• The Journal of Korean Society for Radiation Therapy
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• v.29 no.1
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• pp.19-26
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• 2017

Purpose: The application of density override is very important to minimize dose calculation errors by fiducial markers of metal material in proton treatment plan. However, density override with actual material of the fiducial marker could make problem such as inaccurate target contouring and compensator fabrication. Therefore, we perform density override with surrounding material instead of actual material and we intend to evaluate the usefulness of density override with surrounding material of the fiducial marker by analyzing the dose distribution according to the position, material of the fiducial marker and number of beams. Materials and Method: We supposed that the fiducial marker of gold, steel, titanium is located in 1.5, 2.5, 4.0, 6.0 cm from the proton beam's end of range using water phantom. Treatment plans were created by applying density override with the surrounding material and actual material of the fiducial marker. Also, a liver cancer patient who received proton therapy was selected. We located the fiducial marker of gold, steel, titanium in 0, 1.5, 3.5 cm from the proton beam's end of range and the treatment plans were created by same method with water phantom. Homogeneity Index(HI), Conformity Index(CI) and maximum dose of Organ At Risk(OAR) in Planning Target Volume(PTV) as the evaluation index were compared according to the material, position of the fiducial marker and number of beam. Results: The HI value was more decreased when density override with surrounding material of the fiducial marker was performed comparing with density override with actual material. Especially the HI value was increased when the fiducial marker was located farther from the proton beam's end of the range for a single beam and the fiducial marker's position was closer to isocenter for two or more beams. The CI value was close to 1 and OAR maximum dose was greatly reduced when density override with surrounding material of the fiducial marker was performed comparing with density override with actual material. Conclusion: Density override with surrounding material can be expected to achieve more precise proton therapy than density override with actual material of the fiducial marker and could increase the dose uniformity and target coverage and reduce the dose to surrounding normal tissues for the small fiducial markers used in clinical practice. Most of all, it is desirable to plan the treatment by avoiding the fiducial marker of metal material as much as possible. However, if the fiducial marker have on the beam path, density override of the surrounding material can be expected to achieve more precise proton therapy.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.341-346
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• 2020

Motion sickness or dizziness caused by visual and other sensory inconsistencies In virtual reality content seems to be a major problem. To solve the problem, research has been actively underway to satisfy the five senses. Among them, the most researches on the touch are many studies on hardness and texture, but the studies on temperature seem relatively small. Therefore, in this paper, we present a calculation model that can sense the temperature derived from the principle of heat energy moving from high temperature to low temperature, not the temperature of the material. Because heat energy is determined by the heat conductivity, temperature, and area of contact, which are the inherent characteristics of a material, the degree of heat felt by a person depends on the type of material, the temperature of the material and the area of contact with the object. The thermal energy shift per unit time of the material was calculated using the thermal conductivity law and the specific heat formula, and the thermal energy reproduction method that changes per unit time of the material was studied using the thermoelectric element.

• Fire Science and Engineering
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• v.25 no.3
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• pp.20-27
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• 2011

This paper studied combustion characteristics of the sponge type sound-absorbing materials extensively used on building interior. To estimate of the combustion characteristics, we carried out combustion experiment of general type and incombustibility type sound-absorbing materials. And then to evaluate the suitability of the sponge type sound-absorbing materials, we measured heat release rate (HRR) and smoke density (Ds) of the sound-absorbing materials using by a cone-calorimeter. From the combustion experimental results, general type sound-absorbing materials were rapid burned simultaneously with ignition and the incombustibility type sound-absorbing materials had all gone out simultaneously with ignition. Measured results of HRR and Ds were not satisfied KS F ISO 5660-1 and IMO FTP Code, form the results, the sponge type sound-absorbing materials were ill-suited for using building interior.

• Resources Recycling
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• v.17 no.1
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• pp.43-50
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• 2008

In this study, we carried out the research on triboelectrostatic separation for materials separation of PET & Nylon recovered to waste plastic beer bottle. From the research on charging characteristic for choice of charging materials, it was found that PMMA was optimum charging material to make high charging amount with opposite polarity for PET & Nylon in waste plastic beer bottle. Therefore, we manufactured a charger of pipe line and cyclone type using PMMA material for separation of PET and Nylon. At optimum test conditions that used PMMA pipe line and cyclone charger developed in this study, we developed a triboelectrostatic separation technique that can separate PET plastic up to grade of 99.6% and recovery of 88.2%. We established new separation technology that can recycle the PET and Nylon recovered from waste plastic beer bottle.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.511-511
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• 2012

