• The Bulletin of The Korean Astronomical Society
• /
• v.41 no.1
• /
• pp.71.2-71.2
• /
• 2016

Merging galaxy clusters, such as PLCKG287.0+32.9, provide a window into the formation process of the large scale structure of the universe. PLCKG287.0+32.9 is an enormous merging galaxy cluster with mass estimated to be ~10^15 Msun. It hosts a pair of mega-parsec sized radio relics with projected offsets from the X-ray center of approximately 350kpc and 2.7Mpc, suggesting a NW-SE merging scenario with relics originating from two separate passes (Bonafede et al. 2014). A detected radio halo coincides with the center of x-ray emission. We present the motivation for our weak lensing study of the merging galaxy cluster PLCKG287.0+32.9 using recent Subaru optical imaging. We discuss the basics of weak-lensing and the criteria for source selection. In addition, we describe our method of PSF modeling and mass reconstruction.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.3 no.2
• /
• pp.231-243
• /
• 2000

This paper describes a simulation of secondary motion of piston assemblies using PISDYN by Ricardo. Motions of the piston, pin, rod and skirt are separately calculated, by integrating equations of motion for individual components and dynamic degrees of freedom. The effects of engine speed at full load and pin offsets on the piston assembly secondary motions, forces and friction were investigated in parametric study for 4-cylinder gasoline engine. Results show that lateral displacement and friction loss of the piston increase as a function of engine speed. The lateral motion of the piston is affected by the change in pin offset. The minimum friction loss for the condition of 4800rpm WOT occurs at a pin offset of 1.6mm.

• Journal of Power Electronics
• /
• v.13 no.1
• /
• pp.86-93
• /
• 2013

A half-cycle-waveform inversion based three reference modulations seven-level SPWM (TRM-SPWM) scheme with one carrier is proposed in this paper. To keep the same comparison logics for the modulations and carrier during the negative half cycle and the positive one for the modulations, in the negative half cycle of the modulations, the DC offsets related to the amplitude of the carrier are set on the three modulations, respectively. The seven-level SPWM waveform with dead time thereby is implemented with only one Digital Signal Processor (DSP) without any other attached logic circuit. The basis principle of the proposed TRM-SPWM is analyzed in detail, and the frequency spectrums of the conventional and the proposed schemes are derived and compared with each other through simulation. The DSP based implementation is presented and detailed experimental waveforms verify the accuracy and feasibility of the proposed TRM-SPWM scheme.

• The Journal of Fisheries Business Administration
• /
• v.39 no.3
• /
• pp.67-90
• /
• 2008

In this study, we aimed to build the basic calculation model for linkage effects of fishery industry among Korea, China and Japan. For the calculation, we reconstructed the asian international input-output table, and on the basis of the reconstructed table, we made some analyses on the inter-relations among 3 nations focusing fishery industry. As the results, some positive backward linkage offsets of the fishery industries were found among 3 nations, and especially, production inducing effect of Chinese fishery industry to Japanese supplier was remarkable.

• Journal of the Society of Naval Architects of Korea
• /
• v.28 no.2
• /
• pp.21-27
• /
• 1991

This paper outlines the method of formulating the bi-cubic B-spline surface of ship hull, employing the open uniform knot vector as well as the periodic uniform knot vector. An appropriate set of B-spline control vertices to generate the B-spline surface is determined by obtaining the pseudoinverse matrix of basis functions. The comparison between the given offsets and the resulting coordinates from the generated ship hull surface shows a good agreement. To check the fairness of the surface Gaussian curvature is calculated on many small subpatches and displayed on the black-and-white plot of the isoparametric net of the surface.

