• 한국세라믹학회지
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• 제53권5호
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• pp.563-567
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• 2016

The structural properties of $HfO_2$ films could be improved by thermal treatment owing to their crystallization. We deposited $HfO_2$ films on sapphire by radio frequency (RF) magnetron sputtering, whose base vacuum pressure was lower than $4.5{\times}10^{-6}$ Pa, RF power was 100 W, working temperature was $200^{\circ}C$, working pressure was 3 mTorr, and the density of the active gas (Argon) was 20 sccm. After depositing the $HfO_2$ films, the samples were thermally treated by rapid thermal annealing (RTA) in $O_2$ ambient at different temperatures. Subsequently, the measured physical properties (structural, morphological, and optical) indicated that the crystallite size, refractive index at a wavelength of 632 nm, and packing density increased with rising temperatures. In particular, an $HfO_2$ film thermally treated at $800^{\circ}C$ in $O_2$ ambient had the highest refractive index of 2.0237 and packing density of 0.9638. The relation between optical and structural properties was also analyzed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.207.2-207.2
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• 2013

Oxide-based thin film transistors have been attempted as powerful candidates for driving circuits for active-matrix organic light-emitting diodes and transparent electronics. The oxide TFTs are based on the amorphous multi-component oxides involving zinc, indium, and/or tin elements as main cation sources. The current work employed RF sputtering in order to deposit zinc-tin oxide thin films applicable to transparent oxide thin film transistors. The deposited thin film was characterized and probed in terms of materials and devices. The physical/chemical characterizations were performed using X-ray diffraction, Atomic Force Microscopy, Spectroscopic Ellipsometry, and X-ray Photoelectron Spectroscopy. The thin film transistors were fabricated using a bottom-gated structure where thermally-grown silicon oxide layers were applied as gate-dielectric materials. The inherent properties of oxide thin films are combined with the corresponding device performances with the aim to fabricating the multi-component oxide thin films being optimized towards transparent electronics.

• 한국군사과학기술학회지
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• 제24권3호
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• pp.317-327
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• 2021

Low Frequency Active Sonobuoy(hereinafter referred to as LFAS) are being developed in Korea in consideration of compatibility with existing overseas sonobuoys, and a communication device for acoustic signals receiving and operating control of LFAS has been developed. The communication device needs to verify compatibility with the existing Sonobuoy, and for this purpose, the standardized Sonobuoy communication protocol was applied. The communication device is designed/manufactured to transmit the acoustic signal received in real time from the Sonobuoy through VHF band RF communication to the data processing device, and transmit CFS/CSG commands for operation control to the Sonobuoy through UHF band RF communication. In order to verify the manufactured communication device, the communication status and performance were verified by interlocking test through Ultra Electronics' PASS-II equipment and domestically developed electronic device of Sonobuoy. In addition, operability was verified through environmental tests, water tanks, and marine operations. In the future, the communication device of sonobuoy can be used for verification of the Sonobuoy developed in Korea.

• ETRI Journal
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• 제26권3호
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• pp.229-240
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• 2004

This paper reports on our development of a dual-mode transceiver for a CMOS high-rate Bluetooth system-onchip solution. The transceiver includes most of the radio building blocks such as an active complex filter, a Gaussian frequency shift keying (GFSK) demodulator, a variable gain amplifier (VGA), a dc offset cancellation circuit, a quadrature local oscillator (LO) generator, and an RF front-end. It is designed for both the normal-rate Bluetooth with an instantaneous bit rate of 1 Mb/s and the high-rate Bluetooth of up to 12 Mb/s. The receiver employs a dualconversion combined with a baseband dual-path architecture for resolving many problems such as flicker noise, dc offset, and power consumption of the dual-mode system. The transceiver requires none of the external image-rejection and intermediate frequency (IF) channel filters by using an LO of 1.6 GHz and the fifth order onchip filters. The chip is fabricated on a $6.5-mm^{2}$ die using a standard $0.25-{\mu}m$ CMOS technology. Experimental results show an in-band image-rejection ratio of 40 dB, an IIP3 of -5 dBm, and a sensitivity of -77 dBm for the Bluetooth mode when the losses from the external components are compensated. It consumes 42 mA in receive ${\pi}/4-diffrential$ quadrature phase-shift keying $({\pi}/4-DQPSK)$ mode of 8 Mb/s, 35 mA in receive GFSK mode of 1 Mb/s, and 32 mA in transmit mode from a 2.5-V supply. These results indicate that the architecture and circuits are adaptable to the implementation of a low-cost, multi-mode, high-speed wireless personal area network.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.360-360
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• 2012

