient and size appropriately reduces the trapnet load from the wave, which also reduces the possibility of trapnet loss.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.5
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• pp.1390-1411
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• 2024

Underwater Wireless Sensors Networks (UWSNs) are deployed in remotely monitored environment such as water level monitoring, ocean current identification, oil detection, habitat monitoring and numerous military applications. Providing scalable and efficient routing is very challenging in UWSNs due to the harsh underwater environment. The biggest difficulties are the nodes inherent movement due to water current, long delay in data transmission, low bandwidth of the acoustic signal, high error rate and energy scarcity in battery powered nodes. Many routing protocols have been proposed to solve the aforementioned problems. There are three broad categories of routing protocols namely depth based, energy based and vector-based routing. Vector Based Forwarding protocols perform routing through virtual pipeline by defining their radius which give proper direction to packets communication. We proposed a routing protocol termed as Path-Oriented Energy Scaled Expanded Vector Based Forwarding (PESEVBF). PESEVBF takes into account all parameters; holding time, the source nodes packets routing path and void holes creation on the second hop; PESEVBF not only considers the packet upward advancement but also focus on density of the forwarded nodes in terms of number of potential forwarding and suppressed nodes for path selection. Node selection in resultant holding time is based on minimum Path Factor (PF) value. Moreover, the suppressed node will be selected for packet forwarding to avoid the void holes occurrences on the second hop. Performance of PESEVBF is compared with other routing protocols using matrices such as energy consumption, packet delivery ratio, packets dropping ratio and duplicate packets creation indicating considerable performance improvement.

• Journal of Bio-Environment Control
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• v.24 no.1
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• pp.39-44
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• 2015

To improve crop productivity with optimal water management in soilless culture, the information of physical characteristics of the root medium including water behavior should be required. The objectives of this study were to analyze the physical characteristics including hydraulic properties of the root media commercially used and to analyze the relationships between actual moisture content and measured one by FDR sensor. The weight of the medium was measured by load cell for calculating the actual moisture content. The accuracy of the moisture content measured by FDR sensor was obtained by comparing with the actual one. The water holding capacity of the coir was lower than those of the rockwool due to the features of large and rough particles of the coir. The moisture content measured by FDR sensor showed large difference from the actual moisture contents measured by loadcell, indicating that the calibration of FDR sensor is needed before starting measurement. The optimum range of moisture content for irrigation control was narrow in the coir than the rockwool due to the lower water holding capacity and rehydration capability of the coir. The results of this study can be useful in establishing adequate irrigation strategies in the soilless culture.

• Korean Journal of Community Nutrition
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• v.12 no.5
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• pp.617-629
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• 2007

To ensure the microbiological safety of food items prepared after cooking process, this study was aimed to identify the hazards related with cooked foods donated to foodbanks through quantitative microbial analysis. Five foodbanks located in Incheon and Gyeonggi area among government-dominant foodbanks were surveyed from February to June, 2007. Manager, recipient, donator, type and quantity of donated foot and facility and equipment were examined for the general characteristics of foodbank. The time and temperature of food md environment were measured at steps from after-production to before-distribution, and the microbial analysis was performed mainly with indicator organism and major pathogens. The amount of cooked foods donated to each foodbank was about 20 to 30 servings and consisted of 80% of total donated foods. Only three foodbanks had separate offices for foodbank operation and four institutions had at least one temperature-controlled vehicle. The flow of donated foods was gone through the steps; production, meal service and holding at donator, collection by foodbank, transport (or holding after transport) and distribution to recipients. It took about 3.8 to 6.5 hours at room temperature from after-production to before-distribution. Only aerobic plate counts (APC) and coliforms were found in microbial analysis. The APC after production were relatively high in $8.2{\times}10^5,\;7.4{\times}10^5,\;6.9{\times}10^5$ and $4.2{\times}10^5 CFU/g$ while $2.8{\times}10^6, \;9.4{\times}10^5,\;1.0{\times}10^6$ and $5.4{\times}10^5CFU/g$ before distribution in mixed Pimpinella brachycarpa, mixed chard mixed amaranth and mixed spinach, respectively. The levels of coliforms in mixed chard and mixed spinach were complied with the standards of the Ministry of Education and Human Resources Management The level of APC in boiled pork was increased from $< 1.0{\times}10 CFU/g$ to $4.0{\times}10^2 CFU/g$. One of delivery vessels was shown $6.2{\times}10^3 CFU/100 cm^2$ in APC, which was over the standards for environment. One of serving tables also showed the high level of $1.2{\times}10^3 CFU/100 cm^2$ in APC and $6.6{\times}10^2 CFU/100 cm^2$ in coliforms. These results suggest the sanitary management of holding at donator and the time-temperature control are key factors to ensure the safety of cooked foods donated to foodbank.

• Journal of the Korea Society of Computer and Information
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• v.9 no.2
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• pp.57-62
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• 2004

In these days, application systems for processing information using database is increasing. Enterprises holding a lot of data do not possess needed data but instead include unrelated, independent and individual data. As a result, it only contains disparate data. Disparate data is ambiguous and it does not support current integrated information. In response to the above problems, data warehouse may provide a solution. Building a data warehouse needs a systematic design because of its complexity. This paper describes an efficient design methodology using visual environment for data warehouse to cope with the requirements of end users. Also, the system is able to process existential SQL query.