• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.215-218
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• 2006

In this paper, a small size, $7{\times}6mm^2$, Low Noise Amplifier(LNA) using LTCC process was fabricated with multi-layer structure for 2.4GHz wireless LAN. The measured results demonstrate that the bandwidth is 130 MHz, and the operating frequency is from 2.39GHz to 2.52GHz. The power gain is above 7.3 dB in the operating frequency range and the gain flatness is 0.5 dB. The maximum S11 is -4 dB and the maximum S22 is -7.5 dB. The noise figure is less than 1.83 dB. The measured power gain, S11 and S22 were had poorer performance than the simulation results. The reason for this discrepancy is that the input and output matching was not performed exactly. However, the noise figure of the LTCC low noise amplifier is better than simulation result. It is found that it is possible to fabricate a LTCC low noise amplifier in a small size.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.311-315
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• 2000

A numerical investigation is made of time-dependent buoyant convection in a square of a non-Boussinesq fluid. The density-temperature$({\rho}-T)$ relation is modeled by a quadratic function, with the maximum density ${\rho}_M$ at temperature $T_M$. The horizontal walls of the square are insulated, and a pulsating temperature $T_H=T_M+{\Delta}T'\;sin({\omega}{\tau})$ is imposed on the hot vertical sidewall. The temperature at the cold wall $T_c$ is constant. Extensive numerical solutions to the governing Navier-Stokes equations are portrayed. Resonance is identified by monitoring the amplitude of the mid-plane Nusselt number, $A(Nu^*)$. The primary resonance frequency is found by matching ${\omega}$ to the nondimensional basic mode $N_1$ of internal gravity oscillations. Due to the quadratic$({\rho}-T)$ relationship, the effective pulsation frequency for density, $2{\omega}$, is meaningful, which brings forth the secondary resonance frequency, i.e., $2{\omega}=N_1$

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.1
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• pp.33-38
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• 2000

In this study, multilayer piezoelectric actuators were fabricated with 75 layers by a conventional multi-layer capacitor (MLC) techniques, using 70Ag/30Pd paste as an internal electrode which can be sintered at low temperature and have cost down effect in mass productions. The multilayer piezoelectric actua-tors had no defects such as diffusions of internal electrode to ceramic bodies and shortages of internal electrodes. The multilayer piezoelectric actuators did not show the crack in the ceramics parts and the gapping phenomena in the external eletrodes when Ag paste was used as external electrodes. The multilayer piezoelectric actuators showed a maximum displacement of 4${\mu}{\textrm}{m}$ at 100V dc voltage and kept the maximum displacement constant for 300 seconds. The multilayer piezoelectric actuators showed good matching properties between ceramic bodies and AgPd internal electrodes. We confirmed the possibility of large-scaled production of the multilayer piezoelectric actuators with superior electrical properties and cost down effect using 70Ag/30Pd paste as an internal electrodes.

• The Academic Congress of Korean Shoulder and Elbow Society
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• 2009.03a
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• pp.175-175
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• 2009

Despite its importance for the understanding of joint kinematics in vivo, there has been few studies about shoulder joints. The purpose of this study is to analyze the glenohumeral joint during internal and external rotation at 90 degrees of abduction using in vivo noninvasive motion analysis system. MRI was performed for the following seven positions from maximum internal rotation to maximum external rotation at intervals of 30 degrees. We used 3D-gradient echo sequencing (TR: 12 ms, TE: 5.8 ms, 0.8 mm-slice thickness). Our method is based on matching three-dimensional MR images by the similarity of the image intensity. We analyzed the in vivo three-dimensional motions of the glenohumeral and scapulothoracic joint during this motion. In scapla plane, the mean rotation angle of the glenohumeral join was 105.5 degrees ($SD{\pm}39.0^{\circ}$). The mean rotation angle of the scapulothracic joint was 27.5 degrees ($SD\;{\pm}\;7.7^{\circ}$). The contribution ratio is almost 3.8:1 of glenohumeral and scapulothracic joint respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.4
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• pp.121-129
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• 2001

