• ETRI Journal
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• 제45권1호
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• pp.163-170
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• 2023

We report an electroabsorption modulator (EAM)-integrated distributed Bragg reflector laser diode (DBR-LD) capable of supporting a high data rate and a wide wavelength tuning. The DBR-LD contains two tuning elements, plasma and heater tunings, both of which are implemented in the DBR section, which have blue-shift and red-shift in the Bragg wavelength through a current injection, respectively. The light created from the DBR-LD is intensity-modulated through the EAM voltage, which is integrated monolithically with the DBRLD using a butt-joint coupling method. The fabricated chip shows a threshold current of approximately 8 mA, tuning range of greater than 30 nm, and static extinction ratio of higher than 20 dB while maintaining a side mode suppression ratio of greater than 40 dB under a window of 1550 nm. To evaluate its modulation properties, the chip was bonded onto a mount including a radiofrequency line and a load resistor showing clear eye openings at data rates of 25 Gb/s nonreturn-to-zero and 50 Gb/s pulse amplitude modulation 4-level, respectively.

• ETRI Journal
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• 제46권2호
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• pp.333-346
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• 2024

Various techniques for noninvasively focus microwave energy on lesions have been proposed for thermotherapy. To focus the microwave energy on the lesion, a focusing parameter, which is referred to as the magnitude and phase of microwaves radiated from an external array antenna, is very important. Although the finite-difference time-domain (FDTD)-based time-reversal (TR) focusing algorithm is widely used, it has a long processing time if the focusing target position changes or if optimization is needed. We propose a technique to obtain multistatic data (MSD) based on Green's function and use it to derive the focusing parameters. Computer simulations were used to evaluate the electric fields inside the object using the FDTD method and Green's function as well as to compare the focusing parameters using FDTD- and MSD-based TR focusing algorithms. Regardless of the use of Green's function, the processing time of MSD-based TR focusing algorithms reduces to approximately 1/2 or 1/590 compared with the FDTD-based algorithm. In addition, we optimize the focusing parameters to eliminate hotspots, which are unnecessary focusing positions, by adding phase-reversed electric fields and confirm hotspot suppression through simulations.

• ETRI Journal
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• 제31권6호
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• pp.765-769
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• 2009

In this paper, we present the fabrication of 40 Gb/s traveling-wave electroabsorption modulator-integrated laser (TW-EML) modules. A selective area growth method is first employed in 40 Gb/s EML fabrication to simultaneously provide active layers for lasers and modulators. The 3 dB bandwidth of a TW-EML module is measured to be 34 GHz, which is wider than that of a lumped EML module. The 40 Gb/s non-return-to-zero eye diagram shows clear openings with an average output power of +0.5 dBm.

• Architectural research
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• 제14권4호
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• pp.117-124
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• 2012

High rise office buildings represent one of the most energy-intensive architectural typologies. The growth of urban population necessitates sustainable high rise towers that lessen environmental impacts and energy consumption. Among various sustainable strategies, the integrated design is long known to be an important process that has great impact on building's sustainability. The framework for this paper is based on the case study of integrated towers that are located in different climate zones. The paper specifically addresses to what extent climate conditions influence the design of a high rise building and what kinds of the climate integrated design has been implemented. Qualitative case studies were carried out using published data and architectural drawing set. The technical work presented in the paper is based on computer simulation that examines the insolation analysis using hourly recorded weather data. The analysis results revealed that the site and building envelope integration and the site and building service systems have shown the most frequently employed in the integrated towers through the implementation of renewable resource integration, high performance envelopes and sustainable building service systems. Internal comfort and further energy saving in the integrated towers are offered through an automatic building management system. Due to the dynamic climate conditions, integration of building systems requires a sophisticated approach to building sustainability.

• Steel and Composite Structures
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• 제32권2호
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• pp.225-237
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• 2019

In this research, the dynamic stability and nonlinear vibration behavior of a smart rotating sandwich cylindrical shell is studied. The core of the structure is a functionally graded material (FGM) which is integrated by functionally graded piezoelectric material (FGPM) layers subjected to electric field. The piezoelectric layers at the inner and outer surfaces used as actuator and sensor, respectively. By applying the energy method and Hamilton's principle, the governing equations of sandwich cylindrical shell derived based on first-order shear deformation theory (FSDT). The Galerkin method is used to discriminate the motion equations and the equations are converted to the form of the ordinary differential equations in terms of time. The perturbation method is employed to find the relation between nonlinear frequency and the amplitude of vibration. The main objective of this research is to determine the nonlinear frequencies and nonlinear vibration control by using sensor and actuator layers. The effects of geometrical parameters, power law index of core, sensor and actuator layers, angular velocity and scale transformation parameter on nonlinear frequency-amplitude response diagram and dynamic stability of sandwich cylindrical shell are investigated. The results of this research can be used to design and vibration control of rotating systems in various industries such as aircraft, biomechanics and automobile manufacturing.

