• ETRI Journal
• /
• v.31 no.2
• /
• pp.162-172
• /
• 2009

A linear-prediction-based blind equalization algorithm for single-input single-output (SISO) finite impulse response/infinite impulse response (FIR/IIR) channels is proposed. The new algorithm is based on second-order statistics, and it does not require channel order estimation. By oversampling the channel output, the SISO channel model is converted to a special single-input multiple-output (SIMO) model. Two forward linear predictors with consecutive prediction delays are applied to the subchannel outputs of the SIMO model. It is demonstrated that the partial parameters of the SIMO model can be estimated from the difference between the prediction errors when the length of the predictors is sufficiently large. The sufficient filter length for achieving the optimal prediction is also derived. Based on the estimated parameters, both batch and adaptive minimum-mean-square-error equalizers are developed. The performance of the proposed equalizers is evaluated by computer simulations and compared with existing algorithms.

• Proceedings of the IEEK Conference
• /
• 2000.07b
• /
• pp.990-994
• /
• 2000

The design of LAI(Local Area Identifier), the first paging area for searching the mobile terminal has a close relation with the performance of paging channel in CDMA cellular network. This paper discusses the performance of the forward channel of IS-95 CDMA standard, known as the paging through the related messages such as call control message, channel assignment message. Modeling and simulation work were conducted to quantify the performance of paging channel in terms of traffic handling capacity and blocking levels. This result serves as illustrative guidelines for the proper engineering of common control channel, which has a major impact on the overall performance of cellular network.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2006.05a
• /
• pp.139-142
• /
• 2006

Numerous simulation studies and researches have recently revealed the rapid development and evolution in the emerging area of intelligent unmanned aerial vehicle (UAV). This study aims to develop a flight performance evaluation about the wireless unmanned helicopter. The process includes the design and testing of flight hardware and software that interprets sensor data. For the unmanned helicopter used in this research, an inertial sensor that provides posture (roll, pitch and yaw angles) and a Bluetooth is used to provide wireless connection between the user's pc and the helicopter were installed in the helicopter the helicopter's pitch, roll and yaw were the communication data. The accuracy of the system was confirmed by a computer simulation. The software also has been developed to support operators and displays helicopter position and posture by graphics.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2006.05a
• /
• pp.1019-1022
• /
• 2006

Advances in interactive multimedia and Internet technologies present an array of options that allow the development of very effective training programs. Interactive training is the delivery and management of training using Internet. The trainee actively participates in the training/learning sessions by means of a user-friendly interface that empowers the participant with a sense of control over what they are teaming and the pace at which they are teaming. In this paper, we show process on the development of 3 dimensional e-learing system for Ubiqitous Environment using 3 dimensional supersonic sensor.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2006.05a
• /
• pp.451-454
• /
• 2006

Ultrasonic Positioning System (UPS) is an absolute positioning system using ultrasonic waves and has better performance in low price than the other absolute positioning systems. UPS can be further used as pseudo-satellites in the place where GPS is not available. This study aims to evaluate the efficiency and effectiveness of using UPS as a 3D free-hand writing or drawing tool. The process includes the design and testing of VPS as an efficient 3D free-hand writing or drawing tool in the air. The paper will further explain the system architecture of the UPS and how to use GPS as 3D free-hand writing or drawing tool. The efficiency and effectiveness of the system was confirmed by a computer software simulation. The software will further display the result of drawing or writing from the user by graphics. As a result, it is possible to implement UPS as a 3D free-hand writing or drawing tool in the air.

• Toxicological Research
• /
• v.5 no.1
• /
• pp.43-48
• /
• 1989

The average value of total mercury contents in scalp hair of Korean male was found to be 1.66+1.10 ppm (S.D.) and that of methylmercury was 1.02+0.72 ppm (61.0% of the total mercury). In case of total mercury contents of female was 1.06+0.46 ppm and that of methylmercury was 0.51+0.27 ppm (48.4% of total mercury level). When compared with data reported by Japanese, the levels were about half. The levels of mercury in scalp hair of male subjects were significantly different with their occupations, but in case of female, the variation was not so much.

• Membrane and Water Treatment
• /
• v.8 no.4
• /
• pp.369-380
• /
• 2017

Performance evaluation of four commercially available tubular membranes (AFC 80, AFC 30, PU 608, ES 404) was accomplished in self-assembled membrane testing unit. Effects of varying transmembrane pressure, feed concentration and anion type were investigated. Aqueous solutions of salts such as calcium chloride, calcium sulfate, tin chloride and tin sulfate were prepared for this study. It was noted that the investigated parameters e.g., pressure and concentration had significant effects on membrane's performance. Nevertheless, anion type effectively played its role in the rejection of salts since salt having SO4-2 anions had a better rejection than the salts containing Cl-1. It is observed that rejection was dominated by Donnon exclusion for strongly charged nanofiltration membranes whereas for weakly charged ultrafiltration membranes, size exclusion was the key mechanism to reject the ions.

• ETRI Journal
• /
• v.43 no.2
• /
• pp.344-356
• /
• 2021

CRAFT is a tweakable block cipher introduced in 2019 that aims to provide strong protection against differential fault analysis. In this paper, we show that CRAFT is vulnerable to side-channel cube attacks. We apply side-channel cube attacks to CRAFT with the Hamming weight leakage assumption. We found that the first half of the secret key can be recovered from the Hamming weight leakage after the first round. Next, using the recovered key bits, we continue our attack to recover the second half of the secret key. We show that the set of equations that are solvable varies depending on the value of the key bits. Our result shows that 99.90% of the key space can be fully recovered within a practical time.

• Bulletin of the Korean Mathematical Society
• /
• v.58 no.6
• /
• pp.1341-1354
• /
• 2021

Let r ≥ 2, and let k_i ≥ 2 for 1 ≤ i ≤ r. Mixed van der Waerden's theorem states that there exists a least positive integer w = w(k₁, k₂, k₃, …, k_r; r) such that for any n ≥ w, every r-colouring of [1, n] admits a k_i-term arithmetic progression with colour i for some i ∈ [1, r]. For k ≥ 3 and r ≥ 2, the mixed van der Waerden number w(k, 2, 2, …, 2; r) is denoted by w₂(k; r). B. Landman and A. Robertson [9] showed that for k < r < $\frac{3}{2}$(k - 1) and r ≥ 2k + 2, the inequality w₂(k; r) ≤ r(k - 1) holds. In this note, we establish some results on w₂(k; r) for 2 ≤ r ≤ k.

• Bulletin of the Korean Mathematical Society
• /
• v.60 no.5
• /
• pp.1375-1390
• /
• 2023

In this note, we shall show that the generalized free products of subgroup separable groups amalgamating a subgroup which itself is a finite extension of a finitely generated normal subgroup of both the factor groups are weakly potent and cyclic subgroup separable. Then we apply our result to generalized free products of finite extensions of finitely generated torsion-free nilpotent groups. Finally, we shall show that their tree products are cyclic subgroup separable.