• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1999년도 가을 학술발표회 논문집
• /
• pp.87-94
• /
• 1999

Sand drain as a vertical drainage is widely used in soft ground improvement. Recently, sand, the principal source of sand drain, is running out. A laboratory model test was carried out to utilize gravel as a substitute for sand. Though which the characteristics of gravel are compared to those of sand for engineering purpose. Two cylindrical containers for the model test were filled with marine clayey soil from the west coast of Korea with a column in the center, one with sand, the other with gravel. Vibrating wire type piezometers were installed at the distance of 1.0D, 1.5D and 2.0D from the center of the column. D is the diameter of the column. The transient process of pore water pressure with loading and the characteristics of consolidation were studied with the data gained from the measuring instrument place on the surface of the container. The parameter study was performed for the marine clayey soil before and after the test in order to check the effectiveness of the improvement. The clogging effect was checked at various depth in gravel column after the test. According to the test, the settlement was found to be smaller in gravel drain than in sand drain. The increase in bearing capacity by gravel pile explains the result. The clogging effect was not found in gravel column. As a result, it is assumed that gravel is relatively acceptable as a drainage material.

• 소음진동
• /
• 제4권1호
• /
• pp.33-42
• /
• 1994

When a vibration is generated due to the misalignment, the reduction of the vibration level is not attainable unless a correct shaft alignment is conducted. In a turbine system, an alignment procedure requires quite a lot amount of expense and time. To reduce this effort, an algorithm of the turbine alignment is developed to be used in the computer program. The program consists of five parts : input, calculation, display of the results, file management, and printer output. In the input part, users must provide the data on the turbine number, the reference value of the alignment, and the number of the feet of the generator. In calculation, the moving distance of the bearing and the necessary amount of the shims are calculated. In the display and the output parts, the calculated results are displayed and calculated. In the display and the output parts, the calculated results are displayed and printed. Then, by using the file management, results and procedures conducted are saved in the floppy diskette or in the hard disk. The developed program can be run in IBM PC compatible with more than 640 KB of main memory with the operating system of MS-DOS v 3.3 or higher. It is developed for novice users with no experience or specialty in this field. The program is not only useful in the power plant application, but also helpful for recording of the alignment procedures.

• Earthquakes and Structures
• /
• 제11권4호
• /
• pp.701-721
• /
• 2016

Base isolation is a well-established passive strategy for seismic response control of buildings. In this paper, an efficient framework is proposed for reliability-based design optimization (RBDO) of isolated buildings subjected to uncertain earthquakes. The framework uses reduced function evaluations method, as an efficient tool for structural reliability analysis, and an efficient optimization algorithm for optimal structural design. The probability of failure is calculated considering excessive base displacement, superstructure inter-storey drifts, member stress ratios and absolute accelerations of floors of the isolated building as failure events. The behavior of rubber bearing isolators is modeled using nonlinear hysteretic model and the variability of future earthquakes is modeled by applying a probabilistic approach. The effects of pulse component of stochastic near-fault ground motions, fixity-factor of semi-rigid beam-to-column connections, values of isolator parameters, earthquake magnitude and epicentral distance on the performance and safety of semi-rigidly connected base-isolated steel framed buildings are studied. Suitable RBDO examples are solved to illustrate the results of investigations.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2005년도 춘계 학술발표회 논문집
• /
• pp.286-293
• /
• 2005

In soft ground the settlement criterion usually governs. Therefore, it is very important not only reasonable assessment of the allowable bearing capacity of the soil but also reasonable assessment of settlement. In the previous studies by many other researchers, load concentration ratio and settlement reduction factor are usually proposed for estimating the settlement of granular compaction piles. In the previous studies, the reinforced ground with granular compaction piles is simplified as composite ground and the analysis is performed with in the basis of this assumption. However, the lateral deformation of granular compaction pile could not be considered and only the relative vertical strength between pile and soils could be considered in the analysis. In this study, a method adapting the Tresca failure criterion is proposed for calculating settlement of granular compaction pile. Proposed method can be considered the strength of pile material, pile diameter, installing distance of pile and the deformation behavior of vertical and horizontal directions of pile. In the presented study, large-scale field load test is performed and the results are described. Also, predictions of settlements from the proposed method are compared with the results of the load test. In addition, a series of parametric study is performed and the design parameters are analyzed.

• 융합보안논문지
• /
• 제6권3호
• /
• pp.37-47
• /
• 2006

본 논문에서는 필립스사의 지자기센서를 블루투스 통신시스템에 연결하여 방위각을 $5^{\circ}$ 단위로 전후 방향으로 기울기 각도를 변화시켜 $360^{\circ}$를 측정하였다. 측정된 방위값은 100M 이내에서 이동하면서 측정값을 블루투스 통신시스템으로 전송하여 측정값을 분석하였다. 블루투스를 이용하여 전파 장애가 없는 평지에서 직선거리 100M 이내에서 방위 측정값은 에러 없이 전송할 수 있었다. 지자기센서를 수평을 유지하면 98%의 신뢰를 가지는 방위측정값을 얻었다. 본 연구를 바탕으로 기울기를 가지는 지형을 이동하는 이동형 지능로봇에 장착 정확도가 향상된 방위 측정값을 전송하여 이동형 로봇의 방위추적을 할 수 있다.

