• 대한조선학회논문집
• /
• 제61권2호
• /
• pp.125-134
• /
• 2024

The Safe Operating Envelope (SOE) combined with Short-Take-Off and Vertical Landing (STOVL) performance is an essential consideration of a light aircraft carrier for design of hull shape with excellent seakeeping performance in terms of naval air operations as well as traditional naval ship missions such as Transit and Patrol (TAP), and Replenishment at Sea (RAS) and so on. A variety of procedures are systematically combined to determine SOE considering rather complicated missions associated with operation of aircraft onboard. The evaluation of take-off and landing safety missions onboard should consider wind effect on deck and severer seakeeping indices and standards compared with conventional naval ships. In order to support take-off and landing missions, various support activities of the crews are required. So, additional evaluation is needed for indicators such as MSI(Motion sickness Index) and MII(Motion Induced Interruptions), which are quantitative indicators of work ability that appear as a result of motion response. In this study, a standard procedure is developed including the seaworthiness performance indicators, standards, and evaluation procedures that should be considered during design of STOVL aircraft carrier. Analysis results are discussed in terns of air-wake on deck as well as seakeeping indices associated with design parameter changes in view of conceptual design of a light aircraft carrier.

• 한국경영과학회지
• /
• 제38권1호
• /
• pp.45-59
• /
• 2013

A long-term forecasting method for a new product in early stage of diffusion is proposed. The method includes a constrained non-linear least square estimation with the logistic diffusion model. The constraints would be critical market informations such as market potential, peak point, and take-off. Findings on 20 cases having almost full life cycle are that (i) combining any market information improves the forecasting accuracy, (ii) market potential is the most stable information, and (iii) peak point and take-off information have negative effect in case of overestimation.

• 대한기계학회논문집A
• /
• 제24권10호
• /
• pp.2646-2653
• /
• 2000

The performance of slider of a hard disk drive affects the durability of the system. Particularly, the flying ability of the slider is critical in terms of surface damage and head crash. In this work, the take-off characteristics of the slider for various types of laser zone textured bump geometries were investigated. Also, the effect of ambient pressure on the flying characteristics of the slider was experimentally observed. An index of air density which can be used as a parameter for evaluating the flying characteristic is introduced.

• Ocean Systems Engineering
• /
• 제7권2호
• /
• pp.89-106
• /
• 2017

The study explores a novel design of wave energy converter (WEC) that utilizes the interaction between an inside heaving vertical cylinder with an outside fixed hollow cylinder. This design originates from the oscillating water column (OWC) type WEC but replaces the pneumatic power take off (PTO) through the Wells turbine with the hydrodynamic PTO through the inside heaving cylinder. To effectively evaluate the maximum power output, the system has been modeled in the hydrodynamic software AQWA (developed by ANSYS Inc) that has accumulated extensive offshore industry users. Ranges of the PTO parameters have been examined to make sure that proper linear damping can be implemented to simulate the PTO force. Comparing the efficiency of the pneumatic PTO with the hydrodynamic PTO, it appears that the hydrodynamic PTO is more promising than the traditional Wells turbine for an OWC system.

• 공학교육연구
• /
• 제17권5호
• /
• pp.17-22
• /
• 2014

Unmanned aerial vehicles (UAVs) that have been recently commercialized can largely be divided into fixed-wing aircraft and rotor aircraft by their styles and flight characteristics. Although the fixed-wing aircraft represents higher power efficiency, higher speed, longer flight distance and larger loading weight than the rotor aircraft, they have a disadvantage of requiring a space for take-off and landing. On the other hand, the rotor aircraft can implement vertical take-off and landing (VTOL) and represents various flight modes (hovering, steep bank turns and low-speed flights). But they require both precision take-off control and attitude control. In this study, we used a quad-tilt rotor UAV to combine advantages in both the fixed-wing aircraft and the rotor aircraft. The quad-tilt rotor (QTR) system was designed and constructed by adding a tilt device with a servo motor to a general quad-rotor vehicle.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2021년도 가을 학술논문 발표대회
• /
• pp.232-233
• /
• 2021

As construction projects become larger and more complex in the construction environment, and as the Building Information Model(BIM) is technically introduced, the demand for construction costs in units of space is increasing. Cost estimating of spacial element can reduce the error in cost prediction method based on cost of work type and to utilize the construction cost data for each space in the design phase. The purpose of this study is to extract spatial statements by utilizing spacial information of quantitative statements based on items that are common elements of the Quantity Take-Off and Bill of Quantity.

• 국제학술발표논문집
• /
• The 5th International Conference on Construction Engineering and Project Management
• /
• pp.419-425
• /
• 2013

Recently AEC industry has required construction automation according to becoming large and complex. Thus BIM-based construction project is increased and used in whole fields of AEC industry. Quantity take-off and estimation fields are important factor for decision-making in conceptual and schematic design stages of construction projects. The purpose of this study improves reliability of the estimation through QTO based on Open BIM. Scope and method to apply QTO is to select conceptual design stage through LoD(Level of Detail) in AEC field and to extract information from BIM model through analysis of IFC structure. This study proceeds three step to make BIM model and check the model quality and calculate QTO. The methodology of QTO using IFC is to verify of result in this study and expects utilizing in design stage of construction projects. The result from this study is expected to decrease the risk factor and time of estimation in the project early phase through improving reliability of schematic estimation.

