• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.04a
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• pp.159-164
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• 1993

This paper presents a computer design program for In-Core Instrumentation(ICI) guide tube routing and locations on support system, and checking the interference between ICI guide tubes in the reactor coolant system of typical Pressurized Water Reactor. The program, ICITRIC, has been written in FORTRAN language which is available under UNIX environment. Results of this program are compared with those of the commercial code, PATRAN, and both results are almost same Also the results may provide input data for ICI system static and dynamic analysis performed by the commercial code, SUPER PIPE. This program can simulate ICI guide tube routing and locations on support system, and checking the interference between ICI guide tubes. Through a process of iteration, the designer can apply initial conditions, and modify the routing until satisfied with the overall system performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.8
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• pp.3704-3724
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• 2018

This paper proposes an advanced turbo receiver with joint inter-carrier interference (ICI) self cancellation and channel equalization for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems over rapidly time-varying channel environment. The ICI caused by impairment of local oscillators and carrier frequency offset (CFO) is the major problem for MIMO-OFDM communication systems. The existing schemes (conjugate cancellation (CC) and phase rotated conjugate cancellation (PRCC)) that deal with the ICI cancellation and channel equalization can't provide satisfactory performance over time-varying channels. In term of error rate performance and low computational complexity, ICI self cancellation is the best choice. So, this paper proposes a turbo receiver to deal with the problem of joint ICI self cancellation and channel equalization. We employ the adaptive phase rotations in the receiver to effectively track the CFO variations without feeding back the CFO estimate to the transmitter as required in traditional existing scheme. We also give some simulations to verify the proposed scheme. The proposed schene outperforms the existing schemes.

• Journal of Korean Neurosurgical Society
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• v.64 no.2
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• pp.271-281
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• 2021

Objective : Immune checkpoint inhibitors (ICIs) are approved for treating non-small-cell lung cancer (NSCLC); however, the safety and efficacy of combined ICI and Gamma Knife radiosurgery (GKS) treatment remain undefined. In this study, we retrospectively analyzed patients treated with ICIs with or without GKS at our institute to manage patients with brain metastases from NSCLC. Methods : We retrospectively reviewed medical records of patients with brain metastases from NSCLC treated with ICIs between January 2015 and December 2017. Of 134 patients, 77 were assessable for brain responses and categorized into three groups as follows : group A, ICI alone (n=26); group B, ICI with concurrent GKS within 14 days (n=24); and group C, ICI with non-concurrent GKS (n=27). Results : The median follow-up duration after brain metastasis diagnosis was 19.1 months (range, 1-77). At the last follow-up, 53 patients (68.8%) died, 20 were alive, and four were lost to follow-up. The estimated median overall survival (OS) of all patients from the date of brain metastasis diagnosis was 20.0 months (95% confidence interval, 12.5-27.7) (10.0, 22.5, and 42.1 months in groups A, B, and C, respectively). The OS was shorter in group A than in group C (p=0.001). The intracranial disease progression-free survival (p=0.569), local progression-free survival (p=0.457), and complication rates did not significantly differ among the groups. Twelve patients showed leptomeningeal seeding (LMS) during follow-up. The 1-year LMS-free rate in treated with ICI alone group (69.1%) was significantly lower than that in treated with GKS before ICI treatment or within 14 days group (93.2%) (p=0.004). Conclusion : GKS with ICI showed no favorable OS outcome in treating brain metastasis from NSCLC. However, GKS with ICI did not increase the risk of complications. Furthermore, compared with ICI alone, GKS with ICI may be associated with a reduced incidence of LMS. Further understanding of the mechanism, which remains unknown, may help improve the quality of life of patients with brain metastasis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6A
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• pp.465-473
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• 2005

In this paper, the reduction scheme of Interchannel Interference(ICI) caused by the phase noise in Orthogonal Frequency Division Multiplexing(OFDM) systems for archiving high data rates is proposed. The performance of conventional common phase error(CPE) compensation method is degraded by the phase noise with wide 3dB bandwidth in OFDM systems width a higher-order constellation. After estimating dominant ICI coefficients using pilot subcarriers and data subcarriers adjacent to pilot subcarriers, the proposed scheme compensates OFDM signals distorted by the phase noise using estimated coefficients in the time or frequency domain. Also, in order to determine the length of dominant ICI coefficients effectively, the estimation method of the 3dB bandwidth of the phase noise is proposed. The proposed phase noise reduction method is shown to improve the Bit Error Ratio(BER) performance compared with the conventional CPE compensation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6A
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• pp.583-591
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• 2008

OFDM (orthogonal frequency division multiplexing) has serious problem of high PAPR (peak-to-average power ratio). Recently, CI/OFDM (carrier interferometry OFDM) system has been proposed for the low PAPR. However, CI/OFDM system shows another problem of ICI because of phase offset mismatch due to the phase noise. In this paper, to simultaneously reduce the PAPR and ICI effects, we propose an A-CI/OFDM (advanced-CT/OFDM). This method improves the BER performance by use of the margin of phase offset at CI codes. Propose system to reduce the effect the phase noise, even though it shows a little bit higher PAPR than conventional CI/OFDM, so we apply the PTS among the PAPR reduction techniques to proposed system to mitigate this problem. Therefore, it improves the total BER performance because the proposed method can decrease the effect of phase noise and get the gain in PAPR reduction performance. From the simulation results, we can show the performance comparison between the conventional OFDM, CI/OFDM and A-CI/OFDM.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.1
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• pp.21-28
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• 2009

