• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.568-574
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• 2024

The development of radiation-tolerant radio-frequency (RF) systems can be a solution for applications in extreme radiation environments, such as nuclear power plant monitoring and space exploration. Among the crucial components within an RF system, the low noise amplifier (LNA) stands out due to its vulnerability to TID effects, mainly relying on transistors as its main devices. In this study, the TID effects in the LNA using standard 0.18 ㎛ complementary metal oxide semiconductors (CMOS) technology are estimated and analyzed. The results show that the LNA can withstand absorbed radiation up to 100 kGy. The S₂₁, S₁₁, noise figure (NF), stability (K), and linearity of the third input intercept point (IIP3) slightly shifted from the initial values of 0.8312 dB, 0.793 dB, 0.00381 dB, 1.34406, and 2.36066 dBm, respectively which are still comparable to the typical performances. Moreover, the standard 0.18 ㎛ technology has demonstrated its radiation tolerance, as it exhibits negligible performance degradation in the conventional LNA even when exposed to radiation levels up to 100 kGy. In this context, simulation approach offers a means to predict the TID effects and estimate the radiation exposure limit for electronic devices, particularly when transistors are used as the primary RF components.

• The Journal of the Acoustical Society of Korea
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• v.35 no.2
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• pp.102-109
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• 2016

This paper proposes a noise suppression method through SNR (Singal-to Noise Ratio) estimation in the two microphone array environment of close spacing. The conventional method uses a noise suppression method for a gain function obtained through the SNR estimation based on coherence function from full band. However, this method cause performance decreased by the noise damage that affects all the feature vector component. So, we propose a noise suppression method that allocates a frequency domain signal into N constant multi frequency band and each frequency band gets a gain function through SNR estimation based on coherence function. Performance evaluation of the proposed method is shown by comparison with PESQ (Perceptual Evaluation of Speech Quality) value which is an objective quality evaluation method provided by the ITU-T (International Telecommunications Union Telecommunication).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.358-365
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• 2008

A differential-gain-controlled LNA is designed and implemented in 0.18 um CMOS technology for $3.1{\sim}4.8GHz$ UWB system. In high gain mode, measurements show a differential power gain of $14.1{\sim}15.8dB,\;13.3{\sim}15dB$, respectably, an input return loss higher then 10dB, an input IP3 of -19.3 dBm, a noise figure of $4.85{\sim}5.09dB$, while consuming only 19.8 mW of power from a 1.8V DC supply. In low gain mode, measurements show a differential power gain of $-6.1{\sim}-4.2dB,\;-7.6{\sim}-5.6dB$, respectably, an input return loss higher then 10dB, an input IP3 of -1.45 dBm, a noise figure of $8.8{\sim}10.3dB$, while consuming only 5.4mW of power from a 1.8V DC supply.

• Korean Journal of Adult Nursing
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• v.13 no.2
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• pp.209-222
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• 2001

The environment in the ICU leads to negative changes in a patient's usual sleep pattern and so contributes negatively to the patient's health condition as compared to patients in general wards. Therefore, it is thought that an important nursing intervention would be to identify the relation between noise and sleep patterns which play an important role in illness recovery. The purpose of the present study was to explore the relationship between noise in the ICU and the sleep pattern of patients admitted to the ICU. A descriptive correlation design was used to examine the relationship. Thirty-four subjects were recruited from a Medical ICU (MICU), Surgical ICU (SICU) and Coronary Care Unit (CCU) at a large university hospital in Suwon. Data were collected from September 28 to October 31 in 1999. In the present study, noise was categorized into noise level and patients' perception of noise. The objective noise level was measured using the A-Weighted Sound Level Meter. The patients' preception of noise was measured using a self-reported questionnaire developed by the researcher. Sleep patterns in this study includes both quantity and quality of sleep. These were measured using open ended questionnaires and the 'Korean Sleep Scale A' developed by Oh, Song, Kim(1998). The data was analyzed using the SPSS-WIN to test the research question, Pearson product moment correlation coefficient was run. Ancillary analysis were conducted with demographic variables to determine their relation to the main study variables. For the ancillary analysis, t-test and one-way ANOVAs were performed. The results of the present study are summerized as follows : 1. The total mean of objective noise level (10pm-6am) was 56.2dB. The means for night time noise level in individual ICUs for the SICU, MICU and CCU, were 58.7dB, 58.6dB and 48.3dB, respectively. The total mean for patients' noise perception was 42.8 out of a maximum possible score of 76. For item means of noise perception, the one ranked highest was "conversations between doctors and nurses" (3.2). The one ranked lowest was "noise from the radio" (1.2). Regarding the degree of perception for each type of noise source, the one ranked highest was "equipment noise" (2.6), the second was "conversation between medical staff" (2.4), the third was "conversation between patients, caregivers and visitors" (2.3), and the one ranked lowest was "environment noise" (1.8). 2. Looking at quantity of sleep of ICU patients, the mean nocturnal sleep time was found to be 4.9 hours. The total mean of sleep quality for ICU patients was 21.0 out of a maximum possible score of 40. 3. The relationship between perception of noise and quantity of sleep was statistically significant(r= - .41, p<.05). The relationship between perception of noise and quality of sleep was also statistically significant(r= - .47, p<.01). The results of the study indicate that personal perception of noise is related to sleep patterns. Therefore, it is suggested that nursing interventions be developed to reduce the degree of personal perception of noise and, thus, decrease sleep pattern disturbances in patients in the ICU.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4842-4848
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• 2015

