• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 2002.11a
• /
• pp.311-315
• /
• 2002

Polyurethane 발포체는 우수한 단열 및 흡음특성 그리고 반응물질인 polyol과 isocyanate의 성분 및 배합비에 따라 여러가지 제품군으로 특성 설계가 가능하여 LNG 저장탱크, LNG 유조선의 cryogenic insulator, 육상 및 해상용 냉동 및 냉장시설물, 가전제품, 건축단열판넬 등에 널리 사용되고 있다. 그러나 난연성의 결여로 화재 발생시 급격한 연소반응과 유해가스 발생을 동반하여 화재안전 및 건강보건상 중대한 단점을 가지고 있다. 본 연구진은 PU발포체의 물성개선을 통한 난연특성 연구의 일환으로서 montmorillonite, hectorite, vermiculite의 layer silicate를 urethane 원료물질과 혼성발포 공정을 통해 난연복합체를 제조하여 UL94V, LOI, Morphology 등의 시험을 수행하였다.(중략)

• Proceedings of the Mineralogical Society of Korea Conference
• /
• 2001.06a
• /
• pp.132-132
• /
• 2001

옥천변성대의 충주-황강리 지역내 앰피볼라이트의 기원암은 염기성 화성암으로 쏠레이아이트 계열의 변이질암에 속한다. Fe $O^{*}$/MgO값의 변화에 대하여 분별작용에 의해 영향을 받는 주성분 원소와 미량원소들의 변화를 보게되면 Ti $O_2$, Fe $O^{*}$와 불호정성 원소(incompatible element)인 Zr, Nb, Hf, Ta, Th 등은 분별작용동안 증가하는 반면 호정성 원소(compatible element)인 MgO, $Al_2$ $O_3$, Ni, Cr 등은 감소하는 경향을 보여주고 있다. Fe $O^{*}$/MgO, Ti $O_2$ 그리고 Fe $O^{*}$는 심해성 쏠레이아이트 영역으로부터 분화된 경향을 나타내 주고 있다. Ni, Cr은 Fe $O^{*}$/MgO값의 증가에 따라 급속히 감소하며 안정한 대륙과 해저화산의 영역에 도시되고 있으며 칼크-알칼리(CA)와는 관계가 없고 쏠레이아이트의 영역에서 변화 패턴을 보여주어 앰피볼라이트가 활동적인 대륙연변부의 지구조 환경보다는 안정한 대륙이나 해저화산과 관계가 더 있음을 시사한다. 경휘토류 원소(LREE)는 중휘토류 원소(HREE)에 비해 더욱 부화된 특성을 띠고 원자번호가 증가하면서 표준화된 휘토류 원소패턴의 경사가 점차 감소하는 경향을 보여주고 있다. 대부분의 시료들은 큰 Eu이상치를 갖고 있지 않아 마그마 정출 과정동안 사장석의 분별작용이 거의 수반되지 않았음을 지시하고 전체적인 휘토류 원소의 패턴은 거의 평행하게 나타나므로 기원 마그마가 유사함을 의미하고 있다. 비유동성 원소를 이용한 여러 판별도표들을 통해서 본암은 대륙성 현무암질암으로서 판내부 환경에서 유래되었으며 대륙내부 열곡의 알칼리 현무암과 대륙성 현무암 영역에 속하는 것으로 보아서 대륙지각내 열곡작용과 같은 장력운동에 수반되어 생성된 것임을 시사해 주고 있다. 앰피볼라이트의 지각혼성화를 평가하기 위해 이에 필요한 몇 개의 지화학적 매개변수를 계산한 결과 La/Ta, La/Nb, Nb/Th들의 값이 오염 안된 마그마의 값을 지시해 주어 본암이 지각혼성화 작용을 받지 않은 것으로 나타났다. 대부분의 시료들은 P-타입 MORB의 영역에 속하며 소수의 시료가 T-타입 MORB의 영역에 도시되고 있어 본 앰피볼라이트의 생성에는 양적으로 다른 두 가지의 유사한 마그마가 수반된 것으로 추정된다. 것으로 추정된다.

