• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.1
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• pp.39-46
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• 2014

In this paper, to operate 2.4 GHz Inverted-L antenna with On-Board Broadband characteristics is proposed. The antenna was designed on the system board, the bandwidth by adjusting the reactance of the antenna that was formed common-mode and differential-mode on the antenna stubs has been improved. The system size is $80mm{\times}60mm$, the size of the antenna was limited to $30mm{\times}60mm$, the thickness of FR4 dielectric substrate is 0.8 mm, FR4 dielectric constant 4.4 is used. The experimental results, the bandwidth from 17.2 to 24.1 %, the gain is 3.01~4.71 dB, omni-directional radiation pattern characteristics were obtained. By a mobile terminal design applying the results of the paper, the handset's price competitiveness and production efficiency can be improved.

• Journal of Sensor Science and Technology
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• v.8 no.5
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• pp.421-426
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• 1999

In this paper, we present p-channel GaAs MOSFET having $Al_2O_3$ as gate insulator fabricated on a semi-insulating GaAs substrate, which can be operated in the depletion mode. $1\;{\mu}m$ thick undoped GaAs buffer layer, $4000\;{\AA}$ thick p-type GaAs epi-layer, undoped $500{\AA}$ thick AlAs layer, and $50\;{\AA}$ thick GaAs cap layer were subsequently grown by molecular beam epitaxy(MBE) on (100) oriented semi-insulating GaAs substrate and this wafer was oxidized. AlAs layer was fully oxidized as a $Al_2O_3$ thin film. The I-V, $g_m$, breakdown charateristics of the fabricated GaAs MOSFET showed that wet thermal oxidation of AlAs/GaAs epilayer/S I GaAs was successful in realizing depletion mode p-channel GaAs MOSFET.

• Journal of IKEEE
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• v.20 no.2
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• pp.152-162
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• 2016

Electrical resistivity tomography (ERT) is a technique to reconstruct the internal resistivity distribution using the measured voltages on the surface electrodes. ERT inverse problem suffers from ill-posedness nature, so regularization methods are used to mitigate ill-posedness. The reconstruction performance varies depending on the type of regularization method. In this paper, an interacting dual-mode regularization method is proposed with two different regularization methods, L1-norm regularization and total variation (TV) regularization, to achieve robust reconstruction performance. The interacting dual-mode regularization method selects the suitable regularization method and combines the regularization methods based on computed mode probabilities depending on the actual conditions. The proposed method is tested with numerical simulations and the results demonstrate an improved reconstruction performance.

• Journal of Navigation and Port Research
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• v.33 no.6
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• pp.409-414
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• 2009

As Korea has the economic structure heavily depending on exporting commodities, the importance of both maritime and air transportation mode is significant. Accordingly, for the sustainable and stable export the freight transportation market by mode needs to be developed complementarity each other. This paper, therefore, aims at analysing the LCL commodities transported by the two mode in terms of unit price, freight charge bearability and price structure. For this around 500 bill of lading(B/L) are collected and analysed resulting in deriving the distinctive characteristics of commodities by mode and the implication for price policy.

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.149-157
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• 2004

We have calculated the power extraction efficiency and the lasing wavelength distribution of complex-coupled(CC) DFB lasers above threshold for various｜$\chi$L｜ and facet reflectivity combinations, and we have compared the results with those at threshold. Also, we have investigated the effect of coupling coefficient ratio(CR) and the reflectivity of AR facet on the power extraction efficiency and the lasing wavelength distribution. At threshold, the single mode yield as a function of power extraction efficiency of in-phase(IP) CC DFB lasers is the same as that of anti-phase(AP) CC DFB lasers. Above threshold, however, the single mode yield as a function of power extraction efficiency of IP CC DFB lasers is much larger than that of AP CC DFB lasers. For IP CC DFB lasers, AR-HR combination has high single mode yield and large power extraction efficiency compared to other facet combinations. IP CC DFB laser with AR-HR combination for ｜$\chi$L｜of 0.8 has the highest single mode yield and largest power extraction efficiency above threshold among the cases considered. For AR-HR combination, as CR increases and the reflectivity of AR facet decreases, both single mode yield and power extraction efficiency increase due to the reduction of the spatial hole burning effect. For AR-HR combination, the lasing wavelength of CC DFB laser has distributed over the stopband of DFB. As CR increases, the lasing wavelength concentrates on the long wavelength side for IP CC DFB laser, while on the short wavelength side for AP CC DFB laser. As ｜$\chi$L｜ increases, the width of the wavelength distribution decreases and the lasing wavelength moves to the long wavelength side.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.21-21
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• 2000

