• 한국해양공학회지
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• 제35권5호
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• pp.360-368
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• 2021

The need for energy harvesting in marine environments is gradually increasing owing to the energy limitation of marine robots. To address this problem, a catamaran-type sail drone (CSD), which can harvest marine energies such as wind and solar, was proposed in a previous study. However, it was designed and manufactured without considering the stability, optimal hull-form, and maintenance. To resolve these problems, a CSD with two keels, a performance estimator, V-shape hulls, and modularized components is proposed and its mechanism is developed in this study. To verify the performance of the CSD, the performance estimation using smoothed-particle hydrodynamics (SPH) and the heading control using fuzzy logic controller (FLC) are performed. Simulation results show the attitude stability of the CSD and the experimental results show the straight path of the CSD according to wind conditions. Therefore, the CSD has potential applications as an energy harvesting system.

• Advances in concrete construction
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• 제7권4호
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• pp.277-288
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• 2019

The formulation of self-compacting concretes (SCC) and the study of their properties at the laboratory level were currently well mastered. The aim of this work is to characterize SCC under hot climatic conditions and their effects on the properties of fresh and hardened SCC. Particularly, the effect of the initial wet curing time on the mechanical behavior such as the compressive strength and the durability of the SCCs (acid and sulfate attack) as well as the microstructure of SCCs mixtures. In this study, we used two types of cement, Portland cement and slag cement, three water/binder (W/B) ratio (0.32, 0.38 and 0.44) and five curing modes. The obtained results shows that the compressive strength is strongly influenced by the curing methods, 7-days of curing in the water and then followed by a maturing in a hot climate was the optimal duration for the development of a better compressive strength, regardless of the type of binder and the W/B ratio.

• Journal of the Korean Wood Science and Technology
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• 제49권6호
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• pp.566-573
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• 2021

We investigated color changes on the outer surfaces of Phyllostachys bambusoides bam-boo by heat treatment under three different temperatures (180℃, 200℃, and 220℃) for three different durations (60 min, 90 min, and 120 min). A method of predicting the bam-boo surface color change after heat treatment was developed to provide valuable information and increase the added value of domestic bamboo products. The three average color parameters L^*, a^*, and b^* decreased, and the overall color changes increased as the severity factor increased. The values of L^* × a^* × b^* were highly related to the severity factor, and the optimal duration time for the desired bamboo surface color with a certain heat-treatment temperature could be estimated.

• 한국항해항만학회지
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• 제43권5호
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• pp.273-280
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• 2019

This study developed an optimization model, defined as the IPS (Itinerary for Passenger Satisfaction), for a cruise ship to identify an itinerary that maximizes passenger satisfaction. A 0-1 integer programming model was developed to provide an optimal sequence of ports of call, assigning a destination to each day of the cruise. The concepts of the destination access network and the neighborhood of a destination were designed and manipulated to organize the complex network of destinations so that each next destination is selected within a practical overnight sail. The developed model can also be viewed as a reduced variant of the traveling salesperson problem with less constraints. A set of example tests shows that practical scenarios of the IPS with moderate cruise duration can be easily solved with light computation loads. Considering cruise ship passengers usually make their decisions not relying on only one destination but on an itinerary in its entirety, the purpose of this study was to identify itinerary alternatives to attract potential cruise passengers for attaining maximum occupancy level.

• 한국정보기술학회 영문논문지
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• 제10권2호
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• pp.33-48
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• 2020

By Digital Transformation, new technologies like ML (Machine Learning), Big Data, Cloud, VR/AR are being used to video streaming technology. We choose ML to provide optimal QoE (Quality of Experience) in various network conditions. In other words, ML helps DASH in providing non-stopping video streaming. In DASH, the source video is segmented into short duration chunks of 2-10 seconds, each of which is encoded at several different bitrate levels and resolutions. We built and compared the performances of five prototypes after applying five different machine learning algorithms to DASH. The prototype consists of a dash.js, a video processing server, web servers, data sets, and five machine learning models.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.21-22
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• 2023

In reinforced concrete constructions, reinforcing bar generates more CO₂ per unit weight than other construction materials. In particular, cutting and bending rebar is the main source of rebar waste in the construction industry. Rebar-cutting waste is inevitable during the construction of a reinforced concrete structure since the rebar is not manufactured as designed. Large amounts of waste can be avoided by utilizing optimal cutting patterns and schedules. This research provides a fundamental analysis of the automatic calculation of column rebar length using BIM-based shape codes to minimize cutting waste to near zero. By employing this approach in practice, it is possible to minimize the rate of rebar-cutting waste, reduce costs, shorten construction duration, and reduce CO₂ emissions. In addition, the development of this research will serve as a clue for the development of BIM-based rebar layout automation algorithms.

• Journal of Digestive Cancer Research
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• 제2권2호
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• pp.52-55
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• 2014

The incidence of colorectal cancer (CRC) has continuously increased and CRC is a major cause of cancer-related death. Systemic chemotherapy has resulted in a significant improvement in overall survival in metastatic CRC. The development of biologic agents for the treatment of CRC has additionally expanded the options for the treatment. Cetuximab is useful in KRAS wild type tumors in combination with chemotherapy for metastatic disease in both the first and second line settings. It is also used as monotherapy after failure of both irinotecan and oxaliplatin containing regimens. Panitumumab has similar indications, and is primarily used in patients intolerant to cetuximab due to hypersensitivity reactions. Bevacizumab is primarily used as first line and second line therapy in metastatic CRC. However, the optimal way and duration to combine these chemotherapeutic agents are not yet established.

