• 한국환경과학회지
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• 제31권4호
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• pp.329-339
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• 2022

Better understanding the mechanism of black ice occurrence on the road in winter is necessary to reduce the socio-economic damage it causes. In this study, intensive observations of road weather elements and surface information under the influence of synoptic high-pressure patterns (22^nd December, 2020 and 29^th January, and 25^th February, 2021) were carried out using a mobile observation vehicle. We found that temperature and road surface temperature change is significantly influenced by observation time, altitude and structure of the road, surrounding terrain, and traffic volume, especially in tunnels and bridges. In addition, even if the spatial distribution of temperature and road surface temperature for the entire observation route is similar, there is a difference between air and road surface temperatures due to the influence of current weather conditions. The observed road temperature, air temperature and air pressure in Nongong Bridge were significantly different to other fixed road weather observation points.

• Smart Structures and Systems
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• 제29권1호
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• pp.181-193
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• 2022

Data-driven structural health monitoring (SHM) of civil infrastructure can be used to continuously assess the state of a structure, allowing preemptive safety measures to be carried out. Long-term monitoring of large-scale civil infrastructure often involves data-collection using a network of numerous sensors of various types. Malfunctioning sensors in the network are common, which can disrupt the condition assessment and even lead to false-negative indications of damage. The overwhelming size of the data collected renders manual approaches to ensure data quality intractable. The task of detecting and classifying an anomaly in the raw data is non-trivial. We propose an approach to automate this task, improving upon the previously developed technique of image-based pre-processing on one-dimensional (1D) data by enriching the features of the neural network input data with multiple channels. In particular, feature engineering is employed to convert the measured time histories into a 3-channel image comprised of (i) the time history, (ii) the spectrogram, and (iii) the probability density function representation of the signal. To demonstrate this approach, a CNN model is designed and trained on a dataset consisting of acceleration records of sensors installed on a long-span bridge, with the goal of fault detection and classification. The effect of imbalance in anomaly patterns observed is studied to better account for unseen test cases. The proposed framework achieves high overall accuracy and recall even when tested on an unseen dataset that is much larger than the samples used for training, offering a viable solution for implementation on full-scale structures where limited labeled-training data is available.

• Geomechanics and Engineering
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• 제33권1호
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• pp.29-40
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• 2023

Xanthan gum and starch compound biopolymer (XS), an environmentally friendly soil-binding material produced from natural resources, has been suggested as a slope protection material to enhance soil strength and erosion resistance. Insufficient wet strength and the consequent durability concerns remain, despite XS biopolymer-soil treatment showing high strength and erosion resistance in the dried state, even with a small dosage of soil mass. These concerns need to be solved to improve the field applicability and post-stability of this treatment. This study explored the utilization of an alkaline-based cation crosslinking method using calcium hydroxide and sodium hydroxide to induce non-thermal gelation, resulting in the enhancement of the wet strength and durability of biopolymer-treated soil. Laboratory experiments were conducted to assess the unconfined compressive strength and cyclic wetting-drying durability performance of the treated soil using a selected recipe based on a preliminary gel formation test. The results demonstrated that the uniformity of the gel structure and gelling time varied depending on the ratio of crosslinkers to biopolymer; consequently, the strength of the soil was affected. Subsequently, site soil treated with the recipe, which showed the best performance in indoor assessment, was implemented on the field slope at the bridge abutment via compaction and pressurized spraying methods to assess feasibility in field implementation. Moreover, the variation in surface soil hardness was monitored periodically for one year. Both slopes implemented by the two construction methods showed sufficient stability against detachment and scouring, with a higher soil hardness index than the natural slope for a year.