The semi-adiabatic temperature rise and the losses of temperature of cement paste, mortar and concrete were measured by an apparatus of semi-adiabatic temperature. Heat of hydration was measured by a conduction calorimeter and adiabatic temperature rise of concrete was measured by an adiabatic calorimeter. The derived equation which can assume the adiabatic temperature was proposed by measuring the semi-adiabatic temperature of concrete. The maximum adiabatic temperature rise of concrete obtained by the derived equation of adiabatic temperature, $T_{ad}(t)=T_{sad}(t)+T_{dis}(t)$, showed $55^{\circ}C$ approximately and it had good relation with the other one obtained by the heat of hydration of cement paste and with maximum value which was measured by the adiabatic calorimeter. The adiabatic temperature rise obtained by derived equation was a different information in comparison with the value obtained by adiabatic temperature rise equations by Hell and et. al. in early age, but it showed similar tendencies with the other one according to elapsed time. Adiabatic temperature rise of lich mix concrete with highly cement content was predicted. The adiabatic temperature rise of cement paste and mortar obtained by derived equation from us showed comparatively matching results to compared with that of obtained by adiabatic temperature equation from concrete standard specification.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1599-1600
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• 2006

In this paper, a small size, $7{\times}6\;mm^2$, Low Noise Amplifier(LNA) using LTCC process was fabricated with multi-layer structure for 2.4GHz wireless LAN. The measured results demonstrate that the bandwidth is 130 MHz, and the operating frequency is from 2.39GHz to 2.52GHz. The power gain is above 7.3 dB in the operating frequency range and the gain flatness is 0.5 dB. The maximum S11 is -4 dB and the maximum S22 is -7.5 dB. The noise figure is less than 1.83 dB. The measured power gain, S11 and S22 were had poorer performance than the simulation results. The reason for this discrepancy is that the input and output matching was not performed exactly. However, the noise figure of the LTCC low noise amplifier is better than simulation result. It is found that it is possible to fabricate a LTCC low noise amplifier in a small size.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10b
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• pp.304-306
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• 2004

생물정보학에서 서열의 유사성을 예측하는 것은 가장 중요한 문제 중의 하나이다. 염기 서열의 유사성을 검색하는 유용한 검색도구들에는 BLAST와 FASTA 등이 있으며 이러한 도구들은 새로운 유기체에 대한 실제 염기 서열을 필요로 한다. 이 경우 서열을 얻기 위한 sequencing 작업이 필요로 하며 시간적인 면에 있어서 상당한 비용을 요구한다. 본 논문에서는 sequencing 작업을 하지 않고 간단한 실험에서 얻을 수 있는 부분적인 Sequence 정보만을 대상으로 데이터 베이스에서 검색을 할 수 있는 두 개의 RIFLE(Rapid Identification of Microorganisms by Fragment Length Evaluation), MSMP(Maximum Site Matching Problem) 알고리즘을 구현하고 실험을 통해 두 알고리즘을 비교 평가한다. 실험결과 RIFLE 알고리즘이 수행 속도 면에서 빠른 반면 MSMP가 산출한 결과에 비해서 신뢰성이 떨어짐을 확인하였다.

• Journal of electromagnetic engineering and science
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• v.17 no.3
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• pp.147-152
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• 2017

This paper presents a frequency doubler operating at G-band that exceeds the maximum oscillation frequency ($f_{max}$) of the given transistor technology. A common-source transistor is biased on class-B to obtain sufficient output power at the second harmonic frequency. The input and output impedances are matched to achieve high output power and high return loss. The frequency doubler is fabricated in a commercial 150-nm GaAs pHEMT process and obtains a measured conversion gain of -5.5 dB and a saturated output power of -7.5 dBm at 184 GHz.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.204-207
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• 2003

PV model is presented based on the shockley diode equation. The simple model has a photo-current source, an single diode junction and a series resistance and includes temperature dependences. An accurate PV module electrical model is presented, matching with boost converter MPPT strategy and demonstrated in Matlab for a typical general purpose solar cell. Given solar insolation and temperature, the model returns current vector and MPP.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.177-180
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• 2002

Generally, it is very difficult to inspect geometric shape of large 2D objects after machining. To maintain the accuracy for inspection, a robot vision is used to divide overall shape into several enlarged images, and image processing technique is applied to acquire one minute geometric contour. The inspection is to compare the NC data with the measured contour data by the vision system, and the algorithm is to rotate to minimize the maximum deviation coinciding two geometric centers. This paper experimentally shows that the proposed inspection algorithm is very useful fur a large machined object.