• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2011년도 한국우주과학회보 제20권1호
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• pp.31.4-32
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• 2011

The previous KRISS profilometer design used an aluminum profile structure to which a bar-type reference mirror subsystem and the measurement subsystem are mounted. The earlier design suffers from low stiffness as shown from the first resonance mode of 45.1 Hz. The improved mechanical design we describe in this study replaces the aluminium profile structure with a granite structure of $1340{\times}220{\times}230$ in dimension. The finite element analysis results for the revised design show 0.001 degree in probe contact angle variation. The first resonance mode was computed to 91.2 Hz that is much better than 45.1 Hz from the previous design. We describe the improved design, structural analysis results and how these results would satisfy the form accuracy requirement of 1 ${\mu}m$ PV.

• 한국전자파학회논문지
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• 제25권12호
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• pp.1300-1305
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• 2014

근접장 마이크로파 현미경의 핵심 부품인 H-형태 소형 개구를 가진 도파관 탐침에 대해 등가회로를 표현하고 해석하였다. 파장에 비해 작은 사각형 또는 원형의 소형 개구는 유도성 성분인데, 여기에 리지 구조를 부착하는 것은 용량성 성분을 연결하여 이로 인해 투과 공진을 일으키는 것으로 볼 수 있다. 이러한 해석을 입증하기 위해 리지가 있는 소형 개구에서 용량 성분에 해당되는 리지 부분을 분리하여 대략 반파장 떨어진 지점에 세워 두고 구한 등가회로적 표현에 의한 계산 결과와 전자파 해석에 의한 계산 결과와 비교하여 거의 일치된 모습을 확인하였다. 또한, 도파관 탐침을 제작하여 반사손실을 측정하고, 계산 결과의 정확성을 확인하여 이론의 타당성을 검증하였다.

• 한국소음진동공학회논문집
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• 제18권4호
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• pp.424-431
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• 2008

Recently, it is required that acoustic transducers for underwater detection and communication sensor have wide bandwidth and low operating frequency. In this research, the new acoustic transducer is proposed. This transducer is tonpilz type, and made of 1-3 piezoelectric composites as a driving parts. The developed transducer is evaluated the TVR(transmission voltage response) and RVS(receiving voltage sensitivity) characteristics around $4{\sim}14\;kHz$ frequency range and is compared to conventional tonpilz transducer made of solid piezoelectric ceramics as a driving parts. The resonance frequency of the developed transducer is decreased by 30% and the -3 dB bandwidth is increased by 90%, compared to conventional transducer with same dimensions. The value of TVR is decreased by 9 dB and The value of RVS is the same at resonance frequency.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1994년도 추계학술대회논문집; 한국종합전시장, 18 Nov. 1994
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• pp.35-39
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• 1994

One of the important characteristics of the response of nonlinear systems is the existence of subharmonic resonances. When some conditions in parameter space are satisfied. It is possible even in the presence of damping for a periodically excited nonlinear system to possess a response which is the combination of a contribution at the excitation frequency and a component at the system natural frequency. The system natural frequency being a submultiple of the excitation frequency implies that the resulting response is a subharmonic oscillation. In general, there also co-exists, for the system, a response at the excitation frequency, and initial conditions determine which of the steady-state responses is achieved in an experiment or a numerical simulation. In single-degree-of-freedom systems with harmonic excitation, depending on the type of the nonlinearity, e.g., cubic or quadratic the frequency of subharmonic response is respectively, one-third or one-half of that of the excitation frequency. Although subharmonic resonance is one of the principal characteristics of a nonlinear system the subharmonic responses of structures in the presence of internal resonances have been studied very rarely. In this work, we consider subharmonic responses in the two-mode approximation of the plate equations. It is assumed that the two modes are in one-to-one internal resonance. Constant and periodic steady-state solutions of the averaged equations are studied. Finally, the results of direct time integration of the original equations of motion are presented and compared with those obtained from the averaged equations.

• 한국자기공명학회논문지
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• 제6권1호
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• pp.69-77
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• 2002

During the screening of material which has the antimicrobial activity against aminoglycoside-resistant bacteria, A new material $\varepsilon$-(L-$\beta$-Iysine) polypeptide from a culture medium of Streptomyces sp.(DWGS2) was isolated, and the structure and the physicochemical properties of the new material were elucidated. The new material was separated by column chromatography of the culture medium using Dowex1$\times$2, Silica gel, and Sephadex LH20 etc. The chemical structure and molecular weight were determined with the data of various NMR experiments, MALDI mass, and ESI mass experiments. The antimicrobial activity of $\varepsilon$-(L-$\beta$-Iysine) polypeptide is not only better than equal to the activity of known aminoglycoside type of antibiotics(MIC=3.125 - 6.25ug/mL) but also effective against aminoglycoside-resistant bacteria and fungi. If the mechanism of antimicrobial activity against aminoglycoside- resistant bacteria is figured out, the $\varepsilon$-(L-$\beta$-Iysine) polypeptide can be utilized for the treatment of diseases caused by aminoglycoside-resistant bacteria.

