• Journal of Korean Society of Environmental Engineers
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• v.36 no.5
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• pp.303-310
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• 2014

This study investigated the reduction of food waste through the slurry phase decomposition in a source of food waste by microorganisms. The reactor used in the experiment was composed of both woodchip with wood material and sponges with polyurethane material as media of attached microorganisms, and food waste was mixed with a constant cycle consisted of a stirring device. During the experimental period of 100 days, the change in weight over the cumulative total amount of food waste added was reduced by 99%. Approximately, 1% of the residual food waste could be inherently recalcitrant materials (cellulose, hemicellulose, lignin, etc.) and thus was thought to be the result of the accumulation. The initial pH in wastewater generated from food waste was low with 3.3 and after 24 hours treatment this pH was increased to 5.8. The concentrations of COD, BOD, SS, salinity, TN and TP were gradually decreased. Food waste decay was proceeded by the seven species microorganisms identified and confirmed in this study, making a slurry phase and thus reducing residual food wastes. In the initial phase, the microbial population was approximately $3.3{\times}10^4$ cell/mL, and after 15 days this population was a constant with $5.1{\times}10^6$ cell/mL which means a certain stabilization for the reduction of food wastes. From these results, it can be considered that organic matter decomposition as well as the weight loss of food wastes by microorganisms is done at the same time.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.195-206
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• 1980

Fish were grown in a water recycling rearing system consisting of a filter system, of which the area is about $30\;m^2$ and the volume of filter gravels is about $15\;m^3$, 6 rearing and 2 supplementary tans about $7\;m^2$ of surface area each. The results for 180 days from April 18 to October 14,1980 are summarized as following: One rearing tank was used for main experiment stocked with an equal number, and weight of each Israeli strain and $F_1$, hybrid between this strain and Korean local strain of common carp. Gross total production was 461 kg with a net production of 395 kg, and the Israeli strain grew to about 8 times initial weight and the hybrid about 6 times. Based on an analysis of results of the above mentioned main experiment and the other miscellaneous fish grown in the remaining tanks, it was considered to be feasible to implement a commercial production in this system by improving parts of the system and adding a number of the units. A special problem seems to be an adoption of more effective aeration device when fish loading increases. A solid waste removal system was deviced by use of by-pass flow ana this system worked very efficiently in view of supply water economy. A serious problem encountered in this experiment was heavy outbreaks of the gill-fluke, Dactylogyrus sp. which was relatively easily eradicated with Dipterex or DDVP treatment in the first trials, but later on strains which were resistant to any of these chemicals appeared.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.653-659
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• 2018

High-rise buildings and complex facilities are a representative urban system for the masses, and it requires an increasing role of commodity and safety. Smoke and toxic gasses can cause accidents due to fire in these systems. The purpose of this study is to develop a fiber screen material for emergency evacuation passages that can be avoided quickly and safely in cases of disasters. The fiber screen material is applicable to folding devices for emergency evacuation passages. The material is different from general steel material in that it is lightweight with less burden during storage for a long time in a roll form in a folding device. It also has an excellent secondary function in that it is less affected by radiant heat. Three kinds of fiber screen materials were selected that have good flame retardancy and post-processing characteristics. A performance evaluation was performed by a heat shrinkage test, contact heat test, combustibility test, flame retardancy test, tensile strength test, and tear strength test. As a result, the lightweight fabric shows excellent performance through post-processing, and silicone resin coating can secure safety of the pizza by the fiber screen material performance and radiant heat. The optimum post-treatment conditions were evaluated by performing a burning test after coating two kinds of glass fibers and four types of flame-retardant silicone resins with different weight and thickness.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.5
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• pp.549-557
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• 2017

