• 국제학술발표논문집
• /
• The 1th International Conference on Construction Engineering and Project Management
• /
• pp.1181-1186
• /
• 2005

In many construction projects, progress and efficiency are hampered by poor communication of discipline-specific models. For example, architects use 2D or 3D CAD models and builders use CPM diagrams, Gantt charts, and spreadsheets to show their view of the project. Nowadays, advanced computer visualization tools, 4D CAD or VR, can show these disparate models to understand cross-disciplinary impacts of design and construction decisions. In Korea, several leading companies have tried to apply these tools to their pilot projects from the design phase to the maintenance phase. These companies have expected that more project stakeholders could understand a construction schedule more quickly and completely with 4D visualization than with the traditional construction management tools. However, modeling of the 4D CAD or VR can be quite time-consuming and expensive to generate manually and has therefore limited the spread and use of these models. In order to adopt widely those models in construction industry, the areas that those tools could support to take large benefits in diverse functional areas of construction management need to be analyzed. In this study, researchers analyze the usefulness and limitations of the 4D models and VR in the construction industry, develop the strategy of application priority, and improve the 4D modeling method.

• Design & Manufacturing
• /
• 제18권2호
• /
• pp.51-56
• /
• 2024

In this study, a tool was developed for analyzing production lead time in turning operations. It is expected to help to reduce machining time and to identify, for example, tool change intervals. The tool was developed using Visual Basic.Net and features a user-friendly graphical user interface (GUI) that allows users to easily input cutting conditions and calculate the usage time and feeding distance for each cutting tool based on a G-code program. Object-oriented programming techniques were also used to encapsulate and classify complex logic, thereby efficiently organizing and managing the functions and data structures of this analysis tool. The analysis tool provides various outputs. It calculates the use time of each detailed process of the turning operation, the use time of each tool, the use time of each type of feeding, and also generates the data needed for cutting time analysis, which can be visualized in charts. The analysis tool developed in this study is expected to significantly contribute to improving the efficiency of manufacturing processes and increasing productivity, particularly, in the manufacturing of components requiring massive material removal, such as aircraft parts.

• Earthquakes and Structures
• /
• 제9권4호
• /
• pp.831-849
• /
• 2015

Seismic-design procedures for walls require that the confinement in the critical (plastic hinge) regions should extend over a length in the compression zone of the cross section at the wall base where concrete strains in the Ultimate Limit State (ULS) exceed the limit of 0.0035. In a performance-based framework, confinement is linked to required curvature ductility so that the drift demand at the performance point of the structure for the design earthquake may be met. However, performance of flexural walls in the recent earthquakes in Chile (2010) and Christchurch (2011) indicates that the actual compression strains in the critical regions of many structural walls were higher than estimated, being responsible for several of the reported failures by toe crushing. In this study, the method of estimating the confined region and magnitude of compression strain demands in slender walls are revisited. The objective is to account for a newly identified kinematic interaction between the normal strains that arise in the compression zone, and the lumped rotations that occur at the other end of the wall base due to penetration of bar tension yielding into the supporting anchorage. Design charts estimating the amount of yield penetration in terms of the resulting lumped rotation at the wall base are used to quantify the increased demands for compression strain in the critical section. The estimated strain increase may exceed by more than 30% the base value estimated from the existing design expressions, which explains the frequently reported occurrence of toe crushing even in well confined slender walls under high drift demands. Example cases are included in the presentation to illustrate the behavioral parametric trends and implications in seismic design of walls.

• Journal of the Korean Data and Information Science Society
• /
• 제28권2호
• /
• pp.339-348
• /
• 2017

전통적인 통계적 공정관리에서 품질특성치의 위치모수와 척도모수의 변화를 탐지하는 것은 주된 관심사였고, 이를 위해 일반적으로 두 개의 관리도를 병행하여 사용한다. 그러나 하나의 관리도를 사용하여 두 모수의 변화를 동시에 탐지하는 절차에 대한 연구도 많이 진행되어 왔다. 하나 또는 두 개의 관리도를 사용할 때, 제1국면 (phase I)을 통하여 모수를 추정하여 관리한계를 설정하여 제2국면(phase II)의 관리도를 운영하는데 이때 정규성 가정의 만족 여부는 아주 중요한 점검 사항이다. 실제 공정에서는 종종 분포에 대한 가정을 하기 어렵거나 정규분포를 따른다고 가정하기 어려운 경우가 있는데, 이러한 경우에는 비모수적 관리도를 사용할 수 있다. 이 논문에서는 비모수적 관리도이면서, 하나의 관리도를 사용하여 위치모수와 척도모수의 변화를 탐지하는 Shewhart-Lepage 관리도를 소개하고, 위치모수와 척도모수가 동시에 변화할 때 진단 단계에서 변화의 원인을 가장 정확하게 진단할 수 있는 최적의 진단한계를 모의실험을 통해 제시하고 그 효율에 대해 연구하였다.