This paper presents a comparison of communication performance between the reconfigurable beam-steering antenna and the omni-directional (loop) antenna during standstill and walking motion. Both omni-directional and reconfigurable antennas were manufactured on the same fabric (${\varepsilon}_r=1.35$, $tqn{\delta}=0.02$) substrate and operated around 5 GHz band. The reconfigurable antenna was designed to steer the beam directions. To implement the beam-steering capability, the antenna used two PIN diodes. The measured peak gains were 5.9-6.6 dBi and the overall half power beam width (HPBW) was $102^{\circ}$. In order to compare the communication efficiency, both the bit error rate (BER) and the signal-to-noise ratio (SNR) were measured using a GNU Radio Companion software tool and user software radio peripheral (USRP) devices. The measurement were performed when both antennas were standstill and walking motion in an antenna chamber as well as in a smart home environment. From these results, the performances of the reconfigurable beam steering antenna outperformed that of the loop antenna. In addition, in terms of communication efficiencies, in an antenna chamber was better than in a smart home environment. In terms of movement of antennas, standstill state has better results than walking motion state.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.2
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• pp.171-178
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• 2016

An aircraft in flight and ATC(: Air Traffic Controllers) working in the Ground Control Center carry out a voice communication using the radio. Voice signal to be transmitted from the aircraft is received to a plurality of terrestrial sites around the country at the same time. The ATC receives the various quality of voice signal from the aircraft depending on the distance, speed, weather conditions and adjusted condition of the antenna and the radio. The ATC carries out a voice communication with aircraft in the optimal conditions finding the best voice signal. However, the present system chooses the values of the CD(: Carrier Dectect) which is determined to be superior to, based on the input voice level, as optimal channel. Thus this system can not be seen to select the optimal channel because it doesn't consider the effect of the noise which influences on the communication quality. In this paper, after removing the noise in the voice signal, we could give the digitized information and an improved voice signal quality, so that users can select an optimal channel. By using it, when operating the training eavesdropping system or the aircraft control, we can expect prevention accident and improvement of training performance by selecting the improved quality channel.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.3
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• pp.230-238
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• 1996

In this paper, the performance improvement of BFSK signal by using diversity reception and coding technique in Rayleigh fading and impulsive noise environments has been evaluated and compared with that in Gaussian noise environment. It is found that as the CNR increases, BFSK signal performance shows an error floor regardless of impulsive noise effects in Rayleigh fading environment. Also diversity reception technique can improve the error performance not only in a Gaussian noise environment but also in a fading and impulsive noise environment. When diversity reception and coding techniques are used together in impulsive noise and Rayleigh fading environment, the improvement of error performance becomes about 11[dB] in terms of CNR as compared with that of only coding technique is applied.

• 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 Electromagnetic Engineering and Science
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• v.23 no.4
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• pp.491-498
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• 2012

Recently, many papers have been proposed in order to improve the OFDM system performance in T-DMB DOCR (Digital On Channel Repeater), by using removing the feedback signal so that the transmitter power can be increased or by using the equalizer to remove ICI. Despite these efforts, however, signal quality at the receiving terminal has not been improved because of constellation smearing in T-DMB DOCR. In this paper, in order to suppress constellation smearing, we propose an effective equalizer algorithm that can improve system performance. We perform adaptive channel estimation and non-coherent decision directed noise cancellation method that can estimate the channel subsequently during data symbols period in the frequency domain. So we can obtain better quality of the signal at the receiving terminal. In order to secure QoS(Quality of Service) required in T-DMB handsets, we evaluate SNR and BER in T-DMB DOCR(Digital On Channel Repeater) and verified by simulation. In this simulation results, this system is satisfied the performance of BER=$10^{-5}$ at less than SNR=14 dB at the receiver after compensation of phase noise -18 dBc.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.451-460
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• 2006

We have designed local exposure systems for long-time mice experiments in PCS and cellular frequency band(PCS: 1,762.5 MHz, cellular: 848.5 MHz). The fabricated systems are local exposure systems of carousel type, and 40 mice can be exposed at a time. In order not to give extra stress to the mice ender experiment, the systems were fabricated to meet the environmental conditions such as illumination, ventilation, noise etc. SAR measurement was performed using a temperature probe. Measurements at 3 points in the head of mouse cadaver and solid phantom were made, and it has been confirmed that the measurement results are in good agreement with the simulation results in the real exposure environment. The exposure systems are currently used for long-term mice experiments.