• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.7-12
• /
• 2008

A hot stamping technology of vehicle door impact beam made of thin sheet steel has been developed, with the aim of ensuring occupant safety in a side collision. This technology has been implemented to increase the strength of vehicle body parts and to reduce not only the weight of door impact beam but also the number of work processes. Mechanical tests were performed to obtain material properties of hot-stamped specimen and those were used as input data in stamping and structural simulation for optimal design of door impact beam. Strength of hot-stamped door impact beam increased to the value 102% higher than that of conventional pipe-shaped door impact beam and structural simulation showed that hot-stamped door impact beam achieved 28% weight reduction.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.929-933
• /
• 2004

A robot manipulator is usually operated in two modes: free motion and constraint motion according to the fact whether the robot comes into contact with the environment or not. At the moment of contact, impact occurs, and sometimes, it can possibly degrade the robot's performance such as vibration and at worst, shortens its lifetime. In this article, a new proposed algorithm is described by introducing a command signal modification method on the basis of impedance control and a validity of the proposed algorithm is demonstrated by showing the simulation study.

• The Bulletin of The Korean Astronomical Society
• /
• v.36 no.1
• /
• pp.41.2-41.2
• /
• 2011

P/2010 A2, a main-belt asteroid having comet-like dust trail was discovered in January 2010, but the origin of the trail is controversial. Moreno et al. (2010) reported water-ice sublimation as a mechanism for the comet-like activity, whereas other researches (Jewitt et al. 2010; Snodgrass et al. 2010) stated that impact collision contributed to the dust trail. For asteroids are categorized based on spectral shape, optical observation using different color filters makes it possible to determine the taxonomic type of P/2010 A2 nucleus, thus gives an answer to the question of activation mechanism of the object. In this presentation, we report multiband observation of P/2010 A2 in January and March 2010 with 1-meter telescope of Ishigaki-Jima Astronomical Observatory. We employed three broadband filters of g', Rc, and Ic. In this presentation, we focus on the data acquisition, the reduction and the derivation of the reflectance spectrum of debris in the trail. Finally we discuss the potential cause of dust ejection from this asteroid.

• Annual Conference of KIPS
• /
• 2015.10a
• /
• pp.390-392
• /
• 2015

IEEE 802.11 DCF(Distributed Coordination Function) 프로토콜은 이진 지수 백오프 방식을 사용한다. 단말은 데이터 전송 전에 충돌을 피하기 위해 일정한 시간동안 채널 휴지(Idle)를 기다린다. 데이터 전송이 성공하면 경쟁 윈도우 값을 두 배로 증가시키고 실패하면 최소 값으로 초기화 한다. 이를 통해 DCF는 충돌을 회피하지만 단말의 수가 증가함에 따라 충돌율은 증가하고 전체 네트워크 성능은 저하된다. 본 논문에서는 이 문제를 해결하기 위해 예약 방식을 통한 데이터 전송 방법을 제안한다. 제안된 방법에서 채널 시간을 예약 구간과 경쟁 구간으로 나눈다. 기본적으로 경쟁 구간에서 단말들은 DCF와 마찬가지로 경쟁 방식을 통해 데이터를 전송할 때 예약 구간에 대한 채널 예약을 AP에게 요청한다. 또한 예약 구간에서 데이터를 전송한 단말은 다음 예약 구간에서의 예약을 요청한다. AP는 채널 예약을 수행한다. 채널 예약에 성공한 단말은 예약 구간에서 비경쟁 방법으로 데이터 패킷을 전송한다. 따라서 DCF의 충돌율을 낮추고 전체적인 네트워크 성능을 향상시킨다.

• International Journal of High-Rise Buildings
• /
• v.11 no.2
• /
• pp.137-144
• /
• 2022

As one of the most important vertical transportation equipment in super high-rise buildings, the construction elevator directly affects the project period, cost, and effectiveness. The paper proposes a new construction elevator with single-guide rail and multi-cages. It can solve the problems of single construction elevator capacity shortage and efficacy decrease with height reduction, the occupancy of plan and elevation position of multiple construction elevators, and extension of total construction period by cycling operation of multi-cages on a single-guide rail. The paper focuses on the design and research of the main components of the equipment, such as the rotating guide rail mechanism, vertical bearing mast tie system, segmented electrical power supply system, group control scheduling system, and safety anti-collision system.

