• Advances in aircraft and spacecraft science
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• 제2권2호
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• pp.217-232
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• 2015

To prevent over-testing of the test-item during random vibration testing Scharton proposed and discussed the force limited random vibration testing (FLVT) in a number of publications. Besides the random vibration specification, the total mass and the turn-over frequency of the load (test item), $C^2$ is a very important parameter for FLVT. A number of computational methods to estimate $C^2$ are described in the literature, i.e., the simple and the complex two degrees of freedom system, STDFS and CTDFS, respectively. The motivation of this work is to evaluate the method for the computation of a realistic value of $C^2$ to perform a representative random vibration test based on force limitation, when the adjacent structure (source) description is more or less unknown. Marchand discussed the formal description of getting $C^2$, using the maximum PSD of the acceleration and maximum PSD of the force, both at the interface between load and source. Stevens presented the coupled systems modal approach (CSMA), where simplified asparagus patch models (parallel-oscillator representation) of load and source are connected, consisting of modal effective masses and the spring stiffness's associated with the natural frequencies. When the random acceleration vibration specification is given the CSMA method is suitable to compute the value of the parameter $C^2$. When no mathematical model of the source can be made available, estimations of the value $C^2$ can be find in literature. In this paper a probabilistic mathematical representation of the unknown source is proposed, such that the asparagus patch model of the source can be approximated. The chosen probabilistic design parameters have a uniform distribution. The computation of the value $C^2$ can be done in conjunction with the CSMA method, knowing the apparent mass of the load and the random acceleration specification at the interface between load and source, respectively. Data of two cases available from literature have been analyzed and discussed to get more knowledge about the applicability of the probabilistic method.

• Earthquakes and Structures
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• 제18권5호
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• pp.567-580
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• 2020

In this paper, irregularly designed planar reinforced concrete wall structures are investigated computationally. For this purpose, structures consisting of four regular and irregular models of short-order (two-class) and intermediate (five-class) types have been investigated. The probabilistic evaluation of seismic damage of these structures has been performed by using the incremental inelastic dynamic analysis to produce the seismic fragility curve at different levels of damage. The fragility curves are based on two classes of maximum damage indices and the Jeong-Nansha three-dimensional damage index. It was found that there is a significant increase in damage probability in irregular structures compared to regular ones. The rate of increase was higher in moderate and extensive damage levels. Also, the amount of damage calculated using the two damage indices shows that the Jeong-Nensha three-dimensional damage index in these types of structures provides superior results.

• Membrane and Water Treatment
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• 제11권4호
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• pp.257-274
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• 2020

There are many previous review articles are available to summarize either the characterization methods of effluent organic matter (EfOM) or the individual control treatment options. However, there has been no attempt made to compare in parallel the physicochemical treatment options that target the removal of EfOM from biological treatments. This review deals with the recent progress on the characterization of EfOM and the novel technologies developed for EfOM treatment. Based on the publications after 2010, the advantages and the limitations of several popularly used analytical tools are discussed for EfOM characterization, which include UV-visible and fluorescence spectroscopy, Fourier transform infrared spectroscopy (FTIR), size exclusion chromatography (SEC), and Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS). It is a recent trend to combine an SEC system with various types of detectors, because it can successfully track the chemical/functional composition of EfOM, which varies across a continuum of different molecular sizes. FT-ICR-MS is the most powerful tool to detect EfOM at molecular levels. However, it is noted that this method has rarely been utilized to understand the changes of EfOM in pre-treatment or post-treatment systems. Although membrane filtration is still the preferred method to treat EfOM before its discharge due to its high separation selectivity, the minimum requirements for additional chemicals, the ease of scaling up, and the continuous operation, recent advances in ion exchange and advanced oxidation processes are greatly noteworthy. Recent progress in the non-membrane technologies, which are based on novel materials, are expected to enhance the removal efficiency of EfOM and even make it feasible to selectively remove undesirable fractions/compounds from bulk EfOM.

