• 한국반도체및디스플레이장비학회:학술대회논문집
• /
• 한국반도체및디스플레이장비학회 2002년도 추계학술대회 발표 논문집
• /
• pp.85-90
• /
• 2002

$RuO_2$/GaN and related contacts were investigated for Schottky contacts in GaN-Based optical and electronic devices. We demonstrated that an $RuO_2$ film forms a stable Schottky contact on a GaN layer with a barrier height (${\Phi}_B$) of 1.46 eV and transmittance of 70% in the visible and near UV region. $RuO_2$/GaN Schottky diode showed a breakdown at over -50V and leakage current of only 0.3 nA at -5V. The $RuO_2$/GaN Schottky type photodetector had the UV/Visible rejection ratio of over $10^5$ and the responsivity of 0.23 A/W at 330 nm. The $RuO_2$ gate AlGaN/GaN EFET exhibited high drain current ($I_d$) of 689.3 mA/mm and high transconductance ($g_m$) of 197.4 mS/mm. Cut-Off frequency ($f_t$) and maximum operating frequency ($f_{max}$) were measured as 27.0 GHz and 45.5 GHz, respectively.

• 한국컴퓨터정보학회논문지
• /
• 제21권9호
• /
• pp.79-84
• /
• 2016

In this paper we consider the problem of finding the triplet (S,${\pi}$,f), where $S{\subseteq}V$, ${\pi}$ is a sequence of nodes in S and $f:V{\backslash}S{\rightarrow}S$ for a given complete graph G=(V,E). In particular, there exist two costs, $c^V_{uv}$ and $c^D_{uv}$ for $(u,v){\in}E$, and the cost of triplet (S,${\pi}$,f) is defined as $\sum_{i=1}^{{\mid}S{\mid}}c^V_{{\pi}(i){\pi}(i+1)}+2$ ${\sum_{u{\in}V{\backslash}S}c^D_{uf(u)}$. This problem is motivated by the integrated routing of the vehicle and drone for urban delivery services. Since a well-known NP-complete TSP (Traveling Salesman Problem) is a special case of our problem, we cannot expect to have any polynomial-time algorithm unless P=NP. Furthermore, for practical purposes, we may not rely on time-exhaustive enumeration method such as branch-and-bound and branch-and-cut. This paper suggests the simple heuristic which is motivated by the MST (minimum spanning tree)-based approximation algorithm and neighborhood search heuristic for TSP.

• 폴리머
• /
• 제32권3호
• /
• pp.256-262
• /
• 2008

폴리아믹산(PAA)의 열 이미드화 반응을 이용해서 4,4'-(hexafluoroisopropylidene)diphthalic anhydride(6FDA)와 bis[4-(3-aminophenoxy)phenyl]sulfone(BAFS)의 단량체에 2,2-bis[4-(4-amino-phenoxy)phenyl]hexafluoropropane(BAPP)의 다양한 몰 비에 따른 삼불소메틸($CF_3$) 곁가지를 가지는 공중합체 폴리이미드(PI)를 합성하였다. 이 공중합체 PI는 N,N'-dimethylacetamide(DMAc)와 같은 용매에 잘 녹았으며 용액 캐스팅하여 얻은 필름은 유연하고 질긴 성질을 보였다. 공중합체 PI 필름의 열적-기계적 성질, 모폴로지 및 광학 투명도들을 측정하기 위해 시차 주사 열 분석기(DSC)와 열 중량 분석기(TGA), 넓은 각 X-선 회절도(XRD), 주사 전자현미경(SEM), 만능 인장 시험기(UTM) 그리고 자외선-가시광선 흡광도기(UV-Vis. spectrometer) 등을 사용하였다. 얻은 공중합체 PI 필름은 투명하였으며, 각 필름의 cut-off wavelength(${\lambda}_0$)은 $275{\sim}319\;nm$이었고, 노란색 지수(yellow index: YI)는 $3.65{\sim}10.37$의 값을 보여주었다. 공중합체 PI 필름의 열적-기계적 성질들은 BAPP의 몰비가 증가할수록 증가하였지만, 광학적 특성에서는 반대의 결과를 보여주었다.

• 분석과학
• /
• 제15권1호
• /
• pp.72-79
• /
• 2002

Di-(2-ethylhexyl)phthalate (DEHP) 가 가소제로 첨가되 있는 poly(vinylchloride) (PVC) 제품의 사용중에는 DEHP가 방출되어 나올 가능성이 있다. 이때 추출되는 DEHP의 정량적인 측정법에는 여러가지가 있으나 그 방법에 따라 용출량에 많은 차이가 발생하기 때문에 측정방법과 결과에 대한 비교분석은 시급한 과제라 할 수 있다. 이를 평가하기 위하여 PVC를 주원료로 하는 혈액백과 수액백에서의 DEHP 용출에 관한 연구를 기체 크로마토그래프와 분광광도계를 이용한 두 가지 방법으로 수행하였다. 5종류의 PVC 백을 실험 재료로 선택하여 $40{\times}10{\times}0.4mm$ 크기의 시편을 제조하고 이를 용출액에 담가 1시간동안 DEHP를 용출하였다. 기체 크로마토그래프로 DEHP 를 검출한 결과 시료에 따라 $23.2{\sim}70.9{\mu}g/mL$ 의 DEHP가 용출되는 것을 알 수 있었다. 반면 PVC백 안에 용출액을 주입하여 1시간 동안 DEHP를 용출시키고 분광 광도계를 이용하여 DEHP를 검출한 결과 $24.8{\sim}41.3{\mu}g/mL$의 DEHP가 용출되었다. 용출 조건과 실험방법에 따라 서로 다른 수치를 보임을 알 수 있었고 단위 시간 단위 면적 당 용출되는 DEHP의 양은 일정하다는 전제 하에 두 실험의 결과를 비교하고 환산하는 식을 구하여 적용한 결과 두 측정방법에서 얻어진 용출량이 거의 일치하였다.

