전 세계적으로 환경오염 문제로 국제해사기구인 IMO(International Maritime Organization)에서는 이산화탄소 배출량과 관련된 지수인 EEDI(Energy Efficiency Design Index)를 만들어 새로 건조되는 선박들에 대한 규제를 적용하고 있다. 본 연구에서는 158k 원유운반선의 선형과 프로펠러 후류를 분석하여 새로운 형태의 에너지 저감 장치인 ring stator를 제안하였다. 최근의 선박들은 반류가 적은 즉 선미부 유속이 빠른 경향으로 발전되고 있어 덕트가 포함된 ESD(Energy Saving Device)는 저속비대선이라도 컨테이너선처럼 적용하기가 어렵다. 본 연구에서 제안한 ring stator는 이러한 점을 고려하여 새로이 개발된 장치로써 자항 성능 향상 뿐 아니라 저항 성능의 최소화를 목표로 설계를 진행하였다. Star-CCM+의 상용 프로그램을 활용하여 CFD 해석을 통해 설계한 ring stator의 성능을 확인하였고 최종 제시한 설계안에 대해 약 3.4 %의 추진 효율 개선 효과가 있음을 확인하였다. 설계된 ring stator에 대한 실험과의 비교 등을 통해 성능 검증 및 보다 정도 높은 최적화에 대한 연구를 추후 수행할 계획이다.

The Ozone Dynamics Investigation Nano-Satellite (ODIN) is a CubeSat design proposed by Chungnam National University as contribution to the CubeSat Competition 2019 sponsored by the Korean Aerospace Research Institute (KARI). The main objectives of ODIN are (1) to observe the polar ozone column density (latitude range of 60 to 80 in both hemispheres) and (2) to investigate the chemical dynamics between stratospheric ozone and ozone depleting substances (ODSs) through spectroscopy of the terrestrial atmosphere. For the operation of ODIN, a highly ecient power system designed for the specic orbit is required. We present the conceptual structural design of ODIN and an analysis of power generation in a sun synchronous orbit (SSO) using two dierent congurations of 3U solar panels (a deployed model and a non-deployed model). The deployed solar panel model generates 189.7 W through one day which consists of 14 orbit cycles, while the non-deployed solar panel model generates 152.6 W. Both models generate enough power for ODIN and the calculation suggests that the deployed solar panel model can generate slightly more power than the non-deployed solar panel model in a single orbit cycle. We eventually selected the non-deployed solar panel model for our design because of its robustness against vibration during the launch sequence and the capability of stable power generation through a whole day cycle.

The domestic of modern architectural remodeling method emphasizes simple aesthetic elements, and the correct design and construction methods are not established based on quantitative grounds, thus damaging the value of cultural properties. This study attempts to re-examine the value of modern buildings recognized as old buildings. It is a basic step to present the correct remodeling of the building. The design criteria for exterior wall remodeling of modern buildings were presented. These research results are suitable for energy conservation design standards and can prevent defects in buildings. In the future, more accurate analysis will be required by securing physical property values for various domestic materials through subsequent research.

In recent years, importance of blockchain systems has been grown after success of bitcoin. Distributed consensus algorithm is used to achieve an agreement, which means the same information is recorded in all nodes participating in blockchain network. Various algorithms were suggested to resolve blockchain trilemma, which refers conflict between decentralization, scalability, security. An algorithm based on Byzantine Agreement among Decentralized Agents (BADA) were designed for the same manner, and it used limited committee that enables an efficient consensus among considerable number of nodes. In addition, election of committee based on Proof-of-Nonce guarantees decentralization and security. In spite of such prominence, application of BADA in actual blockchain system requires further researches about performance and essential features affecting on the performance. However, performance assessment committed in real systems takes a long time and costs a great deal of budget. Based on this motivation, we designed and implemented a simulator for measuring performance of BADA. Specifically, we defined a simulation framework including three components named simulator Command Line Interface, transaction generator, BADA nodes. Furthermore, we carried out response surface analysis for revealing latent relationship between performance measure and design parameters. By using obtained response surface models, we could find an optimal configuration of design parameters for achieving a given desirable performance level.

In this study, a field bridge test was conducted to find the dynamic properties of cable supported bridges with resilient-friction base isolation systems (R-FBI). Various ambient vibration tests were performed to estimate dynamic properties of a test bridge using trucks in a non-transportation state before opening of the bridge and by ordinary traffic loadings about one year later after opening of the bridge. The dynamic properties found from the results of the tests were compared with an analysis model. From the result of the ambient vibration tests of the cable supported bridge with R-FBI, it was confirmed that the dynamic properties were sensitive to the stiffness of the R-FBI in the bridge, and the seismic analysis model of the test bridge using the effective stiffness of the R-FBI was insufficient for reflecting the dynamic behavior of the bridge. In the case of cable supported bridges, the seismic design must follow the “Korean Highway Bridge Design Code (Limit State Design) for Cable supported bridges.” Therefore, in order to reflect the actual behavior characteristics of the R-FBI installed on cable-supported bridges, an improved seismic design procedure should be proposed.