• 한국자기공명학회논문지
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• 제6권1호
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• pp.78-83
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• 2002

A new fluoroquinolone (DW-116) with a broad antibacterial spectrum was synthesized by introducing functional fluoropyridyl and methylpyrazine groups on N1, C7 position of quinolone moiety, respectively. $^{1}$H and $^{13}$ C NMR signal assignments and structure were completely elucidated by 2D-NMR methods. Physicochemical properties of products were also investigated. DW-116 is decomposed at 306.9$^{\circ}C$ and the decomposition starts at around 285$^{\circ}C$. The free base form is melt at 280.7$^{\circ}C$ and started to be decomposed immediately. DW-116 has two kinds of polymorphism which is important in drug action but these two plate and rod types have the same solubility in water. However the solubility is quite different in less or polar solvent. The plate type is more soluble in less polar solvent except in dichloromethane.

• 조명전기설비학회논문지
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• 제21권8호
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• pp.20-26
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• 2007

본 논문은 반도체 소자의 사용없이 구성된 LC 공진 타입의 점화기를 분석하고 설계하였다. 일반적으로 사용되고 있는 점화기는 다이악, 아크갭, SCR과 같은 반도체 소자가 사용된다. 이러한 반도체 소자의 사용으로 인해 회로의 구성이 복잡해지며 신뢰성이 저하된다. 따라서 본 논문에서는 수동 소자로만 구성된 점화기 회로를 분석 및 설계하였으며 제안한 점화기는 램프의 정상 상태에서는 영향을 미치지 않는다. 수학적 분석, 컴퓨터 시뮬레이션과 1[kW] 메탈 핼라이드 램프용 전자식 안정기를 제작하여 실제 적용해 봄으로서 제안한 점화기의 유용함을 증명하였다.

• 한국항해항만학회지
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• 제32권9호
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• pp.723-727
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• 2008

Sensing performances of evanescent field absorption (EFA) hetero-core fiber sensor has been presented based on EFA by changing the length and the core diameter of the single mode fiber. Experimental results have demonstrated a good feature in their relationship between the length and the core diameter of the single mode fiber. The sensor consists of 2 fiber optics which have the same cladding diameter of $125{\mu}m$ However one fiber optic used is single mode and has varying core diameter ranging from 3.3 to $5.6{\mu}m$. The other fiber is multimode type and has a thicker fixed core diameter of $62.5{\mu}m$. The 2 fiber optics are thermally spliced together. Experiments conducted to measure the resonance wavelength were carried out over a range of refractive index, to find the optimum sensing length Experiments show that core diameter of the single mode fiber and sensing length offects the linearity and sensitivity.

• Journal of Power Electronics
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• 제15권6호
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• pp.1654-1663
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• 2015

Compared to LC resonance, LCL resonance has distinct advantages such as a large resonant capability, low voltage and current stresses of the power device, constant voltage or current output characteristics, and fault-tolerance capability. Thus, LCL resonant compensation is employed for a movable Inductive Contactless Power Transfer (ICPT) system with a multi-load in this paper, which achieves constant current output characteristics. Peculiarly, the primary side adopts a much larger compensation inductor than the primary leakage inductor to lower the reactive power, reduce the input current ripple, generate a large current in the primary side, and realize soft-switching. Furthermore, this paper proposes an approximate resonant point for large inductor-ratio LCL resonant compensation through fundamental wave analysis. In addition, the PWM control strategy is used for this system to achieve constant current output characteristics. Finally, an experimental platform is built, whose secondary E-Type coils can ride and move on a primary rail. Simulations and experiments are conducted to verify the effectiveness and accuracy of both the theory and the design method.

• 한국통신학회논문지
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• 제21권12호
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• pp.3215-3226
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• 1996

In this paper a K-band harmonic oscillator competitive to ordinary Push-Push type oscillators is introduced. This oscillator is composed of two-X-band dielectric resonance circuits. To favor its harmonic generation, the load effect and the bias effect are studied to allow the maximum harmonic distortion. As results, the dielectric resonated load and the class A bias are used for the 2nd harmonic generation. analytical study for modelling of voltage controlled dielectric resonator is carried out with theoretical background. The performance of the circuit is evaluated by simulation using harmonic balanced method. The novel structure has ont only a voltage tuning circuit but also an output port at fundamental frequency as the function of prescaler for phase lockede loop application on the just single oscillation structure. In experimentation, the output freqneyc of the 2nd harmonic signal is 20.5GHz and the maximum power level of output is +5.5dBm without additional post amplifiers. the harmonic oscillator exhibits -30dBc of high fundamental frequency rejection without added extra filters. The phase noise of -90dBc/Hz at 100kHz off-carrier has been achieved under free running condition, that satisfies phase noise requirement of IESS 308. The proposed oscillator may be utilized as the clean and stable fixed local oscillator in Transmit Block Upconvertor(TBU) or Low oise Block downconvertor(LNB) for K/Ka-band digital communications and satellite broadcastings.