• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6604-6610
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• 2015

In this paper, an efficient Wireless Access in Vehicular Environment (WAVE) packet transmission scheme for railroad communication is proposed. WAVE communication is a wireless local area network (WLAN) based communication and it is developed to be suitable for vehicular communication. There has been a lot of study on WAVE's applicability to Intelligent Transport System (ITS). As one of main transportation methods, by using WAVE, quality of railroad communication including WLAN based Communication Based Train Control (CBTC) can be enhanced and variety of railroad communication systems can be integrated into WAVE. However, there are technical challenges to adopt WAVE in railroad communications. For the simplest single-PHY WAVE, time division alternation of 50ms between Control Channel (CCH) and Service Channel (SCH) is required. Since there are delay sensitive railroad traffic types, alternation operation of CCH and SCH may cause performance degradation. In this paper, after identifying a couple of problems based on detailed analysis, a novel packet transmission scheme under railroad environment is proposed. In order to verify if the proposed scheme meets the requirement of railroad communication, WAVE transmission is mathematically modeled.

• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.273-283
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• 1993

Addition of various acids or organic compounds to the electrolyte solution during the electrodeposition of $PbO_2$ on titanium madras substrate strongly affected performance of the deposited $PbO_2$ layer. Results of X-ray diffractometry ascertained that ${\beta}-PbO_2$ was deposited in acidic electrolyte. Among additives used in this experiment, $PbO_2$ with a high oxygen overvoltage was electrodeposited when sodium lauryl sulfate was added, and $PbO_2$ with a lower chlorine overvoltage was electrodeposited when polyethylene glycol was added to the electrolyte solution. The oxygen and chlorine overvoltage of $PbO_2$ was strongly dependent on the stirring provided during the electrodeposition experiment. It was observed by the SEM results that the $PbO_2$ grains deposited when stirring was not provided during the electrodeposition have larger than $PbO_2$ grains deposited by stirring. In the $PbO_2$ deposition under acidic electrolyte, the oxygen overvoltage increased with larger $PbO_2$ grains and the chlorine overvoltage decreased with smaller $PbO_2$ grains. The optimal current efficiency of $PbO_2$ in the presence of perchloric acid was observed at $Pb(NO_3)_2$ 560g/l, $65{\sim}70^{\circ}C$, and pH>1.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.9-18
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• 2008

Curling is caused by the difference in the temperature and humidity by the depth of the slab in Jointed Plain Concrete Pavement. Slab curvature shape and size change due to curling exert a profound influence on the internal stress and roughness of the pavement, affecting structural and functional performance of the pavement. Direct measurement of the slab curvature entails many problems. Many measuring instruments have to be installed at the early-stage of the pavement construction, and the behavior of the slab curvature needs to be measured accurately from the early-stage. Moreover, the cost and technical difficulty are very formidable to measure the slab curvature. This study develops a measurement method for slab curvature in jointed concrete pavement at any given time by applying Power Spectrum Density Analysis and Inverse Fast Fourier Transformation to the profile data, that can be easily obtained at the construction field site. The effectiveness of this developed method is verified by measuring the profile data of the test road of jointed concrete pavement at an inland central expressway by the hour and by examining the result of extracting the slab curvature shape from this profile data. Additionally, the profile data of CRCP(Continuously Reinforced Concrete Pavement) sections on the same expressway were obtained and analyzed at the same time. The validity of the method developed for the slab curvature shape extraction is verified by comparing the result from the analysis of the profile data of CRCP sections with that from the analysis of the prof1Ie data of jointed concrete pavement sections.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.4
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• pp.347-356
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• 2008