DFT-spread OFDM(Discrete Fourier Transform-Spread Orthogonal Frequency Division Multiplexing) is very effective for solving the PAPR(Peak-to-Average Power Ratio) problem. Therefore, the SC-FDMA(Single Carrier-Frequency Division Multiple Access) which is basically same to the DFT spread OFDM was adopted as the uplink standard of the 3GPP LTE ($3^{rd}$ Generation Partnership Project Long Term Evolution). Unlike the ordinary OFDM system, the SC-FDMA using DFT spreading method is vulnerable to the ICI(Inter-Carrier Interference) problem caused by the phase noise and IQ(In-phase/Quadrature) imbalance and effected FDE(Frequency Domain Equalizer). In this paper, the ICI effects from the phase noise and IQ imbalance which can be problems in uplink transmission are analyzed according the back-off level of HPA. Next, we propose the equalizer algorithm to remove the ICI effects. This proposed equalizer based on the FDE can be considered as up-graded and improved version of PNS(Phase Noise Suppression) algorithm. This proposed equalizer effectively compensates the ICI resulting from the phase noise and IQ imbalance. Finally, through the computer simulation, it can be shown that about SNR=14 dB is required for the $BER=10^{-4}$ after ICI compensation when the back-off is 4.5 dB, $\varepsilon=0.005$, $\phi=5^{\circ}$, and $pn=0.06\;rad^2$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.12 s.91
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• pp.1152-1160
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• 2004

OFDM technique was adopted as the standard of IEEE 802.1 la and it has been widely used for wireless LAN, European DVB/DAB system, Korean DMB system. In the standard of IEEE 802.11a the data packet is composed of two parts, preamble and data. Preamble is composed of short pilots and long pilots, which are used for synchronization and estimation of frequency offset and channel. We can also compensate phase noise effect in the transceiver by using above pilots. The phase noise is more complicate than frequency offset and seriously affects system performance. In this paper, we newly propose CPE and ICI simultaneous compensation method to compensate phase noise generated by transceiver oscillator and compare with previous studies. As results, phase noise effect can be significantly compensated by CPE cancellation method, PNS algorithm and our proposed CPE and ICI compensation method. Especially, the proposed CPE and ICI compensation method can achieve the best BER performance compared with original OFDM, CPE cancellation method and PNS algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2C
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• pp.95-112
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• 2007

Spatial Multiplexing techniques, which is a kind of Multiple antenna techniques, provide high data transmission rate by transmitting independent data at different transmit antenna with the same spectral resource. OFDM (Orthogonal Frequency Division Multiplexing) is applied to MIMO (Multiple-Input Multiple-Output) system to combat ISI (Inter-Symbol Interference) and frequency selective fading channel, which degrade MIMO system performance. But, orthogonality between subcarriers of OFDM can't be guaranteed under high-mobility condition. As a result, severe performance degradation due to ICI is induced. In this paper, both ICI and CAI (Co-Antenna Interference) which occurs due to correlation between multiple antennas, and performance degradation due to both ICI and CAI are analyzed. In addition to the proposed CIR (Channel Impulse Response) estimation method for avoiding loss in data transmission rate, HIC (Hybrid Interference Cancellation) approach for guaranteeing QoS of MIMO-OFDM receiver is proposed. We observe the results on analytical performance degradation due to both ICI & CAI are coincide with the simulation results and performance improvement due to HIC are also verified by simulation under SCM-E Sub-urban Macro MIMO channel.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.3
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• pp.63-68
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• 2015

We consider a cell edge environment. In cell edge, a user interfered by signal which is generated by a base stations not including the user. In cell edge environment, that is, there are inter cell interference (ICI) as well as multi user interference (MUI). Coordinated multi-point transmission (CoMP) is a technique which mitigates ICI between base stations. In CoMP, therefore, base stations can coordinate with each other by sharing user state information (CSI) in order to mitigate ICI. To improve sum rate performance in CoMP, each base station should generate optimal user group and transmit data to users selected in the optimal user group. In this paper, we propose a user selection algorithm in CoMP. The proposed method use signal to interference plus noise ratio (SINR) as criterion of selecting users. Because base station can't measure accurate SINR of users, in this paper, we estimate SINR equation considering ICI as well as MUI. Also, we propose a user selection algorithm based on the estimated SINR. Through MATAL simulation, we verify that the proposed method improves the system sum rate by an average of 1.5 ~ 3 bps/Hz compared to the conventional method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5A
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• pp.441-449
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• 2011

Sample timing offset (STO) and carrier frequency offset (CFO) are caused by inter-symbol interference (ISI), inter-carrier interference (ICI) and phase error in orthogonal frequency division multiplexing (OFDM) system. OFDM characteristic is sensitive about STO and CFO. So when ICI occurs, compensation is hard and complex equalizer is needed. In this paper, we propose an effective correction method using feedback process with pilot and synchronization symbol. After feedback with estimated value in frequency domain, STO and CFO are corrected by control sample & and holder and oscillator. As a result of simulation, we confirm that STO and CFO can be corrected without equalizer through feedback.