• 한국건설관리학회논문집
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• 제20권4호
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• pp.56-68
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• 2019

거푸집 공사는 전체 건축공사의 공사기간 및 공사비 측면에서 상당 부분을 차지하고 있으며, 구조물공사의 품질, 마감 및 설비 등 후속공사에도 직접적인 영향을 미치는 매우 중요한 공정이다. 그러나 국내 건설현장에서의 거푸집 공법선정은 객관적인 데이터를 바탕으로 하지 않고, 현장 실무자의 경험과 직관에 의존하여 이루어지는 경우가 대부분이다. 그 결과, 다수의 현장에서 공기단축, 비용절감 등의 효과가 큰 신공법을 적용하고자 할 경우, 객관적이고 합리적인 의사결정 절차의 부재로 인해 최적 공법선정 시 어려움을 겪을 뿐만 아니라, 현장의 특성을 고려하지 못한 의사결정으로 인해 공기지연, 비용증대 등의 문제가 발생하고 있는 실정이다. 이러한 문제를 해결하기 위해 거푸집 공법선정과 관련한 다양한 선행연구가 이루어졌으나 현장조건이라는 중요한 요인을 고려하지 못해 실제 현장에서 적용하여 활용하기에 다소 한계성이 있었다. 따라서 본 연구는 현장 유형별 조건을 고려한 정량적 거푸집 선정 의사결정 지원 모델 개발을 그 최종 목적으로 한다. 개발된 의사결정 지원 모델은 공사현장에서 거푸집 선정 의사결정시 정량적인 평가 데이터를 제공함으로써, 기존의 경험에 의존하여 결정하던 의사결정 방법보다 신속하고 객관적으로 최적의 거푸집 공사를 선정 할 수 있도록 도울 것으로 사료된다. 또한, 경험이 풍부하지 않은 엔지니어도 본 연구의 의사결정 지원모델을 활용하여 현장의 조건을 고려한 보다 객관적이고 합리적인 의사결정을 내릴 수 있을 것으로 기대된다.

• 한국수자원학회논문집
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• 제55권10호
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• pp.775-784
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• 2022

본 연구에서는 임의지속기간의 확률강우량 산정을 위해 실무에서 주로 사용되고 있는 전대수 다항식형 확률강우강도식의 최적차수 결정을 위하여 경상북도 내 9개 지점을 대상으로 확률강우량을 산정하고 전대수 다항식형 강우강도식의 회귀계수를 추정하였다. 추정된 지점별 다항식을 대상으로 단계선택법을 이용하여 각 지점별 다항식의 최적변수를 선정하고 선정된 변수들의 통계적 유의성을 검토하기 위하여 분산분석을 통한 유의성 검정을 실시하였으며, 이들 결과를 이용하여 각 지점별 통계적으로 적절하게 산정된 강우강도식을 제시하였다. 경북 9개 지점의 전대수 다항식형 강우강도식의 변수선정 결과는 6개 지점에서 1~3차식이 최적식으로 나타났고 1개 지점이 불완전 3차식이 최적식으로 나타났다. 그 중 1차는 Sherman 식, 2차는 General 식의 형태와 유사하므로 독립변수의 수를 증가시켜 적합도를 높이고 사용 편의를 위해 통일된 형태의 강우강도식으로 제시한다면 전대수 다항식형 강우강도식은 3차 회귀식까지만 고려하여도 통계학적으로 문제가 없는 것으로 판단된다.

• 농업과학연구
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• 제43권1호
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• pp.28-32
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• 2016

This experiment was carried out to determine optimal culture conditions for the production of cut flowers and tubers of Calla (Zantedeschia 'Black Magic') in highlands. To achieve the research purpose, growth of 'Black Magic' Calla influenced by tuber hardness (3.3 and $6.0kg/cm^2$), $GA_3$ concentration (0, 100 and $200mgL^{-1}$), duration of $GA_3$ treatment (24 hr, 12 hr and 30min before planting) were investigated. When tubers have high hardness, those were not severely injured by soft rot disease regardless of $GA_3$ concentrations and treatment durations. Tubers with low tuber hardness showed more than 90% of soft rot occurrence when treated with $200mgL^{-1}$ $GA_3$ for 24 hrs before planting. However, soft rot did not occur when tubers were treated with $200mgL^{-1}$ $GA_3$ for 12 hrs before planting. In conclusion, $GA_3$ treatment results showed soft rot occurrence statistically significant degree in accordance with the bulbs hardness. In addition, the yield of the cut flowers is the result received the greatest effect in accordance with the bulbs in size and appeared to not be determined in accordance with the $GA_3$ treatment concentration and hardness bulbs. To obtain flowers without soft rot symptom, tubers (as $6.0kg/cm^2$) should be completely dried after $GA_3$ treatment.