• 한국전자통신학회논문지
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• 제18권4호
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• pp.617-624
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• 2023

최근, 전자 제품의 소형화와 저소비전력화 및 향상된 효율과 역률개선이 큰 관심 사항이 되고 있다. 본 논문에서는 PWM 제어기반의 AC-DC 컨버터를 설계, 제작하였다. AC-DC 컨버터는 하나의 정류회로와 하나의 출력전압 제어 회로가 직렬로 연결되는 구조로 설계하였으며, 정류회로는 다이오드 기반 단상 전파전류 회로, 출력전압 제어 회로는 PWM 제어기반의 DC-DC 변환 회로를 적용하였다. PWM 제어를 위한 주 제어장치로 아두이노를 이용하였으며, LCD를 출력 단에 구성하여 제어 결과를 확인할 수 있도록 하였다. 시험회로를 통한 반복 실험들을 통해서 오실로스코프와 LCD에 디스플레이 되는 출력전압과 목표 출력전압의 오차를 확인하였으며, 오실로스코프 측정값을 기준으로 약 5%의 오차율을 보임으로써 제안된 설계 방법론의 유효성을 확인할 수 있었다.

• 한국과학예술포럼
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• 제24권
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• pp.375-388
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• 2016

본 연구는 애니메이션 '알라딘' 'A Whole New World'의 OST와 VST의 융합분석을 수행한 것이다. OST는 도입단계, 경과단계, 클라이막스단계, 엔딩단계의 4단계로 분류되고 각 단계마다 OST와 VST의 특징이 발견되었다. 특히, 클라이막스단계에서는 OST요소(사운드, 조성, 템포, 주요 음역, 셈여림, 악기편성)와 VST요소(영상구도, 카메라 샷, 카메라 움직임)의 높은 다이나믹 특성이 발견되었다. FS는 47.9% 사용되었는데, 이는 사랑의 완성단계에 두 캐릭터가 하나가 되는 것을 보여 주는데 도움을 준다. 이것은 이전 연구인 '미녀와 야수' OST의 공통점이기도 하다. '미녀와 야수'에서는 악기가 캐릭터와 매칭되고 '알라딘'에서는 화면 내 물체의 고저위치와 상승하강에 악기를 매칭하는 특징을 가진다.

• 대한토목학회논문집
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• 제30권2A호
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• pp.113-120
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• 2010

콘크리트 충전강관을 이용한 교량은 새로운 형식의 교량 형태이다. 강관을 이용한 교량을 적용하는데 있어서 가장 중요한 것은 이음부의 설계이다. 이 논문에서는 축하중을 받는 충전강관 N형 이음부에서 현재는 충전강관으로 브레이스는 강관으로 구성된 이음부의 특성을 범용 프로그램인 ABAQUS를 이용하여 유한요소해석을 통해 고찰하였다. 충전강관 이음부의 핫스폿 응력을 결정하는 기하학적 인자 중, 용접 각장길이, 현재의 직경, 브레이스의 두께에 따른 핫스폿 응력의 차이점을 비교하였다. 또한 충전강관 N형 이음부에서 사재의 각도와 수직재와 사재사이의 거리를 변수로 하여 유한요소해석을 수행하였으며, 현재에 충전된 콘크리트의 강도의 변화에 따른 이음부의 핫스폿 응력 특성을 살펴보았다.

• 융합경영연구
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• 제5권2호
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• pp.10-32
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• 2017

The landscape of corporate reporting is changing quickly. The concepts, elements and principles that characterize the way organizations plan, manage and report their annual performances are currently being questioned, debated, and redesigned throughout the world. However, widening the scope of corporate performance and reporting is a major issue. Research needs to bridge the gap between social and financial performance by considering corporate performance in a wider perspective. At base, IR is a relatively new but powerful idea: enhancing the way organizations think, plan and report the story of their business. Organizations are using IR to communicate a clear, concise, integrated story that explains how all of their resources are creating value. This paper examines the rise of what has been widely claimed to represent a new and striking future for corporate reporting, namely the notion of "Integrated Reporting" (IR). Unfortunately, there is poor empirical research work undertaken which has focused on published integrated reports. This research study provides initial analysis of the content and structure of the corporate integrated reports published in 2013 and available on the International Integrated Reporting Council (IIRC) Emerging Examples Database. As part of this study, Integrated Reports were analyzed for company information, report information and report content. Moreover, they were also evaluated as to the extent these adhered to the integrated reporting (IR) Guiding Principles, Content Elements, and the multiple capitals model. Findings of this study indicate that "early integrated reports were mostly lengthy, fail to adhere to all the guiding principles, and covered four of the six capitals suggested." At present, no universally accepted global framework for IR exists and it is still largely a voluntary practice. We believe that IR of both financial and non-financial performance should be made mandatory, and it should become a universal practice for all the global listed companies within the next 5-10 years.