Zn-Sn-O (Zinc-Tin-Oxide; ZTO) thin films have been gaining extensive academic and industrial attentions owing to a semiconducting channel materials applicable to large-sized flat-panel displays. Due to the constituent oxides i.e., ZnO and SnO2, the resultant Zn-Sn-O thin films possess artificially controllable bandgaps and transmittances especially effective in the visible regime. The current approach employed RF sputtering in depositing the Zn-Sn-O thin films onto glass substrates at ambient conditions. This work places its main emphases on the electrical/optical features which are closely related to the combinations of processing variables. The electrical characterizations are performed using dc-based current-voltage characteristics and ac-based impedance spectroscopy. The optical constants, i.e., refractive index and extinction coefficient, are calculated through spectroscopic ellipsometry along with the estimation of bandgaps. The charge transport of the deposited ZTO thin films is based on electrons characteristic of n-type conduction. In addition to the basic electrical/optical information, the delicate manipulation of n-type conduction is indispensible in diversifying the industrial applications of the ZTO thin films as active devices in information and energy products. Ultimately, the electrical properties are correlated to the processing variables along with the underlying mechanism which largely determines the electrical and optical properties.

• The Korean Journal of Pain
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• 제13권2호
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• pp.196-201
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• 2000

Background: Currently, minimally invasive operations are preferred to open surgery whenever possible. Lumbar sympathectomy using RF (radiofrequency) thermocoagulation is both safe and minimally invasive. The problem with the technique is that it cannot be performed successfully in a significant number of cases. If the temperature change in the sole is monitored immediately after the procedure then it can be determined if the procedure needs to be repeated. Methods: A curved tip cannula, 150 mm long with a 10 mm active tip, was used for RF lumbar sympathectomy. The temperature of the soles of both the foot on the affected side and the foot on the control side was monitored immediately before the procedure, immediately after making the L2 lesion, immediately after making the L3 lesion and at 5, 10, and 15 minutes after the procedure. Results: No statistically significant difference was observed in the temperature of the two soles before making the lesions. In the 24 of the 27 patients, there were prominent differences in temperature between the two soles at 10 minutes after the procedures. 11 of the 24 patients showed a significant temperature change after the first trial. But the remaining 13 required a second lesion on L2 and L3. Conclusions: We judged the success of the operation in the operating room by monitoring the temperature difference in the soles of the feet. When no increase in the temperature difference is observed, we can move the electrode and make another lesion. With this procedure, we can drastically increase the success rate of the procedure.

• Applied Biological Chemistry
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• 제19권1호
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• pp.24-30
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• 1976

갈대(Phragmites communis Trin.)의 지하경(地下莖)을 암소(暗所)에서 3일간 기른 싹의 메타놀 추출물(抽出物)을 TLC로 분리동정(分離同定)하였으며, 아래와 같은 결과를 얻었다. 1. 검정(檢定)된 화합물은 주(主)로 indole amine류(類)였으며, serotonin, tryptamine, tryptophan등은 표준화합물과의 co-chromatography에 의해 동정되었고, 용매계를 달리하여 구한 Rf치 및 발색특성을 문헌과 비교하여 추정한 것으로는 bufotenine, N-methylserotonin, N,N-dimethyltryptamine이었으며, Skatole 및 gramine의 존재(存在)의 가능성도 추측(推測)되었다. 2. 갈대 생육의 일정기간 동안 indole 화합물의 methyl화(化) 및 hydroxyl화(化) 대사계(代謝系)의 활성(活性)이 강하게 나타나고 있다고 생각된다. 3. 본 실험에서 처음 시도된 "overlap"점적(點滴)법을 사용한 TLC방법(方法)은 시료중의 방해물질(妨害物質)의 영향으로 시료와 표준품 간에 동일 화합물(化合物)이 Rf치에 차이(差異)를 나타낼 때 시료중의 동일(同一) 화합물의 검정에 유용한 방법이 될 것이다.

