• Applied Microscopy
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• 제45권4호
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• pp.230-235
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• 2015

Crystallographic models are effective tools to interpret, calculate and even to predict the preferred crystallographic morphologies of precipitates in various precipitation systems. The present study gives an introduction on the recently developed secondary constrained coincident site lattice (II-CCSL) model. Using the II-CCSL model, the interface matching condition of the ${\beta}-Mg_{17}Al_{12}$ precipitates with ${\alpha}-Mg$ matrix in an aged AZ91 alloy has been analyzed to rationalize the morphologies of the precipitates. The results show that the characteristic crystallographic features of the observed ${\beta}-Mg_{17}Al_{12}$ precipitates, i.e., the habit plane of the ${\beta}-Mg_{17}Al_{12}$ lath with a Burgers orientation relationship (OR) and the growth direction of the ${\beta}-Mg_{17}Al_{12}$ with a Crawley OR exhibit a better lattice matching degree than their vicinal orientations. Moreover, the Crawley OR is preferred to the Burgers OR due to a better lattice match.

• 한국지반환경공학회 논문집
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• 제8권4호
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• pp.47-55
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• 2007

본 연구는 연약지반의 압밀특성을 나타내는 정수중 하나인 압밀계수($C_v$)를 결정하는데 있어 피에조 콘 관입시험(PCPT)결과의 적용성을 평가하고자 양산-물금지역의 연약지반에서 실시된 피에조 콘 관입시험 자료와 같은 지역 44개소에서 시추한 심도별로 총 172개 자연시료를 사용하여 기본적인 실내토질시험(압밀시험, Atterberg 한계시험, 입도분포시험 등)을 실시하였다. 각 시료의 압밀시험결과를 사용하여 Terzaghi(1943) 압밀 이론으로 구한 구속탄성계수(M) 및 압밀계수($C_v$)를 각 시료에 상응하는 현장 흙에서 실시한 피에조 콘 관입시험(PCPT) 결과로 구한 구속탄성계수 및 압밀계수와 비교분석하였다. 압밀시험으로 구한 구속탄성계수는 피에조 콘 관입시험으로 구한 구속탄성계수와 높은 상관성을 보였고 Jones & Rust(1995)가 제안한 경험식으로 계산된 구속탄성계수가 본 연구에서 피에조 콘 관입시험으로 구한 구속탄성계수와 유사한 값을 보였다. 압밀시험으로 구한 압밀계수와 콘 관입시험 결과로 구한 압밀계수는 직선적 관계를 보였고 콘 관입시험 결과로 구한 압밀계수 값은 압밀시험으로 구한 압밀계수 값의 54%정도로 나타났다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.212-213
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• 2021

As structure and the waterproofing material are compressed through the backfilling process after the waterproofing material is installed on the underground structure at the actual site, there is a difference between the behavioral response force of the waterproofing material in the compressed state and the behavioral response force in the non-constrained state. In this regard, we will analyze the limitations of the current structural behavioral response evaluation and suggest an improvement plan so that the future test and evaluation environment can be evaluated under conditions similar to the field.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.196-203
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• 2022

The resource constrained scheduling problem (RCSP) constitutes one of the most challenging problems in Project Management, as it combines multiple parameters, contradicting objectives (project completion within certain deadlines, resource allocation within resource availability margins and with reduced fluctuations), strict constraints (precedence constraints between activities), while its complexity grows with the increase in the number of activities being executed. Due to the large solution space size, this work investigates the application of Genetic Algorithms to approximate the optimal resource alolocation and obtain optimal trade-offs between different project goals. This analysis uses the cost of exceeding the daily resource availability, the cost from the day-by-day resource movement in and out of the site and the cost for using resources day-by-day, to form the objective cost function. The model is applied in different case studies: 1 project consisting of 10 activities, 4 repetitive projects consisting of 40 activities in total and 16 repetitive projects consisting of 160 activities in total, in order to evaluate the effectiveness of the algorithm in different-size solution spaces and under alternative optimization criteria by examining the quality of the solution and the required computational time. The case studies 2 & 3 have been developed by building upon the recurrence of the unit/sub-project (10 activities), meaning that the initial problem is multiplied four and sixteen times respectively. The evaluation results indicate that the proposed model can efficiently provide reliable solutions with respect to the individual goals assigned in every case study regardless of the project scale.

• 국제초고층학회논문집
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• 제7권1호
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• pp.33-46
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• 2018

The Case Study prepared by PCPA and Lift Group will identify a growing development problem in urban areas; high value project sites that are restrictive in size or "tight" are underutilized and underdeveloped. In an effort to remedy this problem, our team will evaluate a design program through the lens of both conventional construction and Core Cantilever Construction. It is also important to differentiate between Core Cantilever construction and the plagued "Lift Slab" construction method as they may be confused, due to the top down construction sequence. This article will demonstrate that constraints inherent to conventional construction techniques prohibit economically viable development of these project sites, while Core Cantilever construction methods increase the projects value by reducing construction timelines and increasing the useable floor area.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.328-330
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• 2005

This paper presents a transfer capability enhancement of using VSC HVDC system which can control reactive power as well as active power. The transfer capability is constrained by stability like voltage stability. These constraints may relieved by reactive power control ability of the VSC HVDC system. Site selection algorithm is also proposed.

