• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.4
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• pp.141-148
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• 2022

New services such as OTT have appeared, and the value chain of the media industry has formed a complex terrain, and new problems have arisen in terms of fair competition between operators and user protection. However, the problem of introducing OTT under the existing law that classifies services by physical characteristics and technical elements of the network has been criticized in terms of hindering industrial activation due to excessive regulation. The introduction of the new regulatory system has been delayed for a long time despite the dissatisfaction of stakeholders and attempts to legislate

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.2
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• pp.20-27
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• 2022

Hypergolic propellant ignited spontaneously when fuel and oxidizer contact without ignition system. Due to this characteristic, the risk of accidents is high when new propellants are evaluated. Prevention of accidents is very important because the damage can be large when the accident occur. In this work, we proposed non-ignition evaluation method which can replace conventional ignition evaluation method by using microreactor. The reactor was fabricated by MEMS. The heat of reaction as according to fuel and NaBH₄ was estimated. At the condition of highest heat of reaction ignition was observed by drop test.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.267-268
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• 2024

한국통합 물류협회에 따르면 총 택배 물량은 2020년은 약34억 개, 2021년은 약36억 만 개로 매년 꾸준히 성장하였다. 택배 물류센터에서 택배를 고객에게 전달시키기 위해서는 포장, 검수, 진열, 파지, 상차, 하차 등 많은 공정이 필요하다. 고용 인력의 부족, 인건비 상승, 부상의 위험, 높은 노동의 강도 등의 문제가 발생하였고, 소비자들의 입장에서도 제품 손상 또는 배송 지연 등의 여러 가지 문제를 야기해왔다. 본 논문은 로봇과 자율주행 기술을 활용하여 상품의 분류 및 배송과정을 자동화 하는 '스마트 물류창고 시스템'을 제안한다. 컨베이어 벨트를 이용해 택배물품의 분류를 자동화하고 자율주행 차량을 통해 배송을 하게 되고 DB를 통해 물품을 관리하게 되어 효율적인 운영을 가능하게 하고 경제적 손실을 줄인다. 적외선 센서, 바코드 센서를 이용해 컨베이어 벨트 구동 및 물품의 정보를 알 수 있으며 서보모터로 물품을 분류한다. 또한 입출고 차량이 명령을 통해 물품을 자동으로 입고 및 출고하여 DB에게 물품의 정보를 전송한다. 스마트 물류창고 시스템을 통해 인건비 절감, 오 배송, 물품 파손 등이 사라지게 되고 물류창고 뿐만 아니라 다양한 분야에서 적용 할 수 있을 것이다.

• Journal of Adhesion and Interface
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• v.11 no.1
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• pp.15-25
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• 2010

In the present study, isothermal stabilization processes for rayon fabrics were performed at two relatively low temperatures $180^{\circ}C$ and $200^{\circ}C$ for a long period of time. The results of weight loss, dimensional shrinkage, X-ray diffraction and scanning electron microscopic observations studied with the rayon fabrics before and after the isothermal stabilization indicated that the chemical and physical changes of rayon precursor fibers proceeded continuously and slowly at the stabilization temperature below $200^{\circ}C$. And the pre-treatment with four different chemical compounds done prior to stabilization process influenced differently the characteristics of rayon fabrics. As a result, it was noticed that under the given stabilization conditions, $H_3PO_4$ and $Na_3PO_4$ played a role in catalyzing the stabilization reaction of rayon fabric whereas $NH_4Cl$ and $ZnCl_2$ played a role in delaying or retarding the reaction. $H_3PO_4$ showed the lowest percent weight loss of the fabric in the second stabilization conducted at $350^{\circ}C$. It was considered that phosphoric acid, which has a function of flame retardant, contributed to retarding somewhat the subsequent reaction even in the second stabilization step.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.3
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• pp.81-88
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• 2000

Composting of N-rich wastes such as food waste and wastewater sludges can be associated loss of with substantial gaseous N, which means loss of an essential plant nutrient but may also lead to environmental pollution. We investigated the behavior of nitrogenous materials during the first high-rate phase in composting of food waste. Air dried food waste was mixed with shredded waste paper or wood chip and reacted in a bench scale composting reactor. Samples were analyzed for pH, ammonia, oxidized nitrogen and organic nitrogen. The volatilized ammonia nitrogen was also analyzed using sulfuric acid as an absorbent solution. Initial progress of composting reaction greatly influenced the ammonification of organic nitrogen. A well-balanced composting reaction with an addition of active compost as an inoculum resulted in the promoted mineralization of organic nitrogen and volatilization of ammonia. The prolongation of initial low pH period delayed the production of ammonia. It was also found that nitrogen loss was highly dependent on the air flow supplied. With an increase in input air flow, the loss of nitrogen as an ammonia also increased, resulted in substantial reduction of ammonia content in compost. The conversion ratio of initial nitrogen into ammonia was in the range of 28 to 38% and about 77~94% of the ammonia produced was escaped as a gas. Material balance on the nitrogenous materials was demonstrated to provide an information of importance on the behavior of nitrogen in composting reaction.

