• 한국약용작물학회지
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• 제15권2호
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• pp.100-104
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• 2007

A protocol for the production of transgenic Panax ginseng C.A. Meyer was established via Agrobacterium tumefaciens-mediated genetic transformation of direct somatic embryos. A number of conditions related to the co-cultivation were tested with respect to maximizing transformation efficiency. The results showed that pH of the co-cultivation medium (5.7), the bacterial growth phase (optical density; $OD_{600}$ = 0.8), co-cultivation period (3 days), and acetosyringone concentration $(100\;{\mu}M)$ had positive effects on transformation. Selected plantlets were cultured on the medium at an elevated hygromycin level(30 mg/l). Integration of the transgenes into the P. ginseng nuclear genome was confirmed by PCR analysis using hpt primers and by Southern hybridization using hpt-specific probe. The transgenic plantlets were obtained after 3-month cultivation and did not show any detectable variation in morphology or growth characteristics compared to wild-type plants.

• 대한전자공학회논문지SD
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• 제44권3호
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• pp.20-25
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• 2007

본 논문에서는 $LiNbO_3$의 선택적 영역을 도메인 반전을 수행하였으며, 이를 대역변조기 및 SSB 광변조기 제작에 응용하였다. 인가전압에 대한 회로적인 응답전류를 분석 및 고려함으로써 도메인 벽의 이동속도를 정확히 제어할 수 있었다. 과도한 도메인의 벽 이동속도에 의한 도메인 반전 형상을 확인하였고, 또한 도메인 벽의 진행방향에 따라 그 속도의 차이가 발생함을 알 수 있었다. 제작된 대역변조기는 30.3 GHz를 중심주파수로 하여 5.1GHz의 3dB 대역폭을 보였고. SSB 광변조기의 변조 스펙트럼으로부터 19dBm의 5.8GHz RF 입력신호에 대해 USB가 LSB에 비해 33dB정도 억제됨을 확인할 수 있었다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제17권4호
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• pp.483-491
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• 2017

The interdigitated germanium (Ge) meta-lsemiconductor-metal (MSM) photodetectors (PDs) with and without an $SiO_2$ anti-reflection (AR) layer was fabricated, and the effect of $SiO_2$ AR layer on their optoelectronic response properties were investigated in detail. The lowest reflectance of 15.6% at the wavelength of 1550 nm was obtained with a $SiO_2$ AR layer with a thickness of 260 nm, which was in a good agreement with theoretically calculated film thickness for minimizing the reflection of Ge surface. The Ge MSM PD with 260 nm-thick $SiO_2$ AR layer exhibited enhanced device performance with the maximum values of responsivity of 0.65 A/W, the quantum efficiency of 52.2%, and the detectivity of $2.49{\times}10^9cm\;Hz^{0.5}W^{-1}$ under the light illumination with a wavelength of 1550 nm. Moreover, time-dependent switching analysis of Ge MSM PD with 260 nm- thick $SiO_2$ AR layer showed highest on/off ratio with excellent stability and reproducibility. All this investigation implies that 260 nm-thick $SiO_2$ AR layer, which is effective in the reduction in the reflection of Ge surface, has a great potential for Ge based optoelectronic devices.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2396-2400
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• 2007

Transparent In-doped (1 at.%) zinc oxide (IZO) thin films are deposited by pulsed DC magnetron sputtering with H2 mixed Ar atmosphere on glass substrate without any heating process. Even at room temperature, highly c-axis oriented IZO thin films were grown in perpendicular to the substrate. The hydrogenated IZO (IZO:H) film isolated in H2 atmosphere for 30 min exhibited an average optical transmittance higher than 85% and low electrical resistivity of less than 2.7 × 10?3 Ω·cm. These values are comparable with those of commercially available ITO. Each of the IZO films was used as an anode contact to fabricate organic light-emitting diodes (OLEDs) and the device performances studied. At the current density of 1 × 103 A/m2, the OLEDs with IZO:H (H2) anode show excellent efficiency (11 V drive voltage) and a good brightness (8000 cd/m2) of the light emitted from the devices, which are as good as the control device built on a commercial ITO anode.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2241-2247
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• 2007

A new series of chiral bent-shaped liquid crystals with an asymmetric central core based on 1,6- dihydroxynaphthalene and chiral terminal chain prepared from (S)-(?)-2-methyl-1-butanol, 1,6-naphthalene bis[4-(4-alkoxyphenyliminomethyl)]benzoates [N(1,6)-n-O-PIMB(n-2)*-(n-4)O (n = 8-11)] were synthesized. Their mesomorphic properties and phase structures were investigated by means of electro-optical, polarization reversal current, and second harmonic generation measurements in order to confirm the relationship between the molecular structure and phase structure. All odd n (n = 9 and 11) compounds, N(1,6)-9-O-PIMB7*-5O and N(1,6)-11-O-PIMB9*-7O exhibit antiferroelectric phase, whereas even n (n = 8 and 10) compounds was flexible, N(1,6)-10-O-PIMB8*-6O exhibits the ferroelectric phase but N(1,6)-8-O-PIMB6*-4O exhibits the antiferroelectric phase. These results come from the decrease of the closed packing efficiency within a layer and the lack of uniform interlayer interaction between adjacent layers, which were caused by the asymmetrical naphthalene central core. Thus, we concluded that the structure of central core as well as the terminal chain plays an important role for the emergence of particular polar ordering in phase structures.