• 한국CDE학회논문집
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• 제21권2호
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• pp.186-195
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• 2016

The finite element modeling of a ship for hull structural analysis on the basis of new harmonized common structural rules (CSR-H) is to be extended to the cargo holds in fore and after body of a ship. Unlike the parallel middle-body where the external and internal features of hull are equal along to the longitudinal direction of a ship, in fore and after body, the external and internal features of hull vary linearly or even irregularly in forms of a surface or a curve along to the longitudinal direction of a ship. Thus, it needs lots of design man-hours for the modeling for structural analysis. In order to save man-hours in initial structural design phase of a ship, the specified 3D CAD system has been adopted in shipbuilding industry. Through the interface between CAD and CAE (rule scantling and direct strength assessment), design man-hour in initial design phase can be saved even under the environment of CSR-H.

• 대한전자공학회논문지SD
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• 제44권2호
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• pp.86-94
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• 2007

네트워크-온-칩(NoC, network-on-chip) 기술은 SoC (system-on-a-chip) 설계에서 증가되는 온칩 통신의 복잡성을 해결하고 높은 확장성을 제공할 수 있는 기술이다. NoC를 이용한 설계는 많은 수의 IP들과 통신 네트워크들을 사용하기 때문에 동작이 복잡하고 설계 공간이 커서 많은 전력을 소모 한다. 그러나 기존의 분석적인 방법은 NoC응용의 큰 설계 공간 및 동작의 복잡성에 비해 상대적으로 간소화된 모델을 사용하여 현실적인 설계요소를 반영하지 못하거나 복잡한 시뮬레이션에 따른 많은 노력 및 시간 요구로 사용에 많은 제약이 있었다. 따라서 본 논문에서는 현실적이고 정확한 NoC의 전력 소모 분석을 위해 FPGA 프로토타입(prototype)을 개발하고 이에 대한 전력 소모를 분석을 할 수 있는 싸이클별 전력 소모 측정 기법 및 도구를 소개한다. 또한 사례 연구로서 NoC기술을 이용한 JPEG 압축기를 구현하고 이에 대한 전력 소모를 분석하여 그 효용성을 입증한다.

• 한국지진공학회논문집
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• 제7권1호
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• pp.41-55
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• 2003

상세한 지진해일 범람 현상을 규명하기 위하여 수립된 전회의 동적결합 차분 모형(Choi et al.)이 1983년 동해중부지진에 의한 지진해일 연구를 위해 우리나라 동해안 전역에 적용되었다. 계산영역은 격자의 크기가 다른 몇 개의 둥지영역이 평행하거나 경사가 진 방향으로 연결되어 구성되어 있다. 제일 안쪽의 둥지 영역은 해안을 따라 순차적으로 16영역으로 구성되었으며, 격자간격은 약 30m이다. 천수방정식(선형과 비선형)이 적용된 수치 시뮬레이션은 둥지영역의 격자크기에 따라 직각 또는 구면좌표계가 채택되었으며, 평행 및 경사 접합이 제일 안쪽의 둥지형 모형에 적용되었다. 시뮬레이션에 의한 결과는 지진해일 사상에 대한 처오름 높이의 관측치와 잘 일치하였다. 지진해일고 분포곡선의 개선이 수치적으로 연구되었으며, 지진원으로부터 거리가 먼 경우에는 대수정규분포를 따르는 경향을 보인다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.110-115
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• 2010

최근 도심지의 지하철 노선들은 과거에 지어진 지하철 노선들에 비하여 대심도 터널이 증대하고 있다. 신금호 역사(5호선, 깊이 : 46m)는 수도권에 있는 지하철 역사 중에서 3번째로 깊은 역사로서 대심도 역사의 모델로 선정되었으며, 신금호 전체 역사에 대한 화재시뮬레이션을 시도하였다. 신금호 역사는 3개의 출입구, 지하 1층 대합실, 지하 2층 대합실, 지하 2층에서 8층으로의 연결통로, 지하 8층 승강장으로 구성되어 있다. 본 연구에서는 지하 8층 승강장에서 지상 출입구 까지 전체 역사를 대상으로 연기거동을 해석하기 위하여 9,000,000개의 격자를 생성하였으며, 계산 효율을 증대시키기 위하여 19개의 블록으로 나누어서 처리하였다. 화재해석은 화재에 특화된 CFD 코드인 FDS를 사용하였으며 난류해석 기법은 LES가 사용되었다. MPI의 병렬처리기법을 이용하여 19개의 블록을 각각의 CPU에서 분산처리 하였다. 본 전산수치해석에 사용된 CPU 자원은 Intel 3.0 GHz Dual CPU 10개 (Core 20개)이다.

