• Structural Engineering and Mechanics
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• 제65권2호
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• pp.183-190
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• 2018

The prestressed concrete (PSC) technology that was first developed by Freyssinet has significantly improved over the past century in terms of materials and structural design in order to build longer, slender, and more economic structures. The application of prestressing method in structures, which is determined by the pre-tension or post-tension processes, is also affected by the surrounding conditions such as the construction site, workforce skills, and local transportation regulations. This study proposes a prestressed concrete girder design based on a hybrid segment concept. The adopted approach combines both pre-tension and post-tension methods along a simple span bridge girder. The girder was designed using newly developed 2400 MPa PS strands and 60 MPa high-strength concrete. The new concept and high strength materials allowed longer span, lower girder depth, less materials, and slender design without affecting the lateral stability of the girder. In order to validate the applicability of the proposed hybrid prestressed segments girder, a full-scale 35 m girder was fabricated, and experimental tests were performed under various fatigue and static loading conditions. The experimental results confirmed the feasibility of the proposed long-span girder as its performance meets the railway girder standards. In addition, the comparison between the measured load-displacement curve and the simulation results indicate that simulation analysis can predict the behavior of hybrid segments girders.

• 디자인학연구
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• 제19권3호
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• pp.105-116
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• 2006

In product manufacturing industries, a recent issue is the green concept. The green concept is a complicated area. If the green concept is for products, its serious issues have to be criticized. Although the importance of the green concept has overflowed, its influences have not been disputed vigorously. So this study is to critic the serious issues of the green concept in aesthetics in product design, manufacturing, and products' prices. The green environment has four representative elements: systems, policies, minds, and technologies, but they are not in the field of design. An element of the green concept, green design is also a sub concept for design, so it should be based on aesthetics. It is green aesthetics. But since green design first appeared, it has never approached by aesthetics because it has mostly had social meanings and expectations. So for green aesthetics, to think about what makes a product, and what can be aesthetic issues among them are important. Products consist of form, structure, material, and technology. Form means different shapes in a structure, but there cannot be any specific directions for a green concept. Structure has two kinds: interior and exterior structure. While interior structure has a technological character, exterior structure is deeply related with aesthetics, but it has also no chance for green concept. Material can be divided as two also: aesthetic and technological. Aesthetics materials mean the colors, opacity, and tactile sense of materials, but they are not aesthetic issues. Technological materials are recycled materials or non-recycled materials. Even if recycled materials are used today, they are close to systems or policies rather than aesthetics. With this result, green aesthetics is a very difficult concept. Second, green products are usually 30% more expensive than general products. But every consumer has his or her own economical conditions, and nobody can coerce consumers into buying expensive green products for green environments. And green products without good quality cannot satisfy consumers. This means that green concept is not accomplished by just manufacturing green products. Third, although a lot of proposals have appeared as green design in exhibitions, most of them are close to craft because they are so hard to be manufactured. Manufacturing is the first consideration for products. These three issues are enough to explain why green concept is complicated in manufacturing products. If they are not solved, the green concept is just a fiction. So if this study proposes a turning point against blind green-oriented atmosphere, it will be meaningful enough.

• Human Ecology Research
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• 제56권2호
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• pp.167-174
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• 2018

This study investigated consumer innovativeness by examining a relationship model of innate innovativeness, product interest, product-specific innovativenss, and actualized innovativeness for eight product items as well as observed gender differences in the variables. The eight product items for the survey were smartphones, movies, clothing, cars, skin care products/cosmetics, traveling, AI products, and books. An online survey was conducted in January 2018, and 400 responses from male and female consumers in their twenties and thirties, were analyzed using reliability test, descriptive statistics, regression, and ANCOVA. The positive effect of innate innovativeness and product interest on product-specific innovativeness, and positive effect of innate innovativeness and product-specific innovativeness on actualized innovativeness were confirmed. Product interest was found to have a stronger power on product-specific innovativeness than innate innovativeness. Gender differences in product interest, product-specific innovativeness, and actualized innovativeness were identified as hypothesized. Female consumer's clothing interest, clothing innovativenss, and actualized clothing innovativeness were higher than male consumers; in addition, male consumer's cars and AI interest, cars and AI innovativenss, and actualized cars and AI innovativeness were higher than female's. The controversial results that indicated the higher innate innovativeness of male consumers useful to further in-depth discussion and research. This study contributed to the theory construction of consumer innovativeness research areas and offered practical implications for new product launching and customer relationship management.