The purpose of Radioactive Waste Acceptance Criteria(WAC) is to verify a radioactive waste compliance with radioactive disposal facility requirements in order to maintain a disposal facility's performance objectives and to ensure its safety. To develop WAC which is conformable with domestic disposal site conditions, we furthermore analysed the WAC of foreign disposal sites similar to the Kyung-Ju disposal site and the characteristics of various wastes which are being generated from Korea nuclear facilities. Radioactive WAC was developed in the technical cooperation with the Korea Atomic Energy Research Institute in consideration of characteristics of the wastes which are being generated from various facilities, waste generators' opinions and other conditions. The established criteria was also discussed and verified at an advisory committee which was comprised of some experts from universities, institutes and the industry. So radioactive WAC was developed to accept all wastes which are being generated from various nuclear facilities as much as possible, ensuring the safety of a disposal facility. But this developed waste acceptance criteria is not a criteria to accept all the present wastes generated from various nuclear facilities, so waste generators must seek an alternative treatment method for wastes which were not worth disposing of, and then they must treat the wastes more to be acceptable at a disposal site. The radioactive disposal facility WAC will continuously complement certain criteria related to a disposal concentration limit for individual radionuclide in order to ensure a long-term safety.

• Journal of Energy Engineering
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• v.28 no.4
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• pp.35-41
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• 2019

In order to overcome these disadvantages, the halogen light source, which was previously used as a vehicle fog light, has increased power consumption and a short lifetime, and thus, an automobile light source is gradually being replaced with an LED. However, when the vehicle LED fog light is turned on, there is a disadvantage in reducing the life of the fog lamp due to the high heat generated from the LED. The heat generated by the LED inside the fog lamp is mainly emitted by the heatsink, but most of the remaining heat is released to the outside through convection. When cooling efficiency decreases due to convection, thermal energy generates heat to lenses, reflectors, and bezels, which are the main parts of lamps, or generates high temperatures in LED, thereby shortening the life of LED fog lights. In this study, we tried to improve the heat dissipation performance by convection in addition to the heat dissipation method by heat sink, and to determine the installation location of vents that can discharge the internal air or intake the external air of LED fog lamp for vehicle. Thermal fluid analysis was performed to ensure that the optimal data were reflected in the design. The average velocity of air increased in the order of Case3 and Case2 compared to Case1, which is the existing prototype, and the increase rate of Case3 was relatively higher than that of other cases. This is because the vents installed above and below the fog lamps induce the convective phenomena generated according to the temperature difference, and the heat is efficiently discharged with the increase of the air speed.

• Korean Journal of Environmental Agriculture
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• v.34 no.4
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• pp.294-302
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• 2015

BACKGROUND: Chemical accidents have increased owing to chemical usage, human error and technical failures during the last decades. Many countries have organized supervisory authorities in charge of enforcing related rules and regulations to prevent chemical accidents. A very important part in chemical accidents has been coping with comprehensive first aid tool. Therefore, the present research has provided information with the initial applications concern to the rapid analysis of hazardous material using instruments in vehicle of field mode after chemical accidents. METHODS AND RESULTS: Mobile measurement vehicle was manufactured to obtain information regarding field assessments of chemical accidents. This vehicle was equipped with four instruments including gas chromatography with mass spectrometry (GC/MS), Fourier Transform Infrared Spectroscopy (FT-IR), Ion Chromatography (IC), and UV/Vis spectrometer (UV) to analyses of accident preparedness substances, volatile compounds, and organic gases. Moreover, this work was the first examined the evaluation of applicability for analysis instruments using 20 chemicals in various accident preparedness substances (GC/MS; 6 chemicals, FT-IR; 2 chemicals, IC; 11 chemicals, and UV; 1 chemical) and their calibration curves were obtained with high linearity ( r ² > 0.991). Our results were observed the advantage of the high chromatographic peak capacity, fast analysis, and good sensitivity as well as resolution. CONCLUSION: When chemical accidents are occurred, the posted measurement vehicle may be utilized as tool an effective for qualitative and quantitative information in the scene of an accident owing to the rapid analysis of hazardous material.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.308-313
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• 1999

Total polar lipid produced from the soybean oil and lard by heating with different surface area at $185^{\circ}C$ were measured by silica gel column chromatography. Further, the polar lipid was fractionated by high performance size exclusion chromatography-evaporative light scattering detector (HPSEC-ELSD). The HPSEC system was composed of two GPC columns $(100\;{\AA}\;and\;500\;{\AA})$ and a THF mobile phase. With this system it was possible to fractionate into the free fatty acid, diglyceride, triglyceride monomer, triglyceride dimer and triglyceride polymers. The triglyceride monomer, triglyceride dimer and triglyceride polymers significantly increased as the heating time and surface area increased. But diglyceride and free fatty acid did not increased as the heating time and surface area increased. Triglyceride polymer (r>0.93), triglyceride dimer (r>0.97), triglyceride monomer (r>0.95) showed a high correlation with polar lipid content. On the other hand, diglyceride (r<0.68) and free fatty acid (r<0.76) were not significantly correlated with the polar lipid content. These results indicated that a major oxidative components formed during thermal oxidation were triglyceride polymers and triglyceride dimer and triglyceride monomer.

