The planetary gearing system is compact and lightweight. The performance of planetary gearing system which uses floating intermediate rings have been found to be very good for practical systems. To apply this system for the reduction of rotation of an engine, in designing stage, the quantitative estimate of the load sharing factors is required for understanding the performance. The method widely used for this purpose is to make use of elastic deformation of components of the structure or to utilize hydrodynamic oil film. This paper shows the way how to analyze the static load sharing factors by using the coefficient ''. This method can be applied for non-linear systems such as oil film bearing. The influences of various factors on '' of oil film spring are also shown. Furthermore, It is established in this study that the use of floating intermediate ring in designing the planetary gearing system has a very high reliability.

국가 신재생에너지개발 장려정책으로 농업용저수지 내 수상태양광 발전시설 설치가 확대되고 있음에도 불구하고, 수상태양광 발전시설 설치가 수생태계에 미치는 영향을 판 단할 수 있는 장기적인 조사나 과학적 연구가 부족한 실정 이다(노 등, 2015). 일반적으로 수상 태양광 발전시설 설치 지역은 수온, 증발량 등의 물리적 환경변화가 국지적으로 발생하기 때문에(노 등, 2014; Melvin, 2015; Sahu, 2016), 미소생태계(microecosystem)가 형성되어 수생생물의 분포 및 군집특성의 변화로 이어진다. 따라서 수상태양광 설치지 역과 설치가 되지 않은 지역 간 어류군집 특성을 비교함으 로서 수상태양광 설치가 수생태계에 미치고 있는 영향을 간접적으로 유추할 수 있다. 특히, 수생태계의 영양단계 (trophic level)에서 상위단계에 해당하는 어류의 군집 특성 및 분포는 미소생태계의 형성유무와 형성된 미소생태계의 영양구조를 설명할 수 있는 근거가 된다. 수상태양광이 설치되어 있는 2개의 저수지는 실험군으로 하였고, 기후, 수상태양광 규모(전력생산량), 저수지 규모, 유역특성이 비슷한 인근의 저수지 1개소는 대조군으로 선 정하였다. 조사지점은 수상태양광 설치지역으로부터 일정 거리별(200~250m)로 6지점(수상태양광 발전시설 설치지 점을 기점으로 1~6번으로 지점번호 부여)을 선정하였으며, 지점별로 12절 자망(50m)을 설치한 후 24시간이 경과된 시점에서 어류를 채집하여 동정하였다. 장마기간 전·후로 총 2회의 어류조사를 실시하였으며, 현장조사 결과를 토대 로 종다양도를 산출하고 지점 간 유사도를 살펴보기 위해서 군집분석을 실시하였다. 현장 조사결과, 실험군인 A저수지는 총 8종 129개체가 채집되었으며, 블루길이 전체 개체수의 78.3%로 우점하였 다. 상대적으로 수변지역과 가까운 2번과 6번 지점이 각 5종, 7종으로 종수가 많았으며, 수상태양광 발전시설이 설 치된 지역과 가장 인접한 1번 지점에서는 타 조사지점에서 도 공통적으로 관찰되는 2종(백조어, 블루길)이 유사한 개 체수로 관찰되었다. 군집의 유사도 역시 1, 3번 지점과 4, 5번 지점, 그리고 2번, 6번 지점으로 그룹화되어, 수상태양 광 발전시설 설치지역으로부터 이격거리별로 종다양도 변 화는 없는 것으로 나타났다. 실험군인 B저수지는 총 3종만 이 관찰되어 어류 군집특성을 파악하기에 어려움이 있었다. 대조군인 C저수지는 총 11종 950개체가 채집되었으며, 치 리와 모래무지가 전체 종조성의 83.2%를 차지하였다. 출현 종수가 6~7종으로 조사지점별로 종조성이 유사하였으며, 군집분석 결과 역시 1, 3, 4번 지점과 2, 6번, 5번 지점으로 그룹화되어 특별한 경향성을 보이지 않았다. 본 연구결과로부터 수상태양광 발전시설 설치로 인한 물 리적 환경변화는 어류 군집특성의 변화를 유도할 만큼 크지 않다는 것을 알 수 있다. 실제 실험군에 설치된 수상태양광 발전시설은 수면과 접촉되지 않고 일정한 높이로 이격되어 있고, 태양광 패널을 지지하는 부력체 역시 수평적인 물순 환을 저해하지 않아 인근 수체와 연속적인 생태계로 볼 수 있다. 다만 본 연구의 조사방법이 수상태양광 발전시설 설 치지역과 그렇지 않은 지역의 어류군집 특성을 구분할 만큼 정밀도가 높지 않았다는 연구의 한계가 있을 수 있다. 따라 서 태양광 발전설비에 의한 수생태계 영향 규명을 위해서는 저수지 전체를 대상으로 수상태양광 발전시설 설치로 인한 에너지유입량, 1차 생산량 변화, 수생태계 영양구조 및 먹이 그물 변화 등에 대한 시스템적 연구가 함께 이루어져야 할 것으로 판단된다.