• 국제학술발표논문집
• /
• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
• /
• pp.7-11
• /
• 2011

Quantity take-off (QT) is one of the most important tasks for determining the total cost of a construction project, and it requires accuracy and reliability for the result. Accuracy and reliability in BIM-based QT are also required to assure the completeness of the result. However, there has been no basis to measure the completeness of the BIM-based QT result. As BIM is increasingly being adopted in the construction industry with a wide variety of purposes, it becomes more important to have a method to improve the completeness of BIM-based QT and criteria to measure it. This research focuses on the hypothesis that the completeness of BIM-based QT relies on the accuracy and reliability of BIM and the BIM-based QT process. As a basic research to determine the completeness of BIM-based QT, this research analyzes and derives factors that affect the completeness of BIM-based QT.

• Asia Marketing Journal
• /
• 제10권2호
• /
• pp.1-29
• /
• 2008

본 연구는 해외 여러 시장에서 제품을 판매하는 글로벌 기업의 입장에서 복수 시장에서 발생하는 제품 수준의 매출 이륙 시점을 예측할 수 있는 모형을 제시하였다. 이 모형을 이용하여 복수 시장 정보, 제품 속성 정보, 가격 정보, 매출 정보 중 매출 이륙 시점 예측에 유용한 설명 변수들을 규명하기 위해 국내 전자 업체가 2년 5개월간 10개국 시장에 판매한 90종류의 PDP TV, LCD TV들 월별 매출 자료들을 대상으로 실증 분석을 하였다. 분석 결과, 매출 이륙 시점 예측에 유용한 변수들을 다음과 같이 파악할 수 있었다. 첫째, 대상 제품이 표적 시장에 진출하기 이전에 진출한 타 시장에서의 매출 자료를 표적 시장에서의 대상 제품 매출 이륙 시점 예측에 이용하는 것이 가장 중요함을 실증 분석을 통해 알 수 있었다. 특히, 매출 이륙 시점 예측에 동일 제품의 타 시장 혁신 계수를 이용하는 것이 유용한 반면, 동일 제품의 타 시장 모방 계수는 예측력에 도움을 주지 못함을 알 수 있었다. 둘째, 타 제품의 표적 시장 확산 정보는 예상과 달리 대상 제품의 표적 시장에서의 매출 이륙 시점 예측에 기여하는 바는 낮음을 알 수 있었다. 셋째, 일반적 인식처럼 가격과 제품의 속성도 이륙시점의 발생 시기에 영향을 미치는 것을 알 수 있었다. 하지만 제품의 자체 가격 정보 보다 시장 평균 가격 대비 대상 제품 가격 비율이 매출 이륙 시점 예측에 보다 효과적임을 알 수 있었다. 마지막으로, 전기 누적 매출량 역시 PLC 중 초기 시점을 예측하는 상황임에도 불구하고 제품 수준의 매출 이륙 시점 예측에 중요한 변수임을 알 수 있었다. 본 연구에서 제시한 매출 이륙 시점 예측 모형은 평균치에 근거한 일반적 예측과 비교해 볼 때 높은 예측력을 보여 주었다. 본 연구에서 제시한 예측 모형을 이용할 경우 특히 예측 시점이 2기일 때 가장 높음을 알 수 있었다. 본 연구 결과가 기여하는 바를 보면 첫째, 기존 확산모형과 달리 본 연구에서는 제품의 매출 초기 시점인 매출 이륙 시점을 측정하고, 예측하는 모형을 제시하였다. 둘째, 본 연구는 글로벌 시장에서 적용 가능한 제품 수준의 매출 이륙 시점을 예측하였다. 셋째, 본 연구는 처음으로 매출 이륙 시점 예측력을 예측 시점 별로 분석하여 모형의 예측력을 이해하는 데 새로운 접근법을 제시하였다.

• 응용통계연구
• /
• 제24권6호
• /
• pp.1115-1128
• /
• 2011

절사표본 설계는 관심변수의 분포가 오른쪽으로 치우쳐진 경우에 모집단 일부를 표본조사에서 제외시켜 조사의 효율을 높이는 방법이다. 그러나 전체 모집단의 총합 추정을 위해서는 버려진 절사 층에 관한 추론이 필요하게 된다. 기존에 사용하고 있는 많은 방법들은 절사층에서 표본조사를 하지 않고 알려진 보조정보와 조사자료를 이용하여 절사층 총합을 추정하며 이를 이용하여 전체 모집단의 총합을 추정한다. 본 논문에서는 절사층을 완전히 표본 층에서 제거하지 않고 조사의 편리성 및 효율성을 고려하여 최소의 표본을 추출한 후 모집단 전체 총합을 추정하는 방법을 제안하였다. 또한 모의실험을 통하여 제안된 추정법과 기존 방법의 우수성을 비교하였다.