• ETRI Journal
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• 제27권5호
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• pp.484-490
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• 2005

We fabricated 40 Gb/s front-end optical receivers using spot-size converter integrated waveguide photodiodes (SSC-WGPDs). The fabricated SSC-WGPD chips showed a high responsivity of approximately 0.8 A/W and a 3 dB bandwidth of approximately 40 GHz. A selective wet-etching method was first adopted to realize the required width and depth of a tapered waveguide. Two types of electrical pre-amplifier chips were used in our study. One has higher gain and the other has a broader bandwidth. The 3 dB bandwidths of the higher gain and broader bandwidth modules were about 32 and 42 GHz, respectively. Clear 40 Gb/s non-return-to-zero (NRZ) eye diagrams showed good system applicability of these modules.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2018년도 추계학술대회
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• pp.119-121
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• 2018

해상교통 환경변화에 부응하고 나아가 대형 해양사고 방지와 인명사고 예방을 위해 구축, 운영 중인 항로표지통합관리시스템을 2012년 제정된 "해양교통시설 통합관리시스템 표준규격서"를 준용하여 개선을 하고자 한다. 기존에 구축되어 운영 중인 시스템의 자원을 재활용하고 운용소프트웨어를 개선하며, 자국 시스템 설치에 있어 표준화하여 운영 및 유지관리가 용이하도록 한다.

• 한국의상디자인학회지
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• 제14권4호
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• pp.99-111
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• 2012

This study intends to explore the collaborative expression in the modern fashion design by analyzing the collaboration of motifs symbolizing Korean cultural identity. As for the data research, in order to examine the expressional objects of collaboration in the collections of the fashion designers from Korea and overseas who have applied the Korean culture among their collections posted on the Internet sites, www.firstview.com, and www.style.com from 2005 to 2012 were collected for analysis. 923 pictures used in the analysis sheet. As for the research method, the content analysis method was used. In the modern fashion design, the collaborative expression in the motifs symbolizing Korean cultural identity are limited to tangible expression, intangible expression, integrated expression. The results of this study were as follows. First, in the tangible expression, traditional tangible assets are used in the shapes, items, colors, materials, patterns and details to symbolize uniquely Korean image. The intangible expression, the applicability for Korean intangible assets include the master's (intangible cultural assets) and the craftsmanship of the modern designers being collaborated onto the contemporary customs to express the Korean traditional culture in a realistic or an abstract trend. The hybride expression, it is to represent Korean thoughts and values using the tangible elements. Second, The expressivity of collaboration of each year mostly shows integrated expression, intangible expression and tangible expression were shown respectively. The trend of seasonal collaboration expressivity was muchly the integrated expression in most seasons, and intangible expression and tangible expression followed respectively. It is recognizable that the expressivity of collaboration of each designer was; integrated expression was muchly shown in Lie Sang Bong and Lee Young Hee's works, Duri Jung showed much of intangible expression, and much tangible expressivity was shown in Carolina Herrera.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2000년도 추계 학술발표회 논문집
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• pp.115-120
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• 2000

The analysis of flux distribution under stead-state in large power reactors with assymetry reactivity insertions requires the use of three-dimensional diffusion calculations. For the purpose, consistently formulated modern nodal methods based on higher order interface techniques have become popular tools for flux distributions in large commercial nuclear reactors. Among the earlier developments, the nodal Green's function method obtains its nodal interface equation from the transverse-integrated integral diffusion equation using a finite-medium Green's function. In this method, the outgoing current from a node surface is formulated as a response of the incoming currents and the spatially integrated neutron source within the same node. The well-known nodal expansion method is also based on an interface partial current formulation. Nodal methods high-level interface variables, i.e., interface net current and flux, may be more computationally efficient than the nodal Green's function method because they have one fewer unknown per interface. The Analytic Nodal Method(ANM), which can be classified as an interface net current technique and, was faster in solving some standard benchmark problems than the other two methods.(omitted)

• Architectural research
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• 제22권4호
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• pp.105-112
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• 2020

The purpose of this study is to establish a method for assessing a building's risk against disaster, tentatively named the Korean integrated disaster evaluation simulator (K-IDES). Based on previous studies, FEMA's risk management series and FEMA IRVS are selected as case studies for developing a frame work of K-IDES, through the comparative analysis of domestic building design guides, codes, and special acts related to disasters, in order to develop a risk assessment methodology for quantitative results. The assessment method consists of a classification system and calculating risk, and a simulation applying the developed checklist in K-IDES to similar types of high-rise buildings will be conducted to validate its accuracy. The final goal is to systemize an integrated risk management in a high-rise building against disasters for the purpose of recognizing vulnerable areas from the beginning of the design process and reinforcing it from potential threats after construction.