• Journal of the Korean Chemical Society
• /
• v.26 no.4
• /
• pp.235-246
• /
• 1982

The free radical polymerization and copolymerization of N-acetyl ${\alpha}$-aminoacrylic acid were investigated. From the result of kinetic investigation of N-acetyl ${\alpha}$-aminoacrylic acid in DMF at $60^{\circ}C$, a rate equation of $R_p$ = $k_p[M]^{0.97}[I]^{0.59}$ was obtained. The overall activation energy for the polymerization was found to be 25.2 kcal/mole. Copolymerization of N-acetyl ${\alpha}$-aminoacrylic acid with acrylic acid and styrene was carried out for the determination of monomer reactivity ratios. The monomer reactivity ratios for the monomer pairs determined at 70.0{\pm}0.1^{\circ}C$ using benzoyl peroxide as an initiator are; $r_1$(N-acetyl ${\alpha}$-aminoacrylic acid) = 0.49, $r_2$(acrylic acid) = 1.41, $r_1$(N-acetyl ${\alpha}$-aminoacrylic acid) = 0.44, $r_2$(styrene) = 0.91. The values of Alfrey-Price's Q and e parameters for N-acetyl ${\alpha}$-aminoacrylic acid were calculated to be 0.51 and 0.16 for the both systems. Differential thermal analysis and thermogravimetry showed that acrylic acid copolymers have poorer thermal stability as compared with the homopolymer of N-acetyl ${\alpha}$-aminoacrylic acid.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.5B
• /
• pp.563-572
• /
• 2006

In designing the coastal structures, the accurate estimation of wave forces on them is very important. Recently, the empirical formulae such as Goda formula are widely used to estimate wave forces, as well as 2-D hydraulic and numerical model tests. But, sometimes, these estimation methods mentioned above seem to be unreasonable to predict 3-D structure of wave pressure on the coastal structures with 3-D plane arrangement in the real coastal area. Especially, in case of consideration of phase difference at harbor and seaward sides of the large-sized coastal structures like a composite breakwater, it is easily expected that the real wave pressures on each section of coastal structure have 3-D distribution. A new numerical model of 3-D Large Eddy Simulation, which is applicable to permeable structure, is developed to clarify the 3-D structure of wave pressures acting on coastal structure. The calculated wave forces on 3-D structure installed on the submerged breakwater show in good agreement with the measured values. In this study, the composite breakwater is adopted as a representative structure among the large-sized coastal structures and the 3-D structure of wave pressures on it is discussed in relation to the phase difference at harbor and seaward sides of it due to wave diffraction and transmitted wave through rubble mound.

• The Journal of the Acoustical Society of Korea
• /
• v.16 no.4
• /
• pp.106-109
• /
• 1997

In the area of the speech synthesis techniques, the waveform coding methods maintain the intelligibility and naturalness of synthetic speech. In order to apply the waveform coding techniques to synthesis by rule, however, we must be able to alter the pitches for prosody control of synthetic speech. In this paper, we propose a new pitch alteration technique in time-frequency hybrid domain, that compensates phase distortion of the cepstral pitch alteration method with time scaling method in the time domain. This method can remove some phase spectrum distortion which is occurred in conjunction point between the waveforms in continued frames. Also, we can obtain little magnitude spectrum distortion below 1.18% for pitch alteration of 200%.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.44 no.11
• /
• pp.56-64
• /
• 2007

We developed the first automatic design system targeting a promising hybrid CMOS-Nanoelectronics Architecture called CMOL. The CMOL architecture uses NOR gates to implement combinational logic. In this hybrid CMOS-nanoelectronics architecture, logical functions and the interconnections share the nanoelectronics hardware resource. Towards automating the CMOL physical design process, we developed a model for the CMOL architecture, formulated the placement and routing problems for the CMOL architecture subject to the unique CMOL specific constraints, and solved it by combining a placement algorithm with a gate assignment algorithm in a loop. We validated the proposed approach by implementing several industrial strength designs.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.27 no.8
• /
• pp.981-991
• /
• 2003