In the automotive industry, the platinum titanium anodes (Pt/Ti anode) play a significant role in electroplating of chromium coating on the vehicle’s shock absorber piston rod. In this paper, the structure of Pt/Ti anode was designed to obtain high quality and save time for the electroplating process. The structure of anode was designed in 2D & 3D modeling and analyzed by CATIA and ABAQUS program, respectively. The structural modeling of the anode was analyzed and carried out using a finite element method (FEM) by applied various loads. The manufacture anodes were installed in an electroplating bath in order to test the efficiency of chromium coating on shock absorber piston rod and safety of anode structure. The results presented indicate that the structural analysis is safe after applied loads due to the allowable stress is higher than the maximum equivalent stress about 4 times, and the chromium coating test obtained high-efficiency results.

식물사회네트워크란 식물사회를 이해하기 위한 기존의 식물사회학적 방법과 사회과학에서 최근에 주목받고 있는 사회연결 망 분석 방법을 접목하여 식물사회연결망을 시각화하고 분석하는 것을 말한다. 구축 및 분석 과정은 조사구 설정 및 출현 수종 조사, 종간결합분석, 소시오그램 작성, 네트워크 구조 및 중심성 분석 순으로 진행된다. 식물사회네트워크를 구축하기 위해 본 연구는 해안식생과 내륙식생을 동시에 볼 수 있는 부산광역시를 중심으로 다양한 상관우점식생이 포함되도록 708개 조사구를 설치하여 출현 수종을 조사하였다. 조사 결과, 출현한 수종은 모두 195종이었으며, 상록수 42종, 낙엽수 151종, 반상록수 2종으로 나탔으며, 전체 출현수종을 중심으로 종간결합분석을 실시하였다. 종간결합 분석 결과, 친화종수는 사스레피 나무(47종), 마삭줄(46종), 감태나무(44종), 팥배나무(44종), 광나무(41종) 순으로 나타났으며, 이를 바탕으로 gephi 0.9.2. program을 활용하여 소시오그램을 작성하였다. 작성된 소시오그램은 해안에서 주로 출현하는 그룹과 그렇지 않은 그룹으로 나뉘어져 있어 부산광역시 산림식생의 지리적 분포특성을 반영하고 있었다. 네트워크 구조를 분석한 결과, 1,709개의 연결선 (link)이 나타났고, 한 수종과 종간결합을 갖는 종수의 평균은 약 17.5개였다. 밀도는 0.09, 지름은 5, 평균 경로거리는 2.268로 분석되었는데, 사회과학분야의 네트워크 특성과 정밀한 비교 분석을 위해 앞으로 다양한 식물사회네트워크 구축이 진행되어야 할 것으로 판단되었다. 부산광역시 식물사회네트워크에서는 사스레피나무, 감태나무, 광나무, 마삭줄 등이 중심성 이 높은 것으로 나타났다.

In this study, the design of anchorage zone for unbonded post-tensioned concrete beam with single tendons of ultimate strength 2400MPa was evaluated to verify that the KDS 14 20 60(2016) and KHBDC 2010 codes are applicable. The experimental results showed that the bursting force equation of current design codes underestimated bursting stress measured by test, because the KDS 14 20 60(2016) and KHBDC 2010 propose the location of the maximum bursting force 0.5h which is the half of the height of member regardless of stress contribution. Although the allowable bearing force calculated by current design codes was not satisfied the prestressing force, the cracks and failure in anchorage zone was not observed due to the strengthening effect of anchorage zone reinforcement.

The purpose of this study is to provide the priority of the front-loading factors in the design stage of the automotive parts development process in order to efficiently and effectively respond to the demands of the car maker (customer). Front-loading is defined as a strategy in order to improve development performance by shifting the identification and solving of design problems to earlier phases of a product development process. Two approaches of the front-loading are project-to-project knowledge transfer and rapid problem solving. For the study, a survey was conducted on the R&D department in the automobile parts company and analyzed by AHP (Analytic Hierarchy Process) method. The result of the survey shows the cost savings is the highest weight in terms of front-loading effect and in terms of front-loading factors, it gives priorities as “the problems of past project” first, “Design Review” second, “CAE (Computer Aided Engineering)” third, “FMEA (Failure Mode and Effects Analysis)” fourth, “benchmarking” and SR (Sourcing of Requirements). The results of the study will be helpful to provide practical value for improving product design of component development.