Numerical studies have been carried out on scrubbers, which are after-treatment devices to satisfy strengthened emission regulations for sulfur dioxide and particulate matter. We investigated the problems with existing scrubbers through numerical analysis and designed and analyzed a new swirl-type scrubber that could solve these problems. As a result, with the swirl-type scrubber, exhaust gas formed a vortex in the lower part of the device, and some of this gas was released along the guide vane through the bottom surface. In this case, the pressure gradient in the vertical direction was not large, but a pressure difference between the inside and outside of the baffle was generated. The shape of the exhaust gas stream was investigated, and when water was not sprayed, the exhaust gas flowed constantly to the outlet along the guide vane, in contrast to when water was sprayed. It was confirmed that the shape of the flow was influenced by the guide vane, nozzle arrangement and water pressure. In the case of the swirl-type scrubber, impact on engine back-pressure was minimal, because differential pressure at the inlet and outlet was less than half of that with a conventional scrubber.

• The Journal of the Korea Contents Association
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• v.14 no.6
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• pp.271-280
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• 2014

The purpose of this study was to offer basic data for developing effective program for promotion elderly people's oral condition, and oral health behavior upon the appearance of denture. This study was performed by utilizing health questionnaire survey and oral examination survey for first year(2010) law data of the 5th korea national health and nutrition examination survey. The research subjects were 1419 people who were aged over 65 and completed the oral examination and oral questionnaire survey. In the general characteristics, the need of denture was indicated highly in the male elderly. Factors of having relationship with a need of denture in oral health condition were indicated to be chewing difficulty(p<0.001) and dental caries(p<0.0001). The case of not using oral hygiene device was high in a need of denture(p<0.001). Also, a case of not dental treatment was indicated to be high in a need of denture(p<0.001). Through these related findings, the elderly's oral condition and oral health behavior were indicated to have high relationship with a need of denture. There is a need of securing basic data for promoting the elderly's oral health in the future and of seeking a plane for application in order to improve the elderly's health in the aging society. Therefore there is a need of securing and seeking elderly's health program which is considered the aging society's characteristics to improve the elderly's health promotion.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.715-719
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• 2009

The phase change electrode board for the bio-information detection through electrical property response of phase change material was developed in this study. We manufactured the electrode board using Aluminum first that is widely used in conventional semiconductor device process. Without further treatment, these aluminum electrodes tend to contain voids in PETEOS(plasma enhanced tetraethyoxysilane) material that are easily detected by cross-sectional SEM(Scanning Electron Microscope). The voids can be easily attacked and transformed into holes in between PETEOS and electrodes after etch back and washing process. In order to resolve this issue of Al electrode board, we developed a electrode board manufacturing method using low resistivity TiN, which has advantages in terms of the step-coverage of phase change($Ge_2Sb_2Te_5$, GST) thin film as well as thermodynamic stability, without etch back and washing process. This TiN material serves as the top and bottom electrode in PRAM(Phase-change Random Access Memory). The good connection between the TiN electrode and GST thin film was confirmed by observing the cross-section of TiN electrode board using SEM. The resistances of amorphous and crystalline GST thin film on TiN electrodes were also measured, and 1000 times difference between the amorphous and crystalline resistance of GST thin film was obtained, which is well enough for the signal detection.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.9
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• pp.397-406
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• 2017

In case of using the existing encrypted algorithm for massive data encryption service under the cloud environment, the problem that requires much time in data encryption come to the fore. To make up for this weakness, a partial encryption method is used generally. However, the existing partial encryption method has a disadvantage that the encrypted data can be inferred due to the remaining area that is not encrypted. This study proposes a partial encryption method of increasing the encryption speed and complying with the security standard in order to solve this demerit. The proposed method consists of 3 processes such as header formation, partial encryption and block shuffle. In step 1 Header formation process, header data necessary for the algorithm are generated. In step 2 Partial encryption process, a part of data is encrypted, using LEA (Lightweight Encryption Algorithm), and all data are transformed with XOR of data in the unencrypted part and the block generated in the encryption process. In step 3 Block shuffle process, the blocks are mixed, using the shuffle data stored with the random arrangement form in the header to carry out encryption by transforming the data into an unrecognizable form. As a result of the implementation of the proposed method, applying it to a mobile device, all the encrypted data were transformed into an unrecognizable form, so the data could not be inferred, and the data could not be restored without the encryption key. It was confirmed that the proposed method could make prompt treatment possible in encrypting mass data since the encryption speed is improved by approximately 273% or so compared to LEA which is Lightweight Encryption Algorithm.