핵 융합로는 고밀도, 고에너지 플라즈마에 지속적으로 노출되며 고열부하 및 중성자, 플라즈마 이온에 의한 물성변화에 대한 다양한 핵 융합로 구축 재질의 실험데이터가 요구된다. 특히 핵 융합 반응의 핵심연료인 삼중수소의 재질별 누설거동 특성은 삼중수소의 블랑켓에서의 증식율, 열 교환기 및 공급과 회수과정에서의 손실율, 저장, 취급 및 차폐 등의 계산에 활용되므로 핵 융합로의 안전성과 경제성 확보 측면에서 매우 중요하다. 따라서 핵 융합로 구축 재질 선정시 삼중수소의 누설거동 특성은 반드시 고려되어야 한다. 본 연구는 삼중수소 누설거동 특성 해석을 위한 기초실험으로, 수소동위원소를 사용하는 누설거동실험 장치를 설계 제작하여 누설 거동실험을 수행하였다. 누설 가스로는 수소를 사용하였고, 시편은 스테인레스 스틸(SUS-304)을 사용하였으며, 시편의 가열온도는 500, 600, 700, $800^{\circ}C$에서 각각 수소누설거동 실험을 실시하였다. 수소에 대한 SUS-304 재질의 permeability, diffusivity, solubility에 대한 실험 결과를 발표하고자 한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.2
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• pp.268-277
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• 2000

Nowadays, the interference between neighbor basestations is getting higher as mobile communication services expand, then the increase of the interference causes IMD(Intermolulation Distortion) problems for not only active devices but also passive devices. In this paper, we have designed and assembled several adapters having variable plating thickness and materials to analyze PIMD(Passive Intermodulation Distortion) mechanisms for coaxial cables which is one of the representative passive RF devices. The measurement results of the assembled adapters show that IM level depends on conductivity of plating materials, plating thickness, device structure, aging effect and so on. Furthermore, we have obtained PIMD mechanisms and some control methods of PIMD from the results.

• Korean Journal of Food Science and Technology
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• v.20 no.2
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• pp.252-255
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• 1988

The molding characteristics, hardness and overall quality of the Korean style disposible food tray made from the low and medium density polystyene sheets were investigated and the results were obtained as follows. The volume difference of 8 sectional trays was 56.4% between the two materials, and that of 5 sectional trays was 41.8%. The more the sectional number of the tray, the larger the volume difference. Medium density polystylene tray had the better solid characteristics and overall acceptance than the low density polystlene tray.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.45-48
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• 2008

Micro power generators have been studying to provide high power that micro systems require. Micro power generators need micro combustor. Swiss-roll combustor has been studied about scale, geometry, material. From previous study experiments have shown that swiss-roll combustors require thin walls with low thermal conductivity for maximum performance at small scales. In this work, polyimide combustors with low thermal conductivity and thin thickness are built and tested.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.363-369
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• 2006

Effects of three packing materials and exposure time on the mortality of Plodia interpunctella and Tribolium castaneum were studied using $CO_{2}-modified$ atmosphere control. Materials used were triple layered craft paper (KKK), triple layered craft paper with one laminate coating layer (KLK), and triple layered craft paper with one HD film coating layer (KHK). In the test balls (${\phi}1.2\;m$) containing 85% $CO_{2}-modified$ atmosphere, concentration of $CO_{2}$ in small packing envelopes ($9.8{\times}9.8cm$) made of the materials after one day was higher in KKK ($26.67{\pm}0.58%$) than KLK ($23.33{\pm}0.58%$) or KHK ($20.67{\pm}0.58%$). Both P. interpunctella and T. castaneum showed higher mortality in KKK than in either KLK or KHK Similar results were obtained by larger space ($9{\times}4{\times}3m$) and packing volume (20 kg) studies. The effect of the packing materials was clearer on T. castaneum more tolerant to $CO_{2}$ than P. interpunctella. Regression of the insect mortality on cumulative concentration time (${\int}_{0}^{t}c{\times}tdc{\approx}{\sum}concentration{\times}time$) was highly significant. Control of P. interpunctella and T. castaneum by $CO_{2}-modified$ atmosphere were discussed in relation to packing materials, cumulative concentration time of $CO_{2}$ and food products.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.253-259
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• 2021

Plastic wastes generated from household waste are separated by mixed discharge with foreign substances, and recycling is relatively low. In this study, the effect of the ratio and content of mixed plastic waste coarse aggregate(MPWCA)s and mixed plastic waste fine aggregate(MPWFA)s filled with blast furnace slag fine powder on the slump and compressive strength of concrete was evaluated experimentally. The MPWCAs were found to have a similar fineness modulus, but have a single particle size distribution with a smaller particle size compared to coarse aggregates. However, the MPWFAs were found to have a single particle size distribution with a larger fineness modulus and particle size compared to fine aggregates. Meanwhile, the effect of improving the density and filling pores by the blast furnace slag fine power was found to be greater in the MPWFA compared to the MPWCA. As the amount of the mixed plastic waste aggregate(MPWA)s increased, the slump and compressive strength of concrete decreased. In particular, the lower the slump and compressive strength of concrete was found to decrease the greater the amount of MPWFA than MPWCA when the amount of MPWA was the same. This is because of the entrapped air and voids formed under the angular- and ROD-shaped aggregates among the MPWFAs. On the other hand, the addition of the admixture and the increase in the unit amount of cement were found to be effective in improving the compressive strength of the concrete with MPWAs.