• 한국추진공학회지
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• 제2권3호
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• pp.107-115
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• 1998

복합재료와 금속 튜브 사이의 좁고 긴 원통형 공간을 EPDM(Ethylene propylene dien ter polymer)으로 충전하는 연구를 수행하였다. 휴대용 유도무기의 추진기관을 개발하기 위하여 소형 연소관 조립체를 설계하고 제작하였다. 연소관 조립체는 연소관 금속튜브, 연소관 내열재, 그리고 연소관 단열재로 이루어져 있는데 연소관 내열재는 탄소/페놀릭을 사용하여 롤링 공법으로 제작하였으며 연소관 단열재는 EPDM을 사용하여 TPM 공법으로 제작하였다. EPDM의 조성 선정을 위하여 내열 삭마특성, 열분해특성 실험을 수행하였으며 흐름성, 접착성, 경도측정 등을 통하여 최종 조성을 결정하였다. 연소관 조립체를 제작하기 위한 EPDM 충전을 위하여 TPM 공법을 설계하고 금형과 치구를 제작하였다. 충전된 연소관 조립체는 비파괴검사를 통하여 접착, 기공 등을 검사하여 최종 선정되었다.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1861-1866
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• 2012

The new semiconducting copolymers with 4,4-dialkyl-$4H$-cyclopenta[2,1-$b$:3,4-$b^{\prime}$]dithiophene and 2,2-dimethyl-$2H$-benzimidazole units were synthesized. The fused aromatic rings, such as cyclopentadithiophene (CPDT) unit, can make the polymer backbone more rigid and coplanar, which induces long conjugation length, narrow band gap, and strong intermolecular ${\pi}-{\pi}$ interaction. The stacking ability was controlled through attaching of linear or branched alkyl side chains. The spectra of PEHCPDTMBI and PHCPDTMBI in the solid films show absorption bands with maximum peaks at 401, 759 and 407, 768 nm, and the absorption onsets at 925 and 954 nm, corresponding to band gaps of 1.34 and 1.30 eV, respectively. The devices comprising PHCPDTMBI with $TiO_X$ showed a $V_{OC}$ of 0.39 V, a $J_{SC}$ of 1.14 $mA/cm^2$, and a $FF$ of 0.34, giving a power conversion efficiency of 0.15%. The PHCPDTMBI with linear alkyl chain on CPDT shows good solubility in organic solvent with higher PCE value than that of PEHCPDTMBI.

• 대한치과보철학회지
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• 제37권2호
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• pp.256-268
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• 1999

Submerged implants require secondary surgical uncovering of implants after healing period of 3-6 months. In surgical methods, there are surgical scalpel, tissue punch, electro-surgical, and laser-used uncovering, and so forth The objectives of this study are investigation and assessment of 1) thermal change in clinical application for uncovering of HA-coated implant and pure titanium implant irradiated by pulsed Nd-YAG, $CO_2$, and Er-YAG laser. 2) surface change of cover screws aaer irradiation using laser energy. The temperature of apex & side wall of implants were recorded at 10sec, 20sec, 30sec after 30sec irradiation to implant healing screw; 1) pulsed Nd-YAG laser; 2W, 20pps, contact mode 2) $CO_2$ laser; water-infused & non-water infused state, 2.5-3.5W, contibuous mode, noncontact mode 3) $CO_2$ laser ; non-water infused state, 3W, superpulse, noncontact. mode 4) Er-YAG laser; (1) non-water infused state, 10pps, 60mj, contact mode (2) water-infused state, 10pps, 60mj, 80mj, 101mj, contact mode. According to the results of this study, pulsed Nd-YAG laser is not indicated because of increased thermal change and pitting of metal surface of implant cover screw. By contrast, $CO_2$ laser & Er-YAG laser are presumed to indicate because of narrow range of thermal change & near abscence of thermal damage of metal surface. Dental laser is thought to be much helpful to surgical procedure when it is used as optimal power and time condition considering characteristics and indications of each laser. Further research is needed to verify that these techniques are safe and beneficial to implant success.