The purpose of this study is to observe the cultural phenomenon in modern society from the point of view of pastiche, analyze the characteristics of pastiche, create a framework for studying modem fashion and body ornamentation, one of the facts of cultural phenomenon and, based on these aspects, will observe the pastiche phase, which occurred in body ornamentation of modem fashion in the late 1990's Collections. The characteristics of pastiche is that it transcends meaning, alters the usage of objects, raises the beauty of alienation and pursues temporariness. Observing pastiche, according to its definition and characteristics, as it appears in body ornamentation of modem fashion, the results were as follows: First of all, in terms of transcending meaning, body ornamentation of modern fashion is a mixture of all past styles. Secondly, use of objects in body ornamentation of fashion has shown the use of things which have never been used in accessorizing before, such as birdcages, bones of body, castle. Third, in terms of the raising of the beauty of alienation, accessories from countries, which were not high interest groups in the past, such as piercing, scar, corpulent, are being used as high-fashion accessories in body ornamentation of modern fashion. Fourth, in terms of the pursuit of temporariness, external ornamentation in body ornamentation of modern fashion is seen as permanent changes to the outer body, such as tattoos, piercings, hair color and the more temporary changes, such as coloring.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.6 s.237
• /
• pp.876-888
• /
• 2005

Tensile properties and fracture toughness of monolithic aluminum, fiber reinforced plastics and glass fiber/aluminum hybrid laminates under tensile loads have been investigated using plain coupon and single-edge-notched specimens. Elastic modulus and ultimate tensile strength of GFMLs showed different characteristic behaviors according to the Al kind, fiber orientation and composition ratio. Fracture, toughness of A-GFML-UD which was determined by the evaluation of $K_{IC}$ and $G_{IC}$ based on critical load was similar to that of GFRP-UD and was much higher than monolithic Al. Therefore, A-GFML-UD presented superior fracture toughness as well as prominent damage tolerance in comparison to its constituent Al. By separating Al sheet from GFMLs after the test, optical microscope observation of fracture zone of GFRP layer in the vicinity of crack tip revealed that crack advance of GFMLs depended on the orientation of fiber layer as well as Al/fiber composition ratio.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.19 no.2
• /
• pp.235-240
• /
• 2010

The recent trend of vehicle design aims at crash safety and environmentally-friendly aspect. For the crash safety aspect, energy absorbing members should be absorbed with collision energy sufficiently. But vehicle structure must be light weight for the environmentally-friendly aspect, in order to improve fuel efficiency and to reduce tail gas emission. Therefore, the light weight of vehicle must be achieved in a status of securing safety of crash. An aluminum or CFRP (Carbon Fiber Reinforced Plastics) is representative one among the light-weight materials. In this study, impact collapse behavior of circular hybrid thin-walled member is evaluated. The hybrid members are manufactured by wrapping CFRP prepreg sheets outside the aluminum circular members in the autoclave. Because the CFRP is an anisotropic material whose mechanical properties change with its stacking condition, special attention is given to the effects of the stacking condition on the collapse behavior evaluation of the hybrid thin-walled member. Collapse mode and energy absorption capability of the hybrid thin-walled member are analyzed with change of the fiber orientation angle and interface number.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.17 no.3
• /
• pp.34-39
• /
• 2008

In this study, CFRP(Carbon Fiber Reinforced Plastics) that has high specific strength and elastic modulus and low thermal strain was used as a material for the lightweight structural member. CFRP is a fiber material as anisotropic material. The anisotropic material is characterized by the change of its mechanical properties according to stacking orientation angle. CFRP orientation angle was oriented in [A/B]s in order to examine the effect of CFRP orientation angle on the characteristics of energy absorption. CFRP is very weak to the impact from the outside. So, when impact is applied to CFRP, its strength is rapidly lowered. The hybrid material was manufactured by combining CFRP to aluminum which is lightweight and widely used for structural members of the automobile. The hybrid member was shaped as a side member that could support the automobile engine and mount and absorb a large amount of impact energy at the front-end in case of automobile collision. The bending test device was manufactured in accordance with ASTM standard, and mounted to UTM for bending test. For comparing bending characteristics of the hybrid member with those of Aluminum and CFRP member, tests were performed for aluminum, CFRP and hybrid member, respectively.