• Earthquakes and Structures
• /
• 제24권6호
• /
• pp.455-475
• /
• 2023

The present study investigates the non-linear soil-pile interaction using three-dimensional (3D) non-linear finite element models. The numerical models were validated by using the results of extensive pile load and shaking table tests. The pile performance in liquefiable and non-liquefiable soil has been studied by analyzing the liquefaction ratio, pile lateral displacement (LD), pile bending moment (BM), and frictional resistance (FR) results. The pile models have been developed for the different ground conditions. The study reveals that the results obtained during the pile load test and shaking cycles have good agreement with the predicted pile and soil response. The soil density, peak ground acceleration (PGA), slenderness ratio (L/D), and soil condition (i.e., dry and saturated) are considered during modeling. Four ground motions are used for the non-linear time history analyses. Consequently, design charts are proposed depended on the analysis results to be used for design practice. Eleven models have been used to validate the capability of these charts to capture the soil-pile response under different seismic intensities. The results of the present study demonstrate that L/D ratio slightly affects the lateral displacement when compared with other parameters. Also, it has been observed that the increasing in PGA and decreasing L/D decreases the excess pore water pressure ratio; i.e., increasing PGA from 0.1 g to 0.82 g of loose sand model, decrease the liquefaction ratio by about 50%, and increasing L/D from 15 to 75 of the similar models (under Kobe earthquake), increase this ratio by about 30%. This study reveals that the lateral displacement increases nonlinearly under both dry and saturated conditions as the PGA increases. Similarly, it is observed that the BM increases under both dry and saturated states as the L/D ratio increases. Regarding the acceleration histories, the pile BM was reduced by reducing the acceleration intensity. Hence, the pile BM decreased to about 31% when the applied ground motion switched from Kobe (PGA=0.82 g) to Ali Algharbi (PGA=0.10 g). This study reveals that the soil conditions affect the relationship pattern between the FR and the PGA. Also, this research could be helpful in understanding the threat of earthquakes in different ground characteristics.

• Earthquakes and Structures
• /
• 제3권2호
• /
• pp.141-168
• /
• 2012

The Retrofit Yield Spectrum (RYS) is a new spectrum-based device that relates seismic demand of a retrofitted structure with the fundamental design parameters of the retrofit. This is obtained from superposition of Yield Point Spectra with design charts that summarize in pertinent spectrum-compatible coordinates the attributes of a number of alternative retrofit scenarios. Therefore, once the requirements for upgrading a given structure have been determined, the RYS enable direct insight of the sensitivity of the seismic response of the upgraded structure to the preliminary design decisions made while establishing the retrofit plan. By virtue of their spectrum-based origin, RYS are derived with reference to a single mode of structural vibration; a primary objective is to control the contribution of this mode in the retrofit design so as to produce a desirable distribution of damage at the ultimate limit state by removing soft storey formations and engaging the maximum number of structural members in deformation, in response to the input motion. Calculations are performed with reference to the yield-point, where secant stiffness is proportional to the flexural strength of reinforced concrete members. Derivation and use of the Retrofit Yield Spectra (RYS) refers to the seismic demand expressed either in terms of spectral acceleration, spectral displacement or interstory drift, at yield of the first storey. A reinforced concrete building that has been tested in full scale to a sequence of simulated earthquake excitations is used in the paper as a demonstration case study to examine the effectiveness of the proposed methodology.