• 한국의상디자인학회지
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• 제2권2호
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• pp.113-136
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• 2000

Problems and improvemental measures for the historical inquiry of TV drama costumes and for the reproduction of them were investigated. For this study, the MBC historical drama 'The way of the Great King' started on march 24 in 1998 and ended on september 26 in 1998 was selected as the subject. The reasons why the drama was selected are as follows. First, the historical background was the time of King Young ＆ drama introduced various kinds of costumes Joungjo, which is the starting era of traditional costumes peculiar to Korea. Second, the based on the historical inquiry of that time. There is a limitation in the process of historical inquiry about the costumes of that time because we don't have enough research data such as relics, remains, references, literary works, pictures, etc. Although, in some cases, exact historical inquiry about the costumes were made, they could not be reproduced in the original forms due to several reasons: the absence of the materials of that time, structural changes including length and size for convenience of action, alterations of the manufacturing method for the reuse, addition of the gorgeous and various olors for the enhancement of image quality, variations in colors according to the actor's character, modulations of the structures and colors by the producer's intention, and the restraints in time and money for manufacturing. In view of these situations, it seems to be difficult for us to settle the problems occurring between the historical inquiry about the traditional costumes and the reproduction of them in drama. However, the costumes presented in historical drama have the meanings to provide informations of that time with TV audience. Therefore I think that it is necessary to narrow the gap between the historical inquiry of TV drama costumes and for the reproduction of hem, First, It should be restrained that each broadcasting stations show the costumes under the similar situations of the same age in different ways. Second, We need to unify the inquiry systems concerning historical drama costumes, In addition to this, it is also necessary for broadcasting stations to establish internet sites of traditional costumes for communication.

• 전기화학회지
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• 제8권3호
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• pp.130-134
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• 2005

본 연구에서는 그동안 전기화학적으로 합성되지 못했던 III-V족 화합물 반도체 InSb를 구연산 용액으로부터 합성하였으며 자체 제조한 AAO를 나노템플릿으로 이용하여 정전압 도금을 실시하여 InSb 나노와이어를 제조하였다 제조된 InSb나노와이어는 X선 회절분석 결과 단결정의 나노와이어는 아니었으나 정확하게 화학양론을 만족시키는 화합물임을 확인하였고, 평판 박막 상태의 InSb와는 달리 나노와이어의 길이방향으로 (220) 방향의 결정이 주로 성장하는 우선결정방위를 가지고 있음을 알 수 있었다. 또한 집합적으로 배열된 상태에서 측정된 I-V특성 곡선에서는 n형 반도체의 특성을 보이되 밴드갭이 좁고, 전자이동도가 큰 InSb고유의 특성상 반금속과 유사한 전기적 특성을 보유하고 있음을 확인하였다.

• 한국전기전자재료학회논문지
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• 제21권11호
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• pp.968-972
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• 2008

Ni/Ti/Al multilayer system ('/'denotes the deposition sequence) was tested for low-resistance ohmic contact formation to Al-implanted p-type 4H-SiC. Ni 30 nm / Ti 50 nm / Al 300 nm layers were sequentially deposited by e-beam evaporation on the 4H-SiC samples which were implanted with Al (norminal doping concentration = $4\times10^{19}cm^{-3}$) and then annealed at $1700^{\circ}C$ for dopant activation. Rapid thermal anneal (RTA) temperature for ohmic contact formation was varied in the range of $840\sim930^{\circ}C$. Specific contact resistances were extracted from the measured current vs. voltage (I-V) data of linear- and circular transfer length method (TLM) patterns. In constrast to Ni contact, Ni/Ti/Al contact shows perfectly linear I-V characteristics, and possesses much lower contact resistance of about $2\sim3\times10^{-4}\Omega{\cdot}cm^2$ even after low-temperature RTA at $840^{\circ}C$, which is about 2 orders of magnitude smaller than that of Ni contact. Therefore, it was shown that RTA temperature for ohmic contact formation can be lowered to at least $840^{\circ}C$ without significant compromise of contact resistance. X-ray diffraction (XRD) analysis indicated the existence of intermetallic compounds of Ni and Al as well as $NiSi_{1-x}$, but characteristic peaks of $Ti_{3}SiC_2$, a probable narrow-gap interfacial alloy responsible for low-resistance Ti/Al ohmic contact formation, were not detected. Therefore, Al in-diffusion into SiC surface region is considered to be the dominant mechanism of improvement in conduction behavior of Ni/Ti/Al contact.