The Josephson Plasma resonance in single crystalling Bi2Sr2CaCu2O8 has been investigated at a microwave frequency of 35 GHz in a cavity resonator. A sharp resonance is observed in a perpendicular oscillating magnetic field. The former is independent of the sample dimension, shile the latter shift to higher field as the sample size L is reduced, and it disappears when L becomes smaller than the critical length. The longitudinal plasma mode is a Nambu-Goldston mode in a superconductor, the experimental distinction between the longitudinal and the transverse mode leads to the conclusion that the existence of the Nambu-Goldston mod as predicted by Anderson was experimentally confirmed by direct observation of the Josephson plasma resonance with longitudinal excitations. The finite gap found in Josephson plasma resonance also provides a direct proof of the Anderson-Higgs mechanism within the context of the spontaneously broken phase symmetry of the Gauge-field theory in a superconductor.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.547-551
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• 1995

We analyze the nonlinearity of chiral media and coupled-mode theory of chiral multilayers. In first topic, second order nonlinear coupled equations are constructed and a phase matchine method is suggested. This approach can be developed to higher order nonlinearity and electric-field-induced second harmonic generation. In second topic, coupled mode equation in chiral multilayers is constructed, and solved for both codirectional coupling and contradirectional coupling. There is a previous formulation about chiral mutilayers[1] with 4$\times$4 matrix but it did not give detail results, so this approach will be compared with that.

• Korean Journal of Hydrosciences
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• v.1
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• pp.99-106
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• 1990

An extensive biological nutrient removal pilot plant study of anoxic/anaerobic/ aerobic treatment process was conducted to eastblish an optimum operational mode using primary dffluent. Two operational modes, (1) Qr/Q was 3.0 and maintaining EMLSS of 3100 mg/L in which the best operational results were obtained from previous bench scale study using synthetic wastewater (2) Qr/Q was 0.5 and EMLSS of 2200 mg/L which was compatible with the main plant, were Compared and evaluated for removal of nitrogen and/or phosphorous under field conditions. The nitrogen removal increased with increasing recycle ratios, but the phosphorous removal revealed more consistent results with 83percent removal efficiency in the second mode compared with 80 percent in the first mode. Above all, the two modes equally showed good BOD and nitrogen removals by nitrification-denitrification processes. It was also observed that no scum formed in the pilot plant and the sludge exhibited excellent settling characteristic all the time. The modified biological nutrient removal train can be adopted to the main plant without any major changes of their operational modes.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.82-83
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• 2000

굴절율이 외부보다 큰 실린더 (cylinder)나 스피어 (sphere)는 경계면에서의 전반사에 의해 손실이 매우 적은 high-Q 공진기가 될 수 있음이 잘 알려져 있다. 크기가 수 십 $mu extrm{m}$ 되는 실린더나 스피어에서의 공명모드는 편광(TM, TE), 모드 수 (mode number) n, 모드 순서 (mode order) l에 의해 정의되고 WGM (whispering gallery mode)라고도 불리워진다$^{(1)}$ . 모드 수n 이 클수록 모드 순서 l이 작을수록 공명모드의 Q 값은 큰 경향을 가진다. 액체 방울이나 액체 제트와 같이 열적 섭동에 민감한 마이크로 공진기 (micro-cavity)의 경우 Q값이 $10^{7}$ 정도로 제약되나, 실리카 마이크로 스피어 (micro-sphere)와 같은 고체 구에서 측정된 Q값은 약 $101^{10}$ 정도로 손실이 매우 적은 공진기가 될 수 있다$^{(2)}$ . 이와 같은 마이크로 공진기 특성을 이용하여 다양한 형태의 마이크로 공진기 레이저 대한 연구가 진행되어 왔다. 색소가 첨가된 고체구, 액체 방울, 액체 제트 등에서 기본적인 실험이 이루어졌고 반도체마이크로 스피어 구조에서 WGM 레이저$^{(3)}$ , polymer disc laser$^{(4)}$ , 광양자테 (photonic quantum ring)$^{(5)}$ 특성 연구 등이 실용가능성을 목표로 진행되고 있다. (중략)

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1997.11a
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• pp.140-145
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• 1997

A stuey to investigate the perception characteristics of color and brightness was conducted in a combined PC and TV monitor, The objective of this study is to suggest user's favorite color temperature in PC mode and user's favorite contrast in TV mode. Investigated factors were monitor coating(coatiog vs. non-coation)and screen brightness (30fL vs. 35fL)in first experiment and monitor coating and pucture movement(static vs. dynamic) in second experiment. The first experiment was conducted in TV mode. Twenty-three subjects (male 12, female 11) perticipated in this experiment. In first experiment, average color temperatures were about 8000K in all experimental conditions. In addition, there was significant difference between coating and non-coating screen at 0.1 level. In second experiment, average contrasts were obtained in all esperimental conditions. There was significant difference between coating and ndn-coating screen at 0.05 level, In addition, there was significant difference between static picture and dynamic picture at 0.1 level