• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4A
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• pp.307-314
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• 2010

In this paper, a receive diversity combining technique is proposed for single-carrier frequency division multiple access (SC-FDMA)-based cooperative relay systems when discrete Fourier transform (DFT) spreading sizes for mobile station (MS) and relay station (RS) are different. The proposed technique is composed of a DFT spreading size adjustment block, a phase rotation compensation block, a channel phase compensation block, and a receive diversity combining block. The proposed technique is robust to multipath channels and can be operated with a relatively small computational complexity because receive diversity combining is performed with scalar operations in the frequency-domain. It is shown by computer simulation that the proposed receive diversity combining techniques achieve a performance gain over the conventional maximal ratio combining (MRC) techniques for SC-FDMA-based cooperative relay systems.

• Journal of IKEEE
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• v.28 no.3
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• pp.303-309
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• 2024

This paper proposes a high-gain phased array antenna that can provide private network communication services for large office spaces, factories, and other large-scale facilities, specifically designed for millimeter-wave band 5G (5th generation) networks. The proposed antenna features a 4×4 array structure with eight sub-arrays, each consisting of a 1×2 series array. To achieve high side-lobe characteristics, an offset array structure is applied by shifting even-numbered rows by one unit, combined with power tapering to adjust the size of individual radiating elements. This design achieves a high side-lobe level (SLL) of 22.3 dB and a high gain of 18.1 dBi. Additionally, the antenna provides gain characteristics of at least 15.2 dBi and 17.4 dBi within the intended beam steering range of ±45° in the azimuth direction and ±10° in the elevation direction, ensuring smooth communication services over a wide service area.

• Geophysics and Geophysical Exploration
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• v.24 no.4
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• pp.180-193
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• 2021

The complex resistivity method is an exploration technique that can obtain various characteristic information of underground media by measuring resistivity and phase in the frequency domain, and its utilization has recently increased. In this paper, a three-dimensional inversion algorithm for the CR data was developed to increase the utilization of this method. The Poisson equation, which can be applied when the electromagnetic coupling effect is ignored, was applied to the modeling, and the inversion algorithm was developed by modifying the existing algorithm by adopting comlex variables. In order to increase the stability of the inversion, a technique was introduced to automatically adjust the Lagrangian multiplier according to the ratio of the error vector and the model update vector. Furthermore, to compensate for the loss of data due to noisy phase data, a two-step inversion method that conducts inversion iterations using only resistivity data in the beginning and both of resistivity and phase data in the second half was developed. As a result of the experiment for the synthetic data, stable inversion results were obtained, and the validity to real data was also confirmed by applying the developed 3D inversion algorithm to the analysis of field data acquired near a hydrothermal mine.

• The Korean Journal of Archival Studies
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• no.30
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• pp.125-174
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• 2011

Railway Station in Korea built for purpose to plunder resource and invade China 19 and 20 century early, It functioned as main transportation and important role in local history. However, Since the late 1990s, Railway Station in Korea is facing major changes due to Railroad Improvement and Restructuring plan. Photography is useful way to represent memory and local history about railway station, but Photography Documentation on railroad station were not discussed until now due to indifference of the KORAIL and peculiarities of national security facilities for a long time. This study suggest what is document activities and facilities of railway station, use value analysis about railway station's value firstly. next, this study set each documentation area with value analysis for a basis and present concrete example. finally, this study adapt documentation area and detail to classification scheme and apply activities and facilities of supplement or revision to classification scheme.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.8
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• pp.44-47
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• 2008

In this paper, a new circuit is proposed to minimize the charging and discharging current mismatch in charge pump for UWB PLL application. By adding a common-gate and a common-source amplifier and building the feedback voltage regulator, the high driving charge pump currents are accomplished. The proposed circuit has a wide operation voltage range, which ensures its good performance under the low power supply. The circuit has been implemented in an IBM 0.13um CMOS technology with 1.2V power supply. To evaluate the design effectiveness, some comparisons have been conducted against other circuits in the literature.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.693-696
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• 2011