• 자원환경지질
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• 제2권1호
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• pp.13-33
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• 1969

The Mulkum mine, located in Mulkum-myon, Yangsan-Kun, Kyeongsang Province, is one of the biggest iron mine in Korea. The geology of this mine and its vicinity consists of Chusan andesitic rocks and Datae-dong andesite porphyry of the Kyeongsang System which were intruded by biotite granite widely distributed near the vicinity of Mulkum-ni. The ore deposits, embedded in Dotae-dong andesite porphyry, are fissure-filling vein type in origin. Up to present ore bodies of Main vein, No. 2 vein, Eastern No. 1, 2 vein and Western No. 1 vein are exploited. Generally the veins strike N 10-25 E and dip to 60-90 SE. The proved length of vein is more than 500 meters and its depth 150 meters in Main vein with 3-4 meters of thickness in average. Ore minerals are mainly magnetite and locally associated with small amounts of hematite, sphecularite and chalcopyrite. Gangue minerals are quartz, epidote, chlorite, pyroxene, and garnet, etc. The modes of occurrence of vein are as follow; 1. Branching and parallel vein patterns are observed around main shaft in -1 level. 2. Multiple cymoid loops and subrectangular vein patterns are observed around main shaft in -2 level. 2. Single vein patterns are observed in -3 and -5 level. The ore-shoots plunge northeasterly about 20-30 degrees. In conclusion, the tectonically fractured zone belongs to the poorly mineralized zone and shoots are formed as single vein type. The general trends of one-shoots must be applied the prospecting of the deep-seated ore body in the deposits.

• 센서학회지
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• 제19권2호
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• pp.99-111
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• 2010

This paper proposes an efficient hardware architecture to estimate disparities between 2D images for generating 3D depth images in a stereo vision system. Stereo matching methods are classified into global and local methods. The local matching method uses the cost functions based on pixel windows such as SAD(sum of absolute difference), SSD(sum of squared difference) and NCC(normalized cross correlation). The NCC-based cost function is less susceptible to differences in noise and lighting condition between left and right images than the subtraction-based functions such as SAD and SSD, and for this reason, the NCC is preferred to the other functions. However, software-based implementations are not adequate for the NCC-based real-time stereo matching, due to its numerous complex operations. Therefore, we propose a fast pipelined hardware architecture suitable for real-time operations of the NCC function. By adopting a block-based box-filtering scheme to perform NCC operations in parallel, the proposed architecture improves processing speed compared with the previous researches. In this architecture, it takes almost the same number of cycles to process all the pixels, irrespective of the window size. Also, the simulation results show that its disparity estimation has low error rate.

• 한국도로학회논문집
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• 제16권6호
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• pp.51-57
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• 2014

PURPOSES : An conventional method for electric power generation is converting thermal energy into mechanical energy then to electrical energy. Due to environmental issues such as global warming related with $CO_2$ emission etc., were the limiting factor for the energy resources which resulting in extensive research and novel technologies are required to generate electric power. Thermal energy harvesting using thermoelectric generator is one of energy harvesting technologies due to diverse advantages for new green technology. This paper presents a possibility of application of the thermoelectric generator's application in the direct exchange of waste solar energy into electrical power in road space. METHODS : To measure generated electric power of the thermoelectric generator, data logger was adopted as function of experimental factors such as using cooling sink, connection methods etc. Also, the thermoelectric generator、s behavior at low ambient temperature was investigated as measurement of output voltage vs. elapsed times. RESULTS : A few temperature difference between top an bottom of the thermoelectric generator is generated electric voltage. Components of an electrical circuit can be connected in various ways. The two simplest of these are called series and parallel and occur so open. Series shows slightly better performance in this study. An installation of cooling sink in the thermoelectric generator system was enhanced the output of power voltage. CONCLUSIONS : In this paper, a basic concepts of thermoelectric power generation is presented and applications of the thermoelectric generator to waste solar energy in road is estimated for green energy harvesting technology. The possibility of usage of thermoelectric technology for road facilities was found under the ambient thermal gradient between two surfaces of the thermoelectric module. An experiment results provide a testimony of the feasibility of the proposed environmental energy harvesting technology on the road facilities.