• 한국정보과학회논문지:정보통신
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• 제31권1호
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• pp.91-100
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• 2004

본 논문은 제한된 메모리를 가진 모바일 수신자를 고려한 무선 상태 적응적인 TCP 흐름 제어방법을 제안한다. 수신자에 의한 TCP 흐름 제어는 수신자에서 Advertised 윈도우를 조정함으로써 수행된다 제안된 방법은 수신자가 사용 가능한 무선 대역폭과 패킷 전송 지연 시간을 동적으로 측정하며, 측정된 정보를 기반으로 Advertised 윈도우를 적절히 조정한다. 무선 상태를 반영한 Advertised 윈도우의 조정으로 인해 송신자의 전송 성능 향상과 종단간 패킷 전송 지연 시간을 줄일 수 있다. 제안된 방법은 수신자에서의 TCP 변경만으로 구현될 수 있고 송신자나 중간 라우터의 변경을 필요로 하지 않는다. 제안된 방법의 구현과 CDMA2000 1x 환경에서의 실험을 통해 수신자 버퍼 크기가 2896 Bytes일 경우, 흐름 제어를 사용할 때가 기존 방식보다 전송률을 약 5배 향상시킬 수 있음을 보인다. 또한, 수신자 버퍼 크기가 64 KBytes일 경우 흐름 제어를 사용할 때가 기존 방식보다 때보다 종단간 패킷 왕복 시간은 반 이하로 줄일 수 있음을 보인다.

• Wind and Structures
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• 제14권4호
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• pp.337-357
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• 2011

The collection of wind speed time series by means of digital data loggers occurs in many domains, including civil engineering, environmental sciences and wind turbine technology. Since averaging intervals are often significantly larger than typical system time scales, the information lost has to be recovered in order to reconstruct the true dynamics of the system. In the present work we present a simple algorithm capable of generating a real-time wind speed time series from data logger records containing the average, maximum, and minimum values of the wind speed in a fixed interval, as well as the standard deviation. The signal is generated from a generalized random Fourier series. The spectrum can be matched to any desired theoretical or measured frequency distribution. Extreme values are specified through a postprocessing step based on the concept of constrained simulation. Applications of the algorithm to 10-min wind speed records logged at a test site at 60 m height above the ground show that the recorded 10-min values can be reproduced by the simulated time series to a high degree of accuracy.

• Architectural research
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• 제25권1호
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• pp.11-17
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• 2023

This study aims to derive key construction supervision work that can be digitalized among construction supervision work. The scope of the study includes domestic construction sites to which the Building Act of South Korea is applied. First, the construction supervision process was identified through extensive consultation of construction expert witnesses. Afterwards, the key construction supervision works for digitization were derived through survey results construction expert witnesses. Among the 24 supervision works throughout the pre-construction, construction, and post-construction stages, the proportion of supervision work manpower or cost, the type of data generated by supervision work and the urgency of introducing digital technology, and the impact on productivity and safety of supervision work were evaluated on a 5-point scale from "very low" to "very high" was investigated. The survey was conducted by t-test analysis, and as a result, it was possible to derive that the level of digitization was higher than average in "quality management," "safety management," and "collection and cooperation of maintenance instructions." It can be interpreted that digitization has been introduced on a pilot testing basis or has already been completed according to the needs of the site. On the other hand, it can be interpreted that the work that are obtained below the average score are considered to be realistically constrained at the construction site and that it is inevitable for the supervisor to proceed manually. Future studies include analyzing the quantitative impact of the key construction supervision work once digitalization is fully applied.

• 한국지리정보학회지
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• 제12권4호
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• pp.136-145
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• 2009

지반특성은 지진동, 액상화 및 산사태 등으로 인한 지질재해 위험성 평가에서 중요한 요소로 사용될 수 있다. 일반적으로 지역적 지반특성을 규명하기 위한 지반분류에서는 시추나 탄성파 탐사를 이용하는 방법을 많이 사용하나, 이번 연구에서는 지질도와 지형도를 활용하였다. 본 연구에서는 수치지질도로부터 지질시대와 암상 자료를 추출하고, 지형도로부터는 고도와 경사도 자료를 추출한 후 GIS를 사용하여 경상남북도 지역의 지반을 분류하였다. 그 결과 연구지역의 지반은 지반분류 B(보통암)가 우세하게 나타나며, 하천과 매립지 부근에서는 이보다 연약한 지반으로 이루어져 있다. 이 결과를 연구지역의 시추자료를 사용한 지반분류와 비교해보면 약 73% 정도 일치한다. 오차원인은 주로 지질도 혹은 지형도에서 기인한다고 사료되며, 일부는 시추작업과 현장조사를 통해 직접적인 오류원인을 찾아야 하는 경우도 있다. 이 연구 결과는 지진, 홍수, 사태 및 액상화 등의 지질재해 및 토지이용계획 수립 시 유용한 자료로 사용될 수 있을 것이다.