본 논문에서는 레벨셋 방법을 이용하여, 소음을 차단하기 위한 음향 구조물의 형상 최적 설계를 수행하였다. 음향 결정 구조에서는 음향이 흩어져 있는 결정 구조에 의해서 굴절되기 때문에 결정 모양을 조정함으로써, 음향 거동을 제어 할 수 있다. 형상 최적 설계의 목적은 특정한 각도와 각속도로 입사되는 입사파에 대해서 음향 투과율(acoustic transmittance)이 최소가 되도록 음향 결정의 형상(inclusion shape)을 결정하는 것이다. 음향 압력(acoustic pressure)은 주기성을 갖는 음향 결정에 대해서 헬몰츠(Helmoltz)형태의 지배 방정식을 풀어서 얻을 수 있다. 본 연구에서는 음향 구조물로 결정이 수평 방향으로는 주기적으로 무한히 분포하고 수직방향으로는 유한한 층간 구조를 가지고 있는 소음 방어벽 (Noise barrier)을 고려한다. 결정의 위치는 고정되어 있고, 결정의 형상을 설계 변수로서 음파의 거동을 제어할 수 있도록 하였다. 주기적 구조물을 고려하기 때문에 결정의 좌와 우에 Bloch 이론을 적용해 주기적 경계조건을 부과하였고, 소음 방어벽 위와 아래에는 임피던스 행렬(impedance matrix)를 이용하여, 무한 균질 영역과 소음 방어벽사이의 음파 투과를 모사하였다. 복잡한 형상 변화를 표현하기 위해 임시적 경계를 이용한 레벨셋 방법을 사용하였다. 설계 민감도 해석을 통해 목적함수가 감소하는 방향으로 경계에서의 수직 벡터를 계산하고, 이를 헤밀턴-자코비(Hamilton-Jacob) 방정식에 대입하여, 최적의 형상을 나타내는 레벨셋 함수를 구하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.5
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• pp.567-577
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• 1998

When continuous and discontinuous microstrip is analyzed with FDTD(Finite Difference Time Domain) method, we used Berenger's 3D-PML as absorbing boundary condition, and IST(Inner Source Technique) was used for source excitation instead of front excitation that is existing method. In the case using IST, we have observed that analyzed characteristic is not affected by the reduced computational domain of the side and top face in which evanescent field and radiation field is exist. Also, if we control the position of the inner source, we could effectively reject the influence of the reflective wave by mean of imperfective boundary condition. In this paper, by using IST, we have calculated dispersive characteristic and characteristic impedance of the microstrip. And we have calculated magnitude and phase of the scattering coefficient, and obtained equivalent circuit of the open microstrip end.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.3
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• pp.34-41
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• 2011

This paper presents a wide tuning range, fine-resolution DCO (Digitally Controlled Oscillator) with an active inductor. In order to control the frequency of the DCO, the transconductance of the active inductor is tuned digitally. In addition, the DCO gain needs to be calibrated digitally to compensate for gain variations. To cover the wide tuning range, an automatic three-step coarse tuning scheme is proposed. The DCO total frequency tuning range is 1.4 GHz (2.1 GHz to 3.5 GHz), it is 58 % at 2.4 GHz. An effective frequency resolution is 0.14 kHz/LSB. The proposed DCO is implemented in 0.13 ${\mu}m$ CMOS process. The total power consumption is 6.6 mW from a 1.2 V supply voltage. The phase noise of the DCO output at 2.4 GHz is -120.67 dBc/Hz at 1 MHz offset.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.5
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• pp.522-527
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• 2011

In this work, a 54 GHz divide-by-3 injection-locked frequency divider(ILFD) based on ring oscillator has been developed in a 0.13-${\mu}M$ Si RFCMOS technology for phase-locked loop(PLL) application. The free-running frequency is 18.92~19.31 GHz with tuning range of 0~1.8 V, consuming 70 mW with a 1.8 V supply voltage. At 0 dBm input power, the locking range is 1.02 GHz(54.82~55.84 GHz) and, with varactor tuning of 0~1.8 V, the total operating range is 2.4 GHz(54.82~57.17 GHz). The fabricated circuit size is 0.42 mm${\times}$0.6 mm including probing pads and 0.099 mm${\times}$0.056 mm for core area.

• Journal of Korean Society of Disaster and Security
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• v.5 no.2
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• pp.35-42
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• 2012

Despite the importance of disaster management officers of disaster management agencies at the local government to protect the lives of civilians and their properties, there is a lack of research or literature in their roles and responsibilities. In fact, there is a urgent need to set clear roles and responsibilities for them. This study scrutinizes how to disaster managers should behave in specific setting that differentiates from other administrative managers based on domestic and foreign literature review. Although, the role of disaster manager seem to be similar to administrative manager, there are some differences particularly in the areas that disaster manager has to work as an expert in saving lives and properties that has to be further emphasized. When working on disaster management process of prevention and resoration, the key task are based on mid and low level officers. On the other hand, preparedness and response process that involve rapid decision making and cooperation with other department, persuasion of local residents and resource pooling are carried out by mid and high level managers because it requires control capacity and decision making skills.