Unidirectionally solidified TiAl alloys were prepared by optically-heated floating zone method at growth rates of 10 to 70 mm/h in flowing argon. The microstructures and tensile properties of these crystal bars were found to depend strongly on the growth rate and alloy composition. TiAl alloys with composition of 47 and 50 at.%Al grown under the condition of 10 mm/h showed Ti3Al(α2)/TiAl(γ) layer structures similar to single crystals. As the growth rate increased, the alloys with 47 and 50 at.%Al compositions showed columnar-grain structures. However, the alloys fabricated under the condition of 10 mm/ h had a layered structure, but the alloy with increased growth rate consisted of γ single phase grains. The alloy with a 53 at.%Al composition showed a γ single phase regardless of the growth rate. Room-temperature tensile tests of these alloys revealed that the columnar-grained material consisting of the layered structure showed a tensile ductility of larger than 4 % and relatively high strength. The high strength is caused by stress concentration at the grain boundaries; this enhances the secondary slip or deformation twinning across the layered structure in the vicinity of the grain boundaries, resulting in the appreciable ductility.

Ocean economy plays a crucial role in the strengthening maritime safety industry and in the welfare of human beings. Electric Submersible Pumps (ESP) have been widely used in floating platforms on the sea to provide oil for machines. However, the ESP fault may lead to ocean environment pollution, on the other hand, a timely fault diagnosis of ESP can improve the ocean economy. In order to meet the strict regulations of the ocean economy and environmental protection, the fault diagnosis of ESP system has become more and more popular in many countries. The vibration mechanical models of typical faults have been able to successfully diagnose the faults of ESP. And different types of sensors are used to monitor the vibration signal for the signal analysis and fault diagnosis in the ESP system. Meanwhile, physical sensors would increase the fault diagnosis challenge. Nowadays, the method of neural network for the fault diagnosis of ESP has been applied widely, which can diagnose the fault of an electric pump accurately based on the large database. To reduce the number of sensors and to avoid the large database, in this paper, algorithms are designed based on feature extraction to diagnose the fault of the ESP system. Simulation results show that the algorithms can achieve the prospective objectives superbly.

원유나 벙커C유와 같은 지속성 기름이 해상에 유출되면 풍화과정을 거쳐 점도가 높아지고, 부유 쓰레기와 섞이게 되면 이를 수거할 수 있는 장비는 매우 제한적이다. 본 연구에서는 기존 유회수기의 외부에 위치한 부속장치들을 본체 내부로 배치하고, 컨베이어 벨트와 강제유입장치인 스위퍼 및 부력체를 탑재한 수집조로 구성하여 자항과 리모트컨트롤이 가능한 무인 컨베이어 벨트식 부유쓰레기 및 고점도유 회수장비를 개발하였다. 실해역 테스트에서 30 m의 거리를 1.2 knots의 속도로 자항하며, 전 후, 좌 우에서 안정적인 균형유지와 구동부의 정상작동을 확인하였다. 임시저장조를 이용한 유회수 성능테스트 결과, 최소 7.8 ㎘/h에서 최대 23.3 ㎘/h까지 유출유 회수가 가능하였다. 또한, 페트병 등 부유쓰레기와 유출된 기름이 혼합된 조파수조에서 실시한 회수량 측정 테스트 결과는 7.7 ㎘/h로 나타났다. 본 연구를 통해 개발된 장비가 해상기름오염사고 시 현장에 신속하게 투입된다면 방제능력 향상에 기여할 수 있을 것으로 기대하며, 현재 운용중인 Portable 유회수기의 성능개선 연구에 활용될 수 있을 것으로 판단된다.

Floating PV generation system, renewable energy power plant, is able to overcome the disadvantages of ground PV generation system and improve generating efficiency. The frame structural system is an established technology among a diversity of structural technologies which has been developed for related fields. In this paper, the both structural safety and characteristics of floating PV generation structures depend on the different placement angle of solar module are investigated to improve the commercial viability, the structural safety, and characteristics of floating PV generation structures. In addition, for the estimation of structural safety, FE analyses are conducted. From the results, the lower placement angle of solar module improves the structural safety of floating PV generation system.

This study presents the behavioral characteristics of submerged floating tunnels under harsh environmental conditions. To evaluate the dynamic characteristics of the submerged floating tube moored by tethers, hydrodynamic analysis was performed in time-domain. To consider the irregular wave loading condition, JONSWAP wave spectrum was used with specific significant wave height and peak period. For applying the irregular wave in the explicit dynamic analysis procedure, equivalent regular wave components which have same wave energy were applied to the external force term with random phases. According to this study, lateral and vertical motion can be effectively controlled by adjusting initial tether angle and draft. Evaluation of fatigue damage of mooring lines can be conducted by analyzing the dynamic structural stresses with appropriate S-N curves and stress concentration factors. This study also dealt with short-term fatigue analysis for checking the tethers. According to this study, cumulative fatigue damage of the tethers is definitely affected by the essential design factors such as design draft of the tunnel and tether arrangement.