• Journal of Advanced Navigation Technology
• /
• v.19 no.6
• /
• pp.465-472
• /
• 2015

In order to improve the performance of TCAS it should improve the performance of the sensor, which transmits a variety of information. In this paper, To improve the performance of the existing radar sensors such as being used in behalf of the next generation air traffic control system, ads-b the applied. In addition, ADS-B in a high precision by using information from the correction GPS system, SBAS assume would be able to apply an improved location accuracy for TCAS and analyzed TCAS and ADS-B. Played the simulation results, TCAS equipment receives the help of these ADS-B can calculate a CPA to determine the position of the aircraft in advance, and it was confirmed that it is possible to reduce the unnecessary RA operation, also, the pilot reduction and the workload, it has advantages such as fuel consumption and time associated with the reduced operation unnecessary RA was confirmed.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.42 no.5
• /
• pp.1058-1068
• /
• 2017

In V2X communication, a random based resource selection scheme is needed with considerations of cases that support devices without sidelink reception capabilities and require reduction of UE's power consumption. In this paper, as improvement of D2D's resource section scheme that one TRP is repeated to data subframe pool within a PSCCH period, it is proposed that different TRPs is applied for enhanced random resource selection based on pseudo-random sequence having UE-specific seed value. By results of proposed scheme's performance by numerical analysis, it is confirmed that collision probability among resources allocated to each UE for data TB is reduced, and a number of UEs which can avoid resource collision as much as possible and have simultaneous resource allocation is increased.

• Journal of the Society of Naval Architects of Korea
• /
• v.48 no.3
• /
• pp.246-253
• /
• 2011

This paper presents estimation of deterministic damage extents and locations due to collision and grounding which are defined by ABS guideline and DNV ship rules. It is noted that the overall extents of damages from DNV are larger than those from ABS. Nonlinear FEAs are carried out to predict residual longitudinal strength of hull girder with asymmetric severe damages. The accuracy of the applied FEA procedure is proved by comparing FEA result with test result of a 1/3-scaled frigate. The investigated vessels are a VLCC and a large-sized bulker for which evenly distributed heeling angles from $0^{\circ}$(sagging) to $180^{\circ}$(hogging) by $30^{\circ}$ due to damage-induced flooding are taken into account. The reduction ratios of the ultimate residual strength for the damaged cases to those for the intact sagging case are shown. It is proved that the grounding damage case under DNV assumption reveals most critical the residual strength. The design formulas are presented to assure minimum residual ultimate moment after damage.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.7A
• /
• pp.540-547
• /
• 2009

In this paper, we work for the efficient use of the initial ranging contention slot in OFDMA based wireless mobile networks. Specially, the collision reduction method using an automatic adaptive optimal algorithm is studied for initial ranging contention slot used at initial connection of the mobile terminals. As a result, we propose the algorithm that achieves the collision minimization and the auto-dynamic slot arrangement of the initial ranging slots. To evaluate the proposed algorithm, we compare the simulation results of IEEE802.16e fixed initial ranging slot allocation method versus the proposed algorithm. The simulator is developed based on the IEEE802.16e standard MAC frame structure and processing procedures. As the simulation results, we can expect the proposed algorithm can be applied for the unmanned coastal base station because the proposed algorithm has the effect of minimizing administration cost for the base station.

• Journal of the Korean Magnetics Society
• /
• v.18 no.1
• /
• pp.14-18
• /
• 2008

Bismuth-substituted yttrium iron garnet(Bi:YIG) films, which show excellent magnetic and magneto-optical properties as well as low optical losses by optimizing their deposition and post-annealing condition, have been attracting great attention in optical device research area. In this study, the Bi:YIG thick films were deposited with the aerosol deposition method for the final purpose of applying them to optical isolators. Since the aerosol deposition is based on the impact adhesion of sub-micrometer particles accelerated by a carrier gas to a substrate, the flow rate of carrier gas, which is in proportion to mechanically collision energy, should be treated as an important parameter. The Bi:YIG($Bi_{0.5}Y_{2.5}Fe_5O_{12}$) particles with $100{\sim}500$ nm in average diameter were carried and accelerated by nitrogen gas with the flow rate of 0.5 l/min${\sim}$10 l/min. The coercive force decreased from 51 Oe to 37 Oe exponentially with increasing gas flow rate. This is presumably due to the fact that the optimal collision energy results in reduction of impurity and pore, which makes the film to be soft magnetically. The saturation magnetization decreased due to crystallographical distortion of the film with increasing gas flow rate.