• 한국전기전자재료학회논문지
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• 제25권6호
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• pp.439-444
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• 2012

For the application of photo-detector as active layer, we have studied how to deposit SiGe thin film using an independent Si target and Ge target, respectively. Both targets were synthesized by purity of 99.999%. Plasma generators were generated by radio frequency (rf, 13.56 MHz) and direct current (dc) power. When Ge and Si targets were sputtered by dc and rf power, respectively, we could observe the growth of highly crystalline Ge thin film at the temperature of $400^{\circ}C$ from the result of raman spectroscopy and X-ray diffraction method. However, SiGe thin film did not deposit above method. Inversely, we changed target position like that Ge and Si targets were sputtered by rf and dc power, respectively. Although Ge crystalline growth without Si target sputtering deteriorated considerably, the growth of SiGe thin film was observed with increase of Si dc power. SiGe thin film was evaluated as microcrystalline phase which included (111) and (220) plane by X-ray diffraction method.

• 마이크로전자및패키징학회지
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• 제7권3호
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• pp.31-36
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• 2000

RF(radio Frequency)용 MCM(Multichip Module)-D 기판 내장형 인덕터를 개발하였다. MCM 기술은 고밀도 패키징 기술로서 주로 디지털회로에 많이 적용되어 왔으나, 최근에는 아날로그회로 및 디지털회로가 혼재된 혼성신호 및 초고주파 회로에도 적용되고 있다. 혼성신호에서는 능동소자 주변에 많은 수의 수동소자가 연결되므로 MCM-D 기판에 수동소자를 내장시키면 원가절감과 시스템의 크기 축소 및 경량화를 이를 수 있을 뿐 아니라, 성능과 신뢰성을 향상시킬 수 있다. 본 논문에서 MCM-D 기판은 Cu/감광성 BCB(Benzocyclobutene)를 각각 금속배선 및 절연막 재료로 사용하였고, 금속배선은 Ti/Cu를 각각 1000 $\AA$/3000 $\AA$으로 스퍼터한 후 fountain 방식으로 전기 도금하여 3 $\mu\textrm{m}$ Cu를 형성하였으며, 인덕터는 coplanar구조로 하여 기존의 반도체 공정을 이용하여 MCM-D기판에 인덕터를 안정적으로 내장시키고 전기적 특성을 측정하였다.

• 한국전자파학회논문지
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• 제11권1호
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• pp.84-92
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• 2000

2.4 GHz 대역 WLL 단말기용 GaAs MESFET MMIC 송신기를 설계하고 제작하였다. 설계된 송신기는 이중 평형 능동형 혼합기와 전압 부궤환 구조를 갖는 2단 구동증폭기로 구성하였다. 특히, 한 쌍의 소스 접지-게이트 접지(Common-Source. Common -Gate: CSCG) 구조를 사용하여 IF 입력 선호의 비대칭성으로 인한 동작영역 감소를 보상하였다. 또한 MESFET의 단자간 위상 특성을 이용하여 국부 발진기(La) 신호의 누설 전력을 억제 하였다. 제작된 칩의 크기는 $0.75\times1.75 mm^2$이었고 측정 결과 2.7 V. 55.2 mA에서 386 dB의 변환이득. 11.6 dBm 의 출력$P_{idB}$ 구동증폭기의 RF 출력 -5dBm에서 - 31.5 dBc의 IMD3의 특성을 얻었다. 따라서 제작된 송신기는 WLL 단말기에 적용 가능하다.