Shim, Jae Hyung. 2017. “The Relationship between a Linguistic Landscape and a Floating Population: The Case of the Greater Anyang Region”. The Sociolinguistic Journal of Korea 25(1). 85~117. The purpose of this paper is to look at a relationship between urban planning in Korean cities and linguistic landscapes. The study attempts to see the effect of urban development on the rate of English use in the public sphere, and how different sizes of a floating population affect such differences. In doing so, the Greater Anyang Region, located south of Seoul, was selected as the site for the current study. This area is comprised of three cities (Anyang, Gunpo, Uiwang) with a number of business districts including the old downtown and new centers of each city, creating a clear difference in landscape between each area. The study observed the linguistic landscape around subway stations in this region. By observing the rate of English use on commercial signs in these commercial districts, it was found that there is a parallel line between the size of a floating population and the percentage of English in the public sphere. In addition, different rates of English use in different areas reflect a decline of old downtowns, while showing the higher economic status of newer commercial districts. Such phenomena provide an instance of a close relationship between the use of English and a floating population, since the busier business districts appear to have more use of English.

In this paper, a study on noise reduction characteristics of the precast floating track system, being developed as measures to mitigate noise and vibration of existing as well as constructing elevated railroad stations, is presented using numerical analysis. One of the most prominent sound analysis program, Virtual Lab., is utilized in investigating noise reduction performance of the precast floating track system, and structural velocity data, obtained from vibration analysis on a model-updated elevated railroad station considering vehicle-track-structure interaction, are used for the input of the sound analysis. The sound analysis is performed using the finite element method, and noise reduction performance before and after installing the precast floating track system is compared at three enclosed areas in the Daecheon Station, selected as a representative of elevated railroad stations in this nation. From the comparison result, it is seen that the precast floating track system can decrease noise by average of 5dB∼8dB when the Saemaeul train passing through the station and 10dB∼15dB when the KTX train passing through. Also, the noise reduction characteristics is different depending on the type of train and the distance from the track.

This paper is concerned with the numerical analysis of dynamic response of floating offshore wind turbine subject to underwater explosion using an effective non-reflecting technique. An infinite sea water domain was truncated into a finite domain, and the non-reflecting technique called the perfectly matched layer(PML) was applied to the boundary of truncated finite domain to absorb the inherent reflection of out-going impact wave at the boundary. The generalized transport equations that govern the inviscid compressible water flow was split into three PML equations by introducing the direction-wise absorption coefficients and state variables. The fluid-structure interaction problem that is composed of the wind turbine and the sea water flow was solved by the iterative coupled Eulerian FVM and Largangian FEM. And, the explosion-induced hydrodynamic pressure was calculated by JWL(Jones-Wilkins-Lee) equation of state. Through the numerical experiment, the hydrodynamic pressure and the structural dynamic response were investigated. It has been confirmed that the case using PML technique provides more reliable numerical results than the case without using PML technique.

Microlensing is generally thought to probe planetary systems only out to a few Einstein radii. Microlensing events generated by bound planets beyond about 10 Einstein radii generally do not yield any trace of their hosts, and so would be classified as free floating planets (FFPs). I show that it is already possible, using adaptive optics (AO), to constrain the presence of potential hosts to FFP candidates at separations comparable to the Oort Cloud. With next-generation telescopes, planets at Kuiper-Belt separations can be probed. Next generation telescopes will also permit routine vetting for all FFP candidates, simply by obtaining second epochs 4--8 years after the event.At present, the search for such hosts is restricted to within the ``confusion limit'' of θconfus ∼ 0.25 〃, but future WFIRST (Wide Field Infrared Survey Telescope) observations will allow one to probe beyond this confusion limit as well.

본 연구에서는 부유구조물 모델링의 효율성 및 응답의 정확성을 분석하기 위해 유체 영역을 압력으로 정의한 유탄성 해석법에 1차원 보-2차원 유체 결합의 1차원 문제와 2차원 판-3차원 유체 결합의 2차원 문제를 적용하여 수치해석을 수행하였다. 그리고 1차원 문제와 2차원 문제의 모델링 차원에 따른 응답을 비교하기 위해 다양한 평판의 변장비와 입사파의 조건을 적용하였다. 이에 따르면 강체거동의 영향이 큰 장주기파에서는 변장비가 변하더라도 두 문제의 유탄성 응답이 거의 유사하게 나타나지만 탄성거동의 영향이 지배적인 단주기파에서는 모델링 차원에 따라 뚜렷한 차이가 발생한다. 즉, 1차원 보 모델은 비록 입사파의 각도는 고려할 수 없지만 평판의 변장비가 클 경우에 유탄성 해석에 적용이 가능하다. 또한, 2차원 평판보다 단순화된 모델링 조건으로서 부유구조물의 전반적인 응답을 분석할 수 있을 뿐만 아니라 수치해석의 효율을 높일 수 있다.