• 대한금속재료학회지
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• 제50권4호
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• pp.285-292
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• 2012

Hot ductility behavior of precipitation-hardened low-carbon iron alloys containing 0.02 wt% Ti and 0.05 wt% Nb was characterized by a hot tensile stress test. Carbon (0.05, 0.1, 0.25 wt%) and boron (0.002 wt%) contents were varied to study the effect of precipitates on the high-temperature embrittlement of the alloys in the temperature range of $600{\sim}800^{\circ}C$. Ductility loss was observed at $700^{\circ}C$ for the tested alloys. The cause of the ductility loss was mainly attributed to the carbides and ferrite films formed at the grain boundaries during deformation. Although the carbon content tended to raise the total fraction of Nb (C, N), the precipitates were formed mostly in the grain interior as the precipitation temperature was raised above the deformation temperature by the high carbon content. Hence, carbon in excess suppressed the hot ductility loss. Meanwhile, boron addition improved the hot ductility of the alloys. The improvement is likely due to the boron atoms capturing carbon atoms and thus retarding the carbide formation.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2007년도 정기학술발표대회 논문집
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• pp.441-445
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• 2007

정부의 대량주택공급정책 등으로 인한 고객중심으로의 시장변화는 자연히 주택 공급업체로 하여금 품질의 경쟁시대를 맞이하도록 하였다. 이러한 품질경쟁시대에서 빠르게 변화하는 고객의 요구품질에 부응하는 주택상품기획 방향을 모색하기위한 선행연구로서 현재 우리 주택시장에서 이루어지는 주택상품의 단위세대 품질의 차별화 사례유형에 대한 실태분석을 실시하였다. 조사 및 분석 결과 많은 사례들이 단순히 마감자재의 고급화나 일시 유행적인 친환경자재의 사용과 부분적이고 단속적인 생활편의품과 설비시스템의 건축요소와의 결합 등을 통한 상품풀질의 차별화를 꾀하고 있었다. 본 연구결과 주택상품의 차별화 기획은 고객을 중심으로 하여 단위세대의 품질 요소 중 건축지향적인 평면 및 인테리어요소와 기술지향적인 설비 및 제품요소의 유기적인 융합을 통합 품질의 차별화가 이루어져야 할 것으로 판단된다. 향후 주택상품기획단계에서는 고객 개념의 재정립을 통한 사람중심의 지속가능한 차별화 계획요소에 대한 연구 및 고객 지향적 주택상품기획 절차의 마련이 필요한 것으로 연구되었다.

• Journal of the Korean Wood Science and Technology
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• 제51권5호
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• pp.410-418
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• 2023

In this study, the combustion characteristics of the Tulip tree, which is the representative broad-leaved afforestation tree in Korea, were analyzed. The flame retardant performance of the Tulip tree was analyzed by analyzing combustion characteristics on a total of three test samples; flame retardant treated, both flame retardant and oil stain-treated, and untreated. Then the flame retardance grade was classified for each of them. According to the result, test samples showed the strongest flame retardance were in order of flame retardant treated (C), both flame retardant and oil stain-treated (B), and untreated (A). As a result of analyzing the total heat emission and maximum heat emission rates, which is the evaluation standard for interior materials of Korean domestic buildings, test samples with flame retardant treat or flame retardant and oil stain treat were qualified for the flame-retardant standard. Both flame retardant and oil stain-treated samples showed higher total heat release (THR) and heat release rate compared to flame retardant-treated samples as the oil causes combustion with oxygen. On the other hand, they didn't qualify the THR in Quasi-non-combustible standards. To determine the correlation between the physical and combustion characteristics of wood, the combustion characteristics of other diffuse porous wood species, with which the Tulip tree is affiliated were analyzed, and noticed that the characteristic correlates with the density and quantity of wood. The results of this study are expected to be used as basic information on the combustion characteristics of the Tulip tree.

• 한국건설순환자원학회지
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• 제11권3호
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• pp.25-28
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• 2016

• 한국건설순환자원학회지
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• 제12권4호
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• pp.47-54
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• 2017

• 한국건설순환자원학회지
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• 제14권3호
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• pp.39-43
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• 2019

• 한국분말재료학회지
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• 제24권1호
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• pp.29-33
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• 2017

Titanium carbide (TiC) powders are successfully synthesized by carburization of titanium hydride ($TiH_2$) powders. The $TiH_2$ powders with size lower than $45{\mu}m$ (-325 Mesh) are optimally produced by the hydrogenation process, and are mixed with graphite powder by ball milling. The mixtures are then heat-treated in an Ar atmosphere at $800-1200^{\circ}C$ for carburization to occur. It has been experimentally and thermodynamically determined that the de-hydrogenation, "$TiH_2=Ti+H_2$", and carburization, "Ti + C = TiC", occur simultaneously over the reaction temperature range. The unreacted graphite content (free carbon) in each product is precisely measured by acid dissolution and by the filtering method, and it is possible to conclude that the maximal carbon stoichiometry of $TiC_{0.94}$ is accomplished at $1200^{\circ}C$.