• The Korean Journal of Applied Statistics
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• v.14 no.1
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• pp.13-24
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• 2001

In this paper, we investigated mean estimation methods in two-phase sampling. Under the fixed expected cost we reviewed the optimal sample sizes, minimum variances and approximate unbiased variance estimators for usual ratio estimator, stratified sample mean with proportional allocation and Rao's allocation of the second phase sample. Also we proposed combined ratio estimator, which uses both ratio estimation and stratification and derived optimal sample size, minimum variance and unbiased variance estimator. Through a limited simulation study, we compared estimators by design effects and came to know that ratio estimator is more efficient than stratified sample mean in some cases and inefficient in the other cases, but combined ratio estimator is more efficient than others in most cases.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.159-160
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• 2014

기존 인터리브드 방식의 2상 이중 강압형 직류-직류 컨버터는 비절연 강압형 직류-직류 컨버터로 출력 전류 리플 감소, 이중 강압으로 인한 스위치 전압 스트레스 감소, 인덕터 전류 불평형 문제 해결, 그리고 스위칭 손실 감소 등의 장점으로 대용량 직류-직류 컨버터에 적합하다. 본 논문에서는 기존의 2상 이중 강압형 직류-직류 컨버터에 결합 인덕터를 적용하여 인덕터의 전류 리플을 감소시키고 이를 수치적으로 해석한다. 또한 결합 인덕터의 문제점인 각 상의 인덕터 전류 불평형으로 인한 인덕터 포화현상에 대하여 실험을 통해 확인 한다.

• Journal of the Korean Chemical Society
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• v.38 no.6
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• pp.405-410
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• 1994

Molecular orbital calculations suggest that an interaction between the psoralen derivatives of excite state and the thymine of ground state is dicussed in terms of their differing abilities to molecular complex. PM3-CI-UHF indicates that photocycloadducts across the C3-C4 and C4'-C5' double bonds of the methylpsoralen and hydroxypsoralen with thymine C5-C6 double bonds were deduced to be formed by their preferable frontier orbital interactions. The electronic properties of psoralen derivatives in the ground and excited states correlate with this difference in structure-activity relationship.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.138-138
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• 2010

이중 주파수를 이용한 고주파 용량성 결합 플라즈마 장치는 반도체 및 디스플레이 생산 공정에서 널리 사용되는 장치 형태이며 일반적으로 이온 플라즈마 주파수보다 높은 주파수의 고주파 전력과 이온 플라즈마 주파수보다 낮은 주파수의 저주파 전력을 인가하여 플라즈마 발생 밀도 및 입사 이온 에너지를 독립적으로 조절할 수 있다. 용량성 결합 플라즈마 장치에서는 전극의 쉬스 임피던스가 비선형적으로 변화함에 따라 전극의 전압, 전류 및 플라즈마 전위는 수많은 고조파를 포함하게 되며, 이중 주파수가 인가된 경우 이러한 고주파와 저주파 신호의 고조파가 상호 변조된 형태로 나타나게 된다. 본 연구에서는 주파수에 따른 이온의 거동 특성 차이를 이용하여 변조된 형태의 Lieberman의 비균일 RF쉬스 모델을 가정한 고주파 쉬스를 단순한 저주파 쉬스로 모사하였다. 단순화된 저주파 쉬스 임피던스를 이용한 회로 모델을 구성하여 100MHz와 2MHz RF전력을 사용하는 용량성 결합 플라즈마 장치에서 측정된 전극 전압, 전류 및 플라즈마 전위 신호의 위상차 및 고조파 발생 특성을 분석하였다.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.4
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• pp.1-7
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• 1999

The demands for the various type of directional coupler, which is for the sampling of the signal levels in mobile communication baseband or transceiver systems, are growing. The proposed dual directional coupler, which has three parallel coupled transmission lines, can provide the dual coupling and good isolation characteristics between the coupling ports. In this paper, the novel analysis method and the design equation of even and odd mode for the dual directional coupler, which is employing the asymmetrically coupled transmission lines, are proposed. Using the proposed method, the dual directional coupler for PCS system has been designed and fabricated. We obtained the desired coupling value and the high directivity of 40dB. Measured results show the validity of this design method.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.137-142
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• 1997

We synthesized the intercalation compound between a layered double hydroxide and an ethyl orange. The orientation of the intercalated ethyl orange into the layered double hydroxide was investigated. The molecular plane of the ethyl orange and its N＝N axis lie nearly perpendicular to the hydroxide layers with an antiparallel pattern.