• The korean journal of orthodontics
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• v.39 no.2
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• pp.83-94
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• 2009

Objective: The aim of this study was to investigate the 3-dimensional position of the center of resistance of the 4 maxillary anterior teeth, 6 maxillary anterior teeth, and the full maxillary dentition using 3-dimensional finite element analysis. Methods: Finite element models included the whole upper dentition, periodontal ligament, and alveolar bone. The crowns of the teeth in each group were fixed with buccal and lingual arch wires and lingual splint wires to minimize individual tooth movement and to evenly disperse the forces to the teeth. A force of 100 g or 200 g was applied to the wire beam extended from the incisal edge of the upper central incisor, and displacement of teeth was evaluated. The center of resistance was defined as the point where the applied force induced parallel movement. Results: The results of study showed that the center of resistance of the 4 maxillary anterior teeth group, the 6 maxillary anterior teeth group, and the full maxillary dentition group were at 13.5 mm apical and 12.0 mm posterior, 13.5 mm apical and 14.0 mm posterior, and 11.0 mm apical and 26.5 mm posterior to the incisal edge of the upper central incisor, respectively. Conclusions: It is thought that the results from this finite element models will improve the efficiency of orthodontic treatment.

• Journal of Oral Medicine and Pain
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• v.37 no.4
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• pp.205-211
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• 2012

A 35 year-old female presented with the complaint of sudden occurrence of bite change and concurrent opening limitation, as well as pain in the right temporomandibular joint (TMJ) during mouth opening. From her history it was revealed that she had simple clicking of right TMJ for several years before onset of these symptoms, and that the clicking sound subsided recently after development of opening limitation. On clinical examination, anterior open bite, midline shift of the mandible to right, and premature contacts on left posterior teeth were observed. Maximum mouth opening and lateral movement to left were also restricted. On magnetic resonance images, the right TMJ showed anterior disc displacement without reduction and the posterior joint space is greatly collapsed by retrusion of the condyle. It was thought that the sudden occurrence of occlusal change would be resulted from abrupt displacement of the mandible associated with development of the anterior disc displacement without reduction. The stabilization appliance traction therapy was performed initially for first 3 months along with physical and pharmacologic therapy. However, the anterior open bite and opening limitation didn't resolve and the position of mandible still remained altered. So the stabilization appliance was changed to intermaxillary traction device. Then the mandible returned progressively to normal position and the occlusion became more stable and comfortable. After 5 months of intermaxillary traction therapy, the anterior open bite was dissolved completely and the occlusion became stabilized satisfactorily along with recovery of normal mouth opening range. On post-treatment magnetic resonance image, remodeling of condylar head was observed.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.6
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• pp.645-650
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• 2010

In this research, the problem of combustion and its system in Hyundai Heavy Industries and Sachuan Unison will be analyzed in order to provide some methods of thermal efficiency improvement and help to make a positive influence on fuel savings and their productivity. In forging industries, in order to improve the material properties of the industrial heating elements which are being used, depending on different operation conditions of system equipment and combustion systems, fuel consumption and material properties can get a profound influence. Thus, analyzing about combustion system characteristics of 100 tons heating furnace and heat treatment furnace which are in operation in Hyundai Heavy Industry will be done. In usual, air-fuel ratio is proper for capacity of burner installed in each heating device, otherwise burner gets an automatic turn down ratio. It has a profound influence on heating performance and precision of temperature because it is the fixed characteristics of every industrial furnace. Even if there are some methods to improve the heating performance of a furnace installed with a large capacity burner, it is very difficult to obtain the precision of temperature in maintenance interval. Based on this, performance of burner can be drove to best by improving combustion system. Proper Combustion characteristic for each heating interval was analyzed in heating furnace in Hyundai Heavy Industry. A project plan for improving fuel savings and increasing precision of temperature was presented in this research.