• Journal of the Korea Concrete Institute
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• v.17 no.1 s.85
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• pp.95-104
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• 2005

The research conducted to study the potential practicability of recycled aggregate concrete by analyzing the characteristics of concretes made of recycled quality aggregates produced by wet and dry process has found the following results. The air content of recycled aggregate concrete increased with increase of the substitut on rate due to mortar included while producing recycled aggregates. However, the concretes with aggregate produced by dry process had relatively low rate of increase in air content. The slump showed generally decreasing trend as the substitution rate of recycled aggregate increased regardless of the wet or dry process. It was assumed that the mortar particles remained in recycled aggregate absorbed the surplus hydration in concrete and decreased fluidity The compressive strength generally decreased as the substitution rate of recycled aggregate increased, however there was an increasing trend as well due to decreasing effect of water-cement ratio when the substitution rate of recycled aggregate reached 25, 50% after mix. This phenomena also appeared in early age, which meant that recycled aggregate concrete should not be retarded in setting when applied in the field. The tensile strength also reached the maximum when wet or dry recycled aggregate replaced with 25%. To conclude, recycled aggregates for concrete produced by wet or dry process are expected to demonstrate essential characteristics of concrete without significant decline in physical or dynamic quality when the substitution rate is below 25% although there are variations subject to water-cement ratio. However, slight differences are expected due to types of recycled aggregate and physical quality.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.194-199
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• 2008

In this study, the effective method to esterify the free fatty acids in jatropha oil was examined. Compared to other plant oils, the acid value of jatropha oil was remarkably high, 11.5 mgKOH/g. So direct transesterification by a base catalyst was not suitable for the oil. After the free fatty acids were esterified with methanol, jatropha oil was transesterified. The activities of four solid acid catalysts were tested and Amberlyst-15 showed the best activity for the esterification. After constructing the experiment matrix based on RSM and analyzing the statistical data, the optimal esterification conditions were determined to be 6.79% of methanol and 17.14% of Amberlyst-15. After the pretreatment, jatropha biodiesel was produced by the transesterification using KOH in a pressurized batch reactor. Jatropha biodiesel produced could meet the major specifications of Korean biodiesel standards; 97.35% of FAME, 8.17 h of oxidation stability, 0.125% of total glycerol and $0^{\circ}C$ of CFPP.

• Polymer(Korea)
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• v.29 no.5
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• pp.440-444
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• 2005

An increase in the surface area of drugs by reducing particle sizes from microns to nanometers has been known as an efficient method to improve the bioavailability of water-insoluble drugs. To prevent drug nanoparticles from aggregation during the processes of drug formulation, a limited number of pharmaceutical inactive ingredients such as hydroxypropyl cellulose has been employed as stabilizers or dispersants. In this study, copolymers of hydrophilic and hydrophobic amino acids were synthesized by the ring opening polymerization of their N-carboxyanhydride monomers and evaluated as novel candidates to stabilize the nanoparticles of a water insoluble drug, naproxen. Naproxen nanoparticles stabilized by synthesized amino acid copolymers were successfully prepared in the size of $200\~500nm$ in 60 min by a wet comminution process. Particle size analysis showed that the effective stabilization performance of copolymers required the hydrophobic moiety content to be higher than $10 mol\%$. However, the molecular weight and morphology of copolymers was not the critical parameters in determining the particle size reduction. Their particle size was found to be stable up to 14 days without significant aggregation.

• The Journal of the Korea Contents Association
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• v.21 no.2
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• pp.78-84
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• 2021

Issues have arisen over the monopoly of housing sales guarantees by the Housing and Urban Guarantee Corporation. If the Ministry of Land, Infrastructure and Transport appoints an additional guarantee institution, there is concern that the property protection between the two parties is insufficient due to excessive competition and the weakening of urban regeneration resources. It argues that housing supply policies for stabilization of the housing market can be smoothly implemented through monopoly projects. This is judged to be an abuse of market dominant position under the Fair Trade Act, and excessive restrictions on pre-sale guarantee requirements may cause delays in business and infringement of property rights of members. First, the establishment of a designation system for market dominant operators of the Fair Trade Commission enables new entry of private guarantee institutions. Second, it is necessary to improve regulations under Article 63 of the Fair Trade Act (consultation on the establishment of laws restricting competition, etc.). Third, through the establishment of the 「Rules on Housing Supply」 under Article 15 (2), the Minister of Land, Infrastructure and Transport can additionally designate a guarantee institution, thereby guaranteeing the right to select a pre-sale guarantee for the business entity. In addition, it is expected that at least one of a number of guarantee insurance companies can be designated to improve the efficiency of the distribution of social benefits, thereby lowering the volatility of housing prices. Listen and suggest.

• Korean Journal of Construction Engineering and Management
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• v.25 no.1
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• pp.32-41
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• 2024

In the construction industry, not only safety accidents, but also various complex risks such as construction delays, cost increases, and environmental pollution occur, and management technologies are needed to solve them. Among them, process risk management, which directly affects the project, lacks related information compared to its importance. This study tried to develop a MATM tunnel process risk classification system to solve the difficulty of risk information retrieval due to the use of different classification systems for each project. Risk collection used existing literature review and experience mining techniques, and DB construction utilized the concept of natural language processing. For the structure of the classification system, the existing WBS structure was adopted in consideration of compatibility of data, and an RBS linked to the work species of the WBS was established. As a result of the research, a risk classification system was completed that easily identifies risks by work type and intuitively reveals risk characteristics and risk factors linked to risks. As a result of verifying the usability of the established classification system, it was found that the classification system was effective as risks and risk factors for each work type were easily identified by user input of keywords. Through this study, it is expected to contribute to preventing an increase in cost and construction period by identifying risks according to work types in advance when planning and designing NATM tunnels and establishing countermeasures suitable for those factors.