• 천문학회지
• /
• 제29권spc1호
• /
• pp.111-118
• /
• 1996

We review observational evidence bearing on the formation of a prototypical large spiral galaxy, the Milky Way. New ground- and space-based studies of globular star clusters and dwarf spheroidal galaxies provide a wealth of information to constrain theories of galaxy formation. It appears likely that the Milky Way formed by an combination of rapid, dissipative collapse and mergers, but the relative contributions of these two mechanisms remain controversial. New evidence, however, indicates that initial star and star cluster formation occurred simultaneously over a volume that presently extends to twice the distance of the Magellanic Clouds.

• 한국안전학회지
• /
• 제15권2호
• /
• pp.1-7
• /
• 2000

This paper presents the approach involving fault detection and diagnosis of gears using pattern recognition and Wavelet transform. It describes result of the comparison between KDI (Kullback Discrimination Information) with the nearest neighbor classification rule as one of pattern recognition methods and Wavelet transform to know a way to detect and diagnosis of gear damages experimentally. To model the damages 1) Normal (no defect), 2) one tooth is worn out, 3) All teeth faces are worn out 4) One tooth is broken. The vibration sensor was attached on the bearing housing. This produced the total time history data that is 20 pieces of each condition. We chose the standard data and measure distance between standard and tested data. In Wavelet transform analysis method, the time series data of magnitude in specified frequency (rotary and mesh frequency) were earned. As a result, the monitoring system using Wavelet transform method and KDI with nearest neighbor classification rule successfully detected and classified the damages from the experimental data.

• Asian-Australasian Journal of Animal Sciences
• /
• 제21권11호
• /
• pp.1535-1543
• /
• 2008

Microsatellites (MS) are useful for quantifying genetic variation within and between populations and for describing the evolutionary relationships of closely related populations. The main objectives of this work were to estimate genetic parameters, measure genetic distances and reconstruct phylogenetic relationships between Australian Angora/Angora_Aus/ and Cashmere/Cashmere_Aus/ populations and three Mongolian Cashmere goat (Bayandelger/BD/, Zavkhan Buural/ZB/, and Gobi Gurvan Saikhan/GGS/) populations based on variation at fourteen MS loci. The level and pattern of observed and expected heterozygosity and polymorphic information content of the fourteen loci studied across the populations were quite similar and high. Except for SRCRSP07, all studied microsatellites were in Hardy-Weinberg Equilibrium (p<0.001). Moderate genetic variation (7.5%) was found between the five goat populations with 92.5% of total genetic variation attributable to diversity existing between the individuals within each population. The greatest Nei's genetic distances were found between the Angora and four Cashmere populations (0.201-0.276) and the lowest distances were between the Mongolian Cashmere goat populations (0.026-0.031). Compared with other Cashmere goat populations, the GGS (crossbred with Russian Don Goats) population had the smallest pairwise genetic distance from the Australian Angora population (0.192). According to a three-factorial correspondence analysis (CA), the three different Mongolian Cashmere populations could hardly be distinguished from each other.

• 전기전자학회논문지
• /
• 제24권3호
• /
• pp.814-820
• /
• 2020

현재까지의 M진 DCSK 시스템에서 M이 증가함에 따라 성상도 신호점 사이의 거리는 더 가까워져서 성능이 저하된다. 본 논문에서는 비트 오류율 (BER) 성능을 향상시키기 위해 펄스위치변조 및 DCSK를 기반으로 하이브리드 변조 방식을 제안한다. 비트의 한 부분은 PPM에 의해 변조되고 다른 부분은 DCSK에 의해 변조된다. 따라서 정보 베어링 신호는 정보 비트 및 추가 정보 비트에 의해 결정되는 PPM의 선택된 펄스 위치에 따라 동시에 변조된다. 제안된 방식은 BER 성능은 시뮬레이션에 의해 도출되고 검증된다. 결과는 논문에서 제안한 방식이 부가적인 백색 가우시안 잡음 및 다중 경로 레일리 페이딩 채널에서 기존의 M-DCSK, 코드 인덱스 변조 DCSK 및 정류 코드 인덱스 DCSK를 능가한다는 것을 보여준다.

• Steel and Composite Structures
• /
• 제1권1호
• /
• pp.97-110
• /
• 2001

Architectural steel structures with visible tension and compression members are becoming more prevalent as a popular form of construction that reflects the nature of the resistance to the applied loads. These members require the use of structural steel pins at their ends to ensure either axial tension or axial compression in the members. Structural pins have been used as a means of connection for centuries and it would appear that their behaviour is relatively well understood. However, the rules for the design of pins vary quite considerably from code to code and this has caused some confusion amongst consulting structural engineers operating internationally. To provide some insight into this problem, a comprehensive testing program has been carried to examine the influence of parameters such as pin diameter, material properties of the pin, thickness of the loading plates, material properties of the loading plates and the distance of the pin to the edge of the loading plates. The modes of failure have been carefully examined. Based on this study, modifications to current design procedures are proposed that properly take into account the different possible modes of failure.