• 한국지반공학회논문집
• /
• 제15권1호
• /
• pp.15-29
• /
• 1999

본 연구에서는 GRS-RW 공법의 전면부벽체 배면으로부터 다양한 거리만큼 이격되어 등분포상 재하중이 작용하는 경우, 이러한 인접상재하중의 영향을 고려한 횡토압 예측방법을 한계평형해석에 의해 제시하였으며, GRS-RW 공법의 설계시 참고할 수 있는 예비설계(preliminary design)용 설계 도표를 제시하였다. 제시된 토압 합력의 예측방법은, 전면부벽체 배면으로부터 상재하중이 작용하는 지점까지의 수평거리를 고려할 수 있도록 하였으며, 지진하중 작용시 전면부벽체 및 뒷채움 자중에 의한 수평.연직관성력의 영향을 고려하였다. 아울러. 본 연구제시 해석법은, 점성토뒷채움의 경우에 흔히 적용되는 복합지오텍스타일 보강토공법의 해석시에 추후 적용 가능하도록 점착력이 있는 뒷채움(c-$\phi$ soil)에서 발생 가능한 인장균열의 영향을 고려할 수 있도록 하였다. 본 연구제시 해석방법의 효율성 및 적합성 등을 확인하기 위한 다양한 분석결과, 상재하중 이격거리비가 약 0.60~0.70 이상인 경우에는, 특히 상재하중의 크기 및 설계수평진도가 증가할수록, 또는 보강재의 연직간격이 0.3, 0.4m로 비교적 작은 경우에는, Jarquio의 수정 Boussinesq방정식을 이용한 토압 계산방식의 적용시 불안전측의 설계가 될 수 있는 것으로 나타났다. 본 연구에서 제시된 해석방법은, 전면부벽체의 경사가 연직인 경우로 한정하였다.

• 물과 미래
• /
• 제21권4호
• /
• pp.389-397
• /
• 1988

남해 연안 지상측정소의 과거풍속자료와 돌풍 기록으로 부터 과거의 피해 자료를 추산(Hindcasting)하고 이로부터 얻어진 지역별 피해별 연간 최대피해의 극치 계열로 부터 확율분석을 통하여 송해 설계치를 결정하는 방법이 제안되엇다. 남해 연안에 내재하는 큰 파급은 돌풍과 춘하절 계절풍에 의해 생성되며 지역별 파향별로 상당한 차이를 보인다. 재현기간이 100년인 설계 유의파의 파고는 송해에서 4.6m~ 8.8m ,조기는 8.2sec~ 12.9sec의 범위를 보인다. 남해\ulcorner\ulcorner에서 풍속 $U_1$ >15m/s의 강풍에 대하여 일반적으로 해상풍속(Uw)은 \ulcorner\ulcorner 지상관측소 풍속($U_1$)의 0.8~0.9배 정도를 나타낸다. 남해 \ulcorner\ulcorner의 지상관측소에서 지속기간의 평균풍속($U_1$)은 2$U_{10}$)의 0.7~0.9배의 값을 가지면서 역지수 함수적으로 감소한다.

• 한국소음진동공학회논문집
• /
• 제20권10호
• /
• pp.983-990
• /
• 2010

Reduction of acoustic loads of space launch vehicles can be achieved by acoustic absorbers satisfying strict cleanness requirements. This limited the use of general porous materials and requires non-porous sound absorbers. Micro-perforated panel absorbers(MPPA) is one of promising sound absorbers satisfying the cleanness requirement for launch vehicles. However, its applicability was limited to low sound pressure levels according to the acoustic impedance model of micro-perforated panels. In this paper the applicability of micro-perforated panel absorbers at high incident sound pressure was investigated in experimental ways. The absorption characteristics of a micro-perforated panel absorber was simulated according to its design variables, e.g., minute hole diameters and aperture ratios. It was shown that optimal design can be readily done by using proposed design charts. Experiments were conducted to measure acoustic properties of the designed micro-perforated panel absorbers. The results showed that acoustic resistance increases rapidly as incident sound pressure level does but change of acoustic reactance can be neglected in a practical point of view. This caused the decrease of peak value of absorption coefficient at high incident sound pressure level, but the amount of reduction can be accepted in practice. The major advantage of the micro-perforated panel absorber(wide absorption bandwidth) was still kept at high sound pressure level.

• 인터넷정보학회논문지
• /
• 제22권4호
• /
• pp.65-82
• /
• 2021

A well-designed website is mandatory for good marketing and proper tourism business. This research considers Nepal as a domain of study and specifically explores welcomenepal.com, the official tourism portal as a reference for the study. The work is based on the study of the existing literature, user-survey, and technical testing of the website using open-source testing tools to identify user perspective, design issues, website architecture and design quality of the tourism website. A population size of 400 respondents, which consist of both domestic and international tourist, are considered for the survey. Data is received from 360 respondents, which is analyzed using statistical tests like Cronbach's alpha, Pearson's correlation, cross-tabulations, bars charts and graphs to draw inferences and consclusion. The software-based test results serve as another important parameter for the evaluation of the current official website. This study brings out core needs of the tourist in terms of expectations from a tourism website and access technical quality of the current portal to provide necessary feedback and suggestions. The government officials, business houses, and web designers can utilize this work as a knowledge base to build tourism websites, which are user-centric. Further, the work is specifically important for Nepal government and tourism officials to identify shortcomings in their current website and make improvements for better design and user adaptability in future.