• 한국산학기술학회논문지
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• 제16권2호
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• pp.1026-1035
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• 2015

성공적인 신제품 개발을 위해서 디자인과 마케팅의 통합은 중요하지만, 두 영역이 통합할 때에 명확하게 어떠한 문제가 발생하고 실제로 어떠한 방법으로 문제가 해결되는지에 관한 논의는 많지 않다. 본 연구에서는 디자인과 마케팅이 통합될 때 발생하는 구체적인 문제와 실질적인 해결책을 알아내기 위하여, 미국의 한 대학교에서 디자인 학생들과 마케팅 학생들을 대상으로 진행된 2년간의 통합적 신제품 개발 수업에서 설문조사를 실시하였다. 65명의 조사 결과에 따르면 (1) 기능적 차이에 따른 갈등과 (2) 의사결정 권한의 불균형이 구체적인 문제점으로 발견되었고, 이러한 문제점들을 해결하기 위하여 (1) 의사소통을 강화하거나 (2) 의사소통을 단절하는 방법을 사용하는 것으로 드러났다. 본 연구의 결과가 가지는 디자인 마케팅 협업시의 통합 영역의 학문적 시사점을 정리해본다.

• 동력기계공학회지
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• 제18권4호
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• pp.23-28
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• 2014

In order to increase the performance of conventional hot water floor heating system, the bubble jet loop heat pipe for the system was developed. This experiment was conducted under next conditions : Working fluid was R-134a, charging ratio was 50%. A temperature of hot water, room temperature and flow rate were $60^{\circ}C$, $15^{\circ}C$ and 0.5~1.5 kg/min, respectively. The experimental results, show that bubble jet loop heat pipe had a high effective thermal conductivity of $4714kW/m^{\circ}C$ and a sufficient heat flux of $73W/m^2$ to heat the floor to $35^{\circ}C$ in case of the 1.5 kg/min of flow rate. So the bubble jet loop heat pipe has a possibility for appling of the floor heating system. Additionally, the visualization of bubble jet loop heat pipe was performed to understand the operating principle. Bubbles made by the narrow gap between inner tube and outer tube of evaporating part generate pulsation at liquid surface of working fluid. The pulsation had slug flow and wavy flow. So working fluid circulates in the bubble jet loop heat pipe as two phase flow pattern. And large amount of heat is transferred by the latent heat from evaporating part to condensing part.

• Tribology and Lubricants
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• 제30권6호
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• pp.337-342
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• 2014

The reduction of drag torque is an important research issue in terms of improving transmission efficiency. Drag torque in a wet clutch occurs because of the viscous drag generated by the transmission fluid in a narrow gap (clearance) between the friction plate and a separate plate. The objective of this paper is to observe the effects of the friction plate area and the clearance on the drag torque using finite element simulation. The two-phase flow of air and oil fluid is considered and modeled for the simulation. The simulation analysis reveals that as the rotational speed increases, the drag torque generally increases to a critical point and then decreases sharply at a high speed regime. The clearance between the two plates plays an important role in controlling drag torque peak. An increase in the clearance causes a decrease in shear stress; thus, the drag torque also decreases according to Newton's law of viscosity. An observation of the effect of the area of contact between transmission fluid and friction plate shows that the drag torque increases with the contact area. The flow vectors inside the flow channel present clear evidence that the velocity of the fluid flows is faster with a larger friction plate, that is, in the case of a larger contact area. Therefore, the optimum size of the friction plate should be determined carefully, considering both the clutch performance and drag reduction. It is expected that the results from this study can be very useful as a database for clutch design and to predict the drag torque for the initial design with respect to various clutch parameters.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.281.2-281.2
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• 2013

Since heavy metal ions included in water or food resources have critical effects on human health, highly sensitive, rapid and selective analysis for heavy metal detection has been extensively explored by means of electrochemical, optical and colorimetric methods. For example, quantum dots (QDs), such as semiconductor QDs, have received enormous attention due to extraordinary optical properties including high fluorescence intensity and its narrow emission peaks, and have been utilized for heavy metal ion detection. However, the semiconductor QDs have a drawback of serious toxicity derived from cadmium, lead and other lethal elements, thereby limiting its application in the environmental screening system. On the other hand, Graphene oxide (GO) has proven its superlative properties of biocompatibility, unique photoluminescence (PL), good quenching efficiency and facile surface modification. Recently, the size of GO was controlled to a few nanometers, enhancing its optical properties to be applied for biological or chemical sensors. Interestingly, the presence of various oxygenous functional groups of GO contributes to opening the band gap of graphene, resulting in a unique PL emission pattern, and the control of the sp2 domain in the sp3 matrix of GO can tune the PL intensity as well as the PL emission wavelength. Herein, we reported a photoluminescent GO array on which heavy metal ion-specific DNA aptamers were immobilized, and sensitive and multiplex heavy metal ion detection was performed utilizing fluorescence resonance energy transfer (FRET) between the photoluminescent monolayered GO and the captured metal ion.