• Smart Structures and Systems
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• 제32권1호
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• pp.9-21
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• 2023

The parameters of civil engineering structures have time-variant characteristics during their service. When extremely large external excitations, such as earthquake excitation to buildings or overweight vehicles to bridges, apply to structures, sudden or gradual damage may be caused. It is crucially necessary to detect the occurrence time and severity of the damage. The unscented Kalman filter (UKF), as one efficient estimator, is usually used to conduct the recursive identification of parameters. However, the conventional UKF algorithm has a weak tracking ability for time-variant structural parameters. To improve the identification ability of time-variant parameters, an adaptive UKF with forgetting factor (AUKF-FF) algorithm, in which the state covariance, innovation covariance and cross covariance are updated simultaneously with the help of the forgetting factor, is proposed. To verify the effectiveness of the method, this paper conducted two case studies as follows: the identification of time-variant parameters of a simply supported bridge when the vehicle passing, and the model updating of a six-story concrete frame structure with field test during the Yangbi earthquake excitation in Yunnan Province, China. The comparison results of the numerical studies show that the proposed method is superior to the conventional UKF algorithm for the time-variant parameter identification in convergence speed, accuracy and adaptability to the sampling frequency. The field test studies demonstrate that the proposed method can provide suggestions for solving practical problems.

• 대한토목학회논문집
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• 제26권5A호
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• pp.823-832
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• 2006

PSC 합성거더교의 사용성을 만족시키기 위해서는 사용하중 상태에서 구조물에 발생하는 응력과 변형을 정확히 예측하는 것이 필수적이다. 응력과 변형은 콘크리트의 건조수축과 크리프, 그리고 긴장재의 리락세이션에 의한 영향으로 시간에 따라 연속적으로 변화된다. 시간의존적인 영향의 중요성은 전체 구조가 일시에 제작되는 경우보다 단계별로 시공되는 프리캐스트 프리스트레스트 콘크리트 구조물에서 더욱 커진다. 본 연구에서는 기존 30 m PSC거더 표준단면을 이용한 PSC 합성거더교에 대해 긴장력 도입시기와 콘크리트바닥판 타설시기의 변동성을 고려한 장기거동해석을 수행하였다. 단순교와 연속교에 대해 시공단계별 장기거동 해석을 위한 PSC 합성거더교 전용해석프로그램을 개발하였으며 이를 이용하여 변수해석을 수행하였다. 시공단계별 변수해석결과를 토대로 PSC 합성거더교의 장기거동특성과 현행 프리스트레스 감소량과 관련된 현행규정의 적용한계성을 분석하였다.

• 해양환경안전학회지
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• 제29권6호
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• pp.628-638
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• 2023

자율운항선박 기술은 점차 발전하고 있다. 하지만 완전 자율운항선박이 등장하기 전까지는 원격운영센터에서 원격운영자가 제어하는 형태를 가지게 될 것이다. 그러나 현재 그들의 면허체계는 국내외적으로 정해지지 않았다. 역량이 검증되지 않은 원격운영자의 등장은 항행 안전에 위험이 될 것이다. 본 논문에서는 문헌 연구를 통해 원격운영자의 면허체계를 위해 고려해야 할 평가기준과 국내 해기사 면허체계 내에서 수립할 수 있는 방안을 모색하고 AHP를 활용하여 분석하였다. 그 결과 원격운영자의 면허체계를 위해서는 우선적으로 법률제정이 필요하고 선박직원법 제4조 해기사 면허의 직종에 원격운영자의 직종을 추가하는 방안이 가장 선호되었다. 이에 따라 원격운영센터의 조직구성도 기존 선박의 선교인적관리 조직과 유사하게 형성할 수 있을 것이다. 본 연구는 자율운항선박의 인적 관리 측면에서 원격운영자의 효율적인 양성과 항행 안전에 이바지할 수 있을 것이다.