• Korean Journal of Construction Engineering and Management
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• v.16 no.2
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• pp.12-20
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• 2015

The public employers are faced the mounting importance of decision process to settle the optimum VE delivery system of such public facilities buildings and etc. The elements of decision process of the public employer are formed in the various relationships of the concerned and when the projects are coming into effect, the decision process in the VE delivery method and the selection of contractor will be the name of the game. The decision process in the VE delivery method and the selection of contractor are created a case to be one and the same as well as initiates a consistency for the performance. However, the function and role of the public employer are projective accordingly to the organization of employer and the employer especially no system is equal to the capability of perfect evaluation and verification of the ability of the employer. Especially the lowest bidder policy that started with justification to increase the competitiveness and technical capability of the contractors through the completion in between contractors has been providing the hotbed for insolvency, irregularity and irrationality as a result. From this point of view it is declared that the buildup the edifice of supporting system in the process of decision to recover the mutual trust and respect of the concerned in the VE delivery system with the technostress and the systematization based on drawing the elements which affect the decision process of public employer.

• Geophysics and Geophysical Exploration
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• v.12 no.1
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• pp.41-48
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• 2009

Natural magnetic fields are attenuated by electrically conductive water. For that reason, marine magnetotelluric surveys have collected data at long periods (1000-100 000 s). The mantle structure has been the main target of seafloor magnetotelluric measurements. To ascertain crustal structure, however, electromagnetic data at shorter periods are important, e.g. in investigations of megathrust earthquake zones, or in natural resource surveys. To investigate of the former, for example, electromagnetic data for periods of less than 1000 s are necessary. Because no suitable ocean bottom electromagnetometer (OBEM) has been available, we have developed a small OBEM and ocean bottom electrometer (OBE) system with a high sample rate, which has an arm-folding mechanism to facilitate assembly and recovering operations. For magnetic observation, we used a fluxgate sensor. Field observations were undertaken to evaluate the field performance of our instruments. All instruments were recovered and their electromagnetic data were obtained. Results of the first experiment show that our system functioned well throughout operations and observations. Results of other field experiments off Tottori support the claim that the electromagnetic data obtained using the new OBEM and OBE system are of sufficient quality for the survey target. These results suggest that this device removes all instrumental obstacles to measurement of electromagnetic fields on the seafloor.

• Journal of dental hygiene science
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• v.15 no.2
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• pp.153-158
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• 2015

The aim of this study was to provide practical information regarding career exploration to dental hygiene students. This study interviewed 15 senior dental hygienists (graduates of Y University Dental Hygiene program) who have worked in non-clinical fields for about three months from January 14, 2014 to April 28. The most frequently mentioned pieces of information that the senior dental hygienists wanted to convey to dental hygiene students were as followed. Contrary to popular belief, clinical experience was also required in non-clinical fields as the importance of clinical experience was quite often and widely emphasized and applied in such fields. High academic excellence and clinical performance were expected of junior dental hygienists and the senior dental hygienists expressed their hope for their juniors to pioneer new fields and areas of work that a dental hygienist can do. Most of the senior dental hygienists pointed out that to develop technical tools for career exploration as early as possible, such as during undergraduate years and to think about which career path to take, whether it is clinical or academic were significantly important factors for desirable career outcomes. Based on the results of this study, undergraduate dental hygiene students should be provided with opportunities to consider and explore various career paths during their undergraduate years and to communicate with their seniors for hands-on experience-based advices. This would in turn broaden each student's perspective beyond their knowledge or thought about the professional filed of dental hygiene. It was found that the majority of the senior dental hygienists agreed that their clinical experience was the source of their self-competence as a dental hygienist. Our study could be utilized as a valuable resource for future dental hygienists who wish to work in non-clinical fields.