• 한국세라믹학회지
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• 제43권3호
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• pp.169-172
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• 2006

We have synthesized a $Eu^{2+}-activated\;{(Sr,Ba)}_2SiO_4$ yellow phosphor and investigated the development of blue LEDs by combining the phosphor with a InGaN blue LED chip (${\lambda}_{em}$=405 nm). The InGaN-based ${(Sr,Ba)}_2SiO_{4}:Eu$ LED lamp shows two bands at 405 nm and 550 nm. The 405 nm emission band is due to a radiative recombination from a InGaN active layer. This 405 nm emission was used as an optical transition of the ${(Sr,Ba)}_2SiO_{4}:Eu$ phosphor. The 550 nm emission band is ascribed to a radiative recombination of $Eu^{2+}$ impurity ions in the ${(Sr,Ba)}_2SiO_4$ host matrix. In the preparation of UV Yellow LED Lamp with ${(Sr,Ba)}_2SiO_{4}:Eu$ yellow phosphor, the highest luminescence efficiency was obtained at the epoxy-to-yellow phosphor ratio of 1:0.45. At this ratio, the CIE chromaticity was x=0.4097 and y=0.5488.

• 대한전자공학회논문지TC
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• 제40권12호
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• pp.27-37
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• 2003

다양한 실시간 멀티미디어 서비스들을 전송하는 DWDM(Dense-Wavelength Division Multiplexing) 기반의 차세대 인터넷에서는 DWDM망의 다양한 QoS(Quality of Service) 파라미터들을 복합적으로 고려하는 QoS RWA(Routing and Wavelength Assignment) 방식으로의 접근이 요구되어진다. 그러나 일반적으로 다중 제약조건을 만족하는 최적의 경로를 찾는 것은 NP-complete한 문제로서, 파장 연속성가지 고려해야 하는 DWDM 망에서는 QoS RWA 분야에 대한 연구가 아직 미비한 실정이다. 따라서 본 논문에서는 QoS RWA 수행하기 위한 방안으로 flooding 기법을 확장하여 경로 설정에 대한 계산과 구현을 간소화시킨 QPR(Qualified Path Routing) 알고리즘을 제안한다. 또한 QPR 알고리즘을 기반으로 광신호 품질, 광자원(파장), 생존성 및 파장 연속성까지 고려하여 차등적인 QoS 지원하는 QoS-based RWA 알고리즘을 제안하며, 블록률, 라우팅 오버헤드 및 생존성 측면의 성능 평가를 통해 제안된 알고리즘들의 효율성을 검증하였다.

• 한국정보통신학회논문지
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• 제14권1호
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• pp.191-196
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• 2010

본 연구에서는 타겟 제작에 드는 비용을 줄이고, 타겟 이용의 효율성을 높이기 위해 기존의 소결된 세라믹 타겟 대신 분말 타겟으로 사용하여 알루미늄 도핑된 산화아연(Aluminum doped zinc oxde; AZO)박막을 마그네트론 스퍼터법에 의해 제조하고, 스퍼터 압력에 따른 박막 물성을 조사하였다. 유리 기판에 증착된 AZO 박막은 타깃 종류 및 스퍼터 압력에 관계없이 기판에 수직한 c-축 방향으로 우선 성장방위를 갖는 hexagonal 구조로 성장되었다. 스퍼터 압력이 증가함에 따라 이 면 방향으로의 결정성장이 촉진되었다. AZO 박막의 전기적, 광학적 특성은 스퍼터 압력 증가에 따라 향상되었으며, 15 mTorr에서 $6.5{\times}10^{-1}\;{\Omega}-cm$의 최소의 비저항 값을 나타내었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.1100-1109
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• 2006

In this study, two different technologies which can measure temperature simultaneously at many points are introduced. One is to use a thermal sensor cable that is comprised of addressable thermal sensors connected in parallel within a single cable. The other is to use an optic fiber with Distributed Temperature Sensing (DTS) system. The difference between two technologies can be summarized as follows. A thermal sensor cable has a concept of 'point sensing' that can measure temperature at accurate position of a thermal sensor. So the accuracy and resolution of temperature measurement are up to the ability of the thermal sensor. Whereas optic fiber sensor has a concept of 'distributed sensing' because temperature is measured by ratio of Stokes and anti-Stokes component intensities of Raman backscatter that is generated when laser pulse travels along an optic fiber. It's resolution is determined by measuring distance, measuring time and spatial resolution. The purpose of this study is that application targets of two temperature measurement techniques are checked in technical and economical phases by examining the strength and weakness of them. Considering the functions and characteristics of two techniques, the thermal sensor cable will be suitable to apply to the assessment of groundwater flow, geothermal distribution and grouting efficiency within 300m distance. It is expected that the optic fiber sensor can be widely utilized at various fields (for example: pipe line inspection, tunnel fire detection, power line monitoring etc.) which need an information of temperature distribution over relatively long distance.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.159-159
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• 2010

We conducted bum-in test by current stress to evaluate acceleration reliability characteristics about p-resistivity influence of GaN-based light-emitting diodes. The LEDs used in this study are the polarization field-induced LED(PF-LED) having low p-resistivity and the highly resistive LED(HR-LED) having high p-resistivity. The result of high stress experiment shows that current crowding phenomenon is occurred from the center of between p-bonding pad and n-bonding pad to either electrodes. In addition, series resistance and optical power decrease dramatically. These results means that the resistance of between p-bonding pad and p-GaN affect reliability. That's why we need to consider the ohmic contact of p-bonding pad when design the high efficiency and high reliability LEDs.