• 센서학회지
• /
• 제12권2호
• /
• pp.66-71
• /
• 2003

Pt/AlGaN Schottky-type UV photodetectors were designed and fabricated. A low-temperature AlGaN interlayer buffer was grown between the AlGaN and GaN film in the diode structure epitaxy to obtain crack-free AlGaN active layers. A comparison was then made of the structural, electrical, and optical characteristics of two different diodes: one with an AlGaN($0.5\;{\mu}m$)/n+-GaN(2 nm) structure (type 1) and the other with an AlGaN($0.5\;{\mu}m$)/AlGaN interlayer($150\;{\AA}$)/n+-GaN($3\;{\mu}m$) structure(type 2). A crack-free AlGaN film was obtained by the insertion of a low-temperature AlGaN interlayer with an aluminum mole fraction of 26% into the $Al_xGa_{1-x}N$ layer. The fabricated Pt/$Al_{0.33}Ga_{0.67}N$ photodetector had a leakage current of 1 nA for the type 1 diode and $0.1\;{\mu}A$ for the type 2 diode at a reverse bias of -5 V. For the photoresponse measurement, the type 2 diode exhibited a cut-off wavelength of 300 nm, prominent responsivity of 0.15 A/W at 280 nm, and UV-visible extinction ratio of $1.5{\times}10^4$. Accordingly, the Pt/$Al_{0.33}Ga_{0.67}N$ Schottky-type ultraviolet photodetector with an AlGaN interlayer exhibited superior electrical and optical characteristics and improved UV detecting properties.

• 한국재료학회지
• /
• 제17권12호
• /
• pp.676-681
• /
• 2007

According to progress rapidly digitalization, networked and mobilization of electronics industry, there are demands for being smaller, thinner, more light, and more efficient complex functions of electronic devices which are wireless devices, semi-conductors, packages and mobile devices. Therefore, the solder resist on a printed circuit board have been required with the high resolution and the eco-friendly materials in the surface treatments such as high heating process and coating process with electrolysis. In this study, the photoinitiator initiator and monomers of the solder resist were prepared with their contents for reducing the occurrence of the under-cut. We investigated the sample surface by UV/VIS spectrometer, FT-IR, OM after HASL and ENIG process. From our results, it is possible to get a high adhesion of resist with optimal contents between the photoinitiator initiator and monomers after surface treatments.

• 한국의류산업학회지
• /
• 제11권4호
• /
• pp.641-647
• /
• 2009

The purpose of this study was to evaluate the physical properties and handle of knitwears made with silver yarns. The four different knitted fabrics were made and compared: cotton(C), cotton/silver(CS), polyester(P), and polyester/silver(PS). If fabrics knitted with silver combined yarns, their electrical shield properties, UV-cut properties, anti-static properties, and air permeability were improved. As an additional effect this also improves the antibacterial properties of fabrics. It was found that overall physical properties and functional properties were improved by using silver yarn with cotton. The silver knitted fabric was found to be improved its softness and fullness hand for apparel.

• 제어로봇시스템학회논문지
• /
• 제14권8호
• /
• pp.767-773
• /
• 2008

This paper presents a localization system based on the use of electric compass and tracking IR light source. Digital RGB(Red, Green, Blue)signal of digital CMOS Camera is sent to CPLD which converts the color image to binary image at 30 frames per second. CMOS camera has IR filter and UV filter in front of CMOS cell. The filters cut off above 720nm light source. Binary output data of CPLD is sent to DSP that rapidly tracks the IR light source by moving Camera tilt DC motor. At a robot toward north, electric compass signals and IR light source angles which are used for calculating the data of the location system. Because geomagnetic field is linear in local position, this location system is possible. Finally, it is shown that position error is within ${\pm}1.3cm$ in this system.

• 대한화장품학회지
• /
• 제25권4호
• /
• pp.43-50
• /
• 1999

The planarized $SiO_2$ particles were prepared by two-step reduction method of making much smaller particles, micron-sized ones, to improve spreadability, adherence, and smoothness. Various pigments known as flaky extender usually have terrace layers on their surfaces, but $SiO_2$ particles in this study exhibit a smooth surface structure. These single $SiO_2$ particles were used as core particles to prepare the composite particles coated with ultra fine $TiO_2$ particles by a homogeneous precipitation method. The thickness and the morphology of the deposited $TiO_2$ layers could be modified by adjusting the reactant concentrations, the reaction time and the temperature. The characteristics of $SiO_2/TiO_2$ composite in the field of color cosmetics are to give an UV-cut effect and to enhance the chroma of human skin color, one of optical properties.

• 대한화장품학회:학술대회논문집
• /
• 대한화장품학회 1999년도 IFSCC . ASCS 학술대회 발표 논문
• /
• pp.43-50
• /
• 1999

The planarized SiO$_2$ particles were prepared by two-step reduction method of making much smaller particles, micron-sized ones, to improve spreadability, adherence, and smoothness. Various pigments known as flaky extender usually have terrace layers on their surfaces, but SiO$_2$ particles in this study exhibit a smooth surface structure. These single SiO$_2$ particles were used as core particles to prepare the composite particles coated with ultra fine TiO$_2$ particles by a homogeneous precipitation method. The thickness and the morphology of the deposited TiO$_2$ layers could be modified by adjusting the reactant concentrations, the reaction time and the temperature. The characteristics of SiO$_2$/TiO$_2$ composite in the field of color cosmetics are to give an UV-cut effect and to enhance the chroma of human skin color, one of optical properties.