• ETRI Journal
• /
• v.38 no.1
• /
• pp.30-40
• /
• 2016

Co-channel interference between macro-femtocell networks is an unresolved problem, due to the frequency reuse phenomenon. To mitigate such interference, a secondary femtocell must acquire channel-state knowledge about a co-channel macrocell user and accordingly condition the maximum transmit power of femtocell user. This paper proposes a pilot-based spectrum sensing (PSS) algorithm for overlaid femtocell networks to sense the presence of a macrocell user over a channel of interest. The PSS algorithm senses the pilot tones in the received signal through the power level and the correlation metric comparisons between the received signal and the local reference pilots. On ensuring the existence of a co-channel macrocell user, the maximum transmit power of the corresponding femtocell user is optimized so as to avoid interference. Time and frequency offsets are carefully handled in our proposal. Simulation results show that the PSS algorithm outperforms existing sensing techniques, even at poor received signal quality. It requires less sensing time and provides better detection probability over existing techniques.

• ETRI Journal
• /
• v.29 no.5
• /
• pp.596-606
• /
• 2007

It is well known that an OFDM receiver is vulnerable to synchronization errors. Despite fine estimations used in the initial acquisition, there are still residual synchronization errors. Though these errors are very small, they severely degrade the bit error rate (BER) performance. In this paper, we propose a residual error elimination scheme for the digital OFDM baseband receiver aiming to improve the overall BER performance. Three improvements on existing schemes are made: a pilot-aided recursive algorithm for joint estimation of the residual carrier frequency and sampling time offsets; a delay-based timing error correction technique, which smoothly adjusts the incoming data stream without resampling disturbance; and a decision-directed channel gain update algorithm based on recursive least-squares criterion, which offers faster convergence and smaller error than the least-mean-squares algorithms. Simulation results show that the proposed scheme works well in the multipath channel, and its performance is close to that of an OFDM system with perfect synchronization parameters.

• Journal of the Korea Computer Graphics Society
• /
• v.9 no.3
• /
• pp.7-13
• /
• 2003

본 논문은 사람의 실제 얼굴에서 캡쳐된 얼굴 모션 데이터를 새로운 얼굴에 재적용하는 리타켓팅 기법을 제안한다. 본 기법은 형태가 매우 상이한 얼굴 모델에도 적용이 가능하며 특히 주름같은 세밀한 모션의 리타켓팅에 적합하다. 본 기법은 다중해상도 메쉬 즉 노말메쉬(normal mesh)를 사용함으로써 소스와 타켓의 계층적으로 대응관계를 결정하고 계층적으로 리타켓팅한다. 노말 메쉬는 주어진 메쉬를 베이스 메쉬 (base mesh)와 일련의 노말 오프셋 (normal offsets)을 이용하여 근사시킨 계층적 메쉬이다. 본 리타켓팅 기법은 우선 베이스 모션을 소스 모델에서 타겟 모델로 리타켓팅한 후 그 모션 위에 노말 오프셋의 모션을 계층적으로 더해준다. 이 기법은 형태가 매우 세밀한 모션에 대하여 안정적이면서도 정교한 리타켓팅 결과를 생성한다.

• Journal of Communications and Networks
• /
• v.6 no.2
• /
• pp.112-122
• /
• 2004

A nonlinear spectral-line method utilizing the fourth absolute moment of the receiver discrete Fourier transform output is proposed as a non-data-aided fine carrier frequency synchronization algorithm for OFDM receivers. A simple modification of the algorithm resulting in low implementation complexity is also developed. Analytic expressions are derived for the steady-state frequency error variances of the algorithms and verified to be very accurate via computer simulations over AWGN and frequency selective multipath channels. Numerical results show that the proposed algorithms provide reliable and excellent steady-state performance, especially with PSK modulation. Also, the proposed algorithms are insensitive to symbol timing offsets, only requiring a coarse symbol timing recovery.

• Journal of Korean Institute of Industrial Engineers
• /
• v.18 no.2
• /
• pp.1-9
• /
• 1992

The purpose of this paper is to investigate the dynamic situation of the biomechanical responses of a pilot that occur before the black out during high gravity maneuvering. The computer biodynamic simulations using the Articulated Total Body(ATB) model show the following results : 1) the center of gravity(c. g) offsets of a helmet have significant effects on the head deflection angle which is closely connected with the head down : 2) the average and maximum gravity forces are smaller in the curvilinear type of an acceleration than in the straight type of the acceleration, and it is applied to the case of the head deflection angle. We suggest that the new concept of protective device should be necessary to prevent the head down during high gravity maneuvering.