• Restorative Dentistry and Endodontics
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• v.30 no.4
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• pp.283-293
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• 2005

The purpose of this study was to evaluate the effect of dual bonding technique by comparing microshear bond strength between two different luting methods of resin cement to tooth dentin. Three dentin bonding systems(All-Bond 2, One-Step, Clearfil SE Bond), two temporary cements (Propac, Freegenol) were used in this study. In groups used conventional luting procedure, dentin surfaces were left untreated. In groups used dual bonding technique, three dentin bonding systems were applied to each dentin surface. All specimens were covered with each temporary cement. The temporary cements were removed and each group was treated using one of three different dentin bonding system. A resin cement was applied to the glass cylinder surface and the cylinder was bonded to the dentin surface. Then, micro-shear bond strength test was performed. For the evaluation of the morphology at the resin/dentin interface, SEM examination was also performed. 1. Conventional luting procedure showed higher micro-shear bond strengths than dual boning technique. However, there were no significant differences. 2. Freegenol showed higher micro-shear bond strengths than Propac, but there were no significant differences. 3. In groups used dual bonding technique, SE Bond showed significantly higher micro-shear bond strengths in One-Step and All-Bond 2 (p<0.05), but there was no significant difference between One-Step and All-Bond 2. 4. In SEM observation, with the use of All-Bond 2 and One-Step, very long and numerous resin tags were observed. This study suggests that there were no findings that the dual bonding technique would be better than the conventional luting procedure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.5
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• pp.598-605
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• 2012

In this paper, a multi-layer dual-band bandpass filter using aperture-coupling is proposed. Two coupling paths are formed with the two apertures which exist between two dual-mode resonators. The coupling coefficients can be adjusted without changing the shape of resonators. The bandwidth of the second passband can be adjusted without affecting the bandwidth of the first passband using the size of an aperture between stubs of the dual-mode resonator. The aperture coupling mechanism is theoretically analysed. The dual-mode bandpass filter for the 2.4 GHz WLAN, 3.5 GHz WiMax was designed and fabricated. The fabricated filter shows centered 2.45 GHz and 3.5 GHz with 9 % and 8 % of the bandwidth.

• Journal of Advanced Navigation Technology
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• v.14 no.6
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• pp.909-915
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• 2010

In this paper, the unequal power divider based on CRLH (Composite Right/Left-Handed) transmission line with dual-band characteristic is proposed. They consist of dual-band branch line hybrid coupler, the connection between input and isolation port of hybrid coupler and ${\lambda}/4$ impedance transformer. When the transmission line between input and isolation port of hybrid coupler is asymmetrical connected, the divider is obtained the output results of the equal phase and unequal power dividing ratio. The simulation results of the divider represent the power ratio of 0 dB ~ 20 dB. To validate a function of divider, the hybrid coupler and transformer with 880 MHz and 1850 MHz is implemented. As a result, the proposed unequal divider obtains the power ratio of 3.2 dB ~ 8.8 dB at 880 MHz and 2.5 dB ~ 14.0 dB at 1850 MHz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.11
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• pp.2500-2504
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• 2011

Living organisms are composed of cells that can replicate themselves through growth, division packed with tons capacity. On DNA mutations, ie mutations in the offspring's survival and reproduction can be held against you, and packed with tons ambivalence that could benefit. In this study, the DNA double helix is used as a template for replication, we first separated into single strands of the double helix must be opened Combining the double helix portion of the location of errors in the bond provides a way to find and repair.