• 생물정신의학
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• 제24권4호
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• pp.188-195
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• 2017

Objectives Schizophrenia is characterized by disturbances in perception and cognition. Attenuated mismatch negativity (MMN) reflects central auditory dysfunction in schizophrenia. The aim of this study is to compare MMN changes before and after treatment in schizophrenia patients and to assess their association with treatment response. Methods Twenty-three schizophrenia patients underwent an oddball paradigm. MMN was calculated by the difference waveforms of the event-related potentials (ERPs) elicited by subtracting standard from deviant stimulus. The clinical symptoms were measured by the Positive and Negative Syndrome Scale (PANSS), the Psychotic Symptom Rating Scale (PSYRATS). Follow-up evaluation was conducted when the PANSS total score decreased by 30% or more (treatment response group) or before discharge (non-response group). Results The treatment response group showed significantly larger MMN amplitude improvement and latency reduction than the non-response group after treatment (Fz ; mean amplitude p = 0.035, FCz ; p = 0.041). The auditory hallucination group showed shorter latency than that of the group without hallucinations. Additionally, auditory hallucination was associated with prolonged MMN latency and shortened after treatment in the auditory hallucination response group (Fz ; p = 0.048). Conclusions These results suggest that the attenuated MMN amplitude reflects the progression of the disease. The increment of MMN amplitude and shortening of latency after treatment may reflect cognitive functional recovery of central auditory sensory processing.

• 수산해양기술연구
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• 제40권2호
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• pp.132-137
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• 2004

스트로보광에 대한 어류의 전기생리학적 반응을 조사하기 위하여, 전갱이에 각각 4단계의 섬광빈도(1.7~25Hz)와 강도(56~415lx${\cdot}$s)로 광자극을 주어, 그에 대한 망막활동전위 (ERG)를 조사한 결과는 다음과 같다. 1. ERG 진폭은 스트로보광을 조사한 순간에 최대가 되고, 그 후 가장 작았다가 점차 커져서 안정되는 경향을 보였다. 2. 섬광빈도에 따른 ERG 진폭은 광자극 후 약 12~17분부터 안정되는 경향을 보였다. 3. 전갱이가 받는 자극량은 섬광빈도 10Hz 에서 가장 많았고, 스트로보광 강도가 약해짐에 따라 감소하였다. 4. ERG 진폭변화는 10Hz가 가장 컸고, 스트로보광의 강도가 감소함에 따라 적었다.

• Computers and Concrete
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• 제31권4호
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• pp.293-306
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• 2023

This study proposes and demonstrates a smart monitoring system that uses transmission lines embedded in a reinforced concrete structure to detect the presence of defects through changes in the electromagnetic waves generated and measured by a time-domain reflectometer. Laboratory experiments were first conducted to identify the presence of voids in steel-concrete composite columns. The results indicated that voids in the concrete caused a positive signal reflection, and the amplitude of this signal decreased as the water content of the soil in the void increased. Multiple voids resulted in a decrease in the amplitude of the signal reflected at each void, effectively identifying their presence despite amplitude reduction. Furthermore, the electromagnetic wave velocity increased when voids were present, decreased as the water content of the soil in the voids increased, and increased with the water-cement ratio and curing time. Field experiments were then conducted using bored piles with on-center (sound) and off-center (defective) steel-reinforcement cage alignments. The results indicated that the signal amplitude in the defective pile section, where the off-center cage was poorly covered with concrete, was greater than that in the pile sections where the cage was completely covered with concrete. The crosshole sonic logging results for the same defective bored pile failed to identify an off-center cage alignment defect. Therefore, this study demonstrates that electromagnetic waves can be a useful tool for monitoring the health and integrity of reinforced concrete structures.

• 비파괴검사학회지
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• 제19권6호
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• pp.439-447
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• 1999

복합재료-금속 접착접합부가 사용 중 반복하중을 받을 때 발생하는 피로손상을 실시간에 평가할 수 있는 기법으로 음향초음파(acousto-ultrasonics; AU)법을 채택하였으며, 피로시험 중의 단일겹치기(single-lap) 및 이중겹치기 (double-lap) 평판형 시험편에서 취득한 신호로부터 계산된 음향초음파변수(acousto-ultrasonic parameters: AUP)와 피로손상도 사이의 상관관계를 나타내는 곡선을 얻을 수 있었다. 곡선은 피로손상에 의한 고분자기지 복합재료의 강성율 저하($E/E_o$)를 나타내는 곡선과 매우 유사하며, 이를 바탕으로 피로손상도의 실시간 예측이 가능하다. 다만 단일겹치기 시험편의 경우에는 Amplitude와 AUP2를, 이중겹치기 시험편의 경우에는 Amplitude와 AUP1을 기준 변수로 채택할 때 보다 일관성 있는 결과를 얻고 있는 점으로부터 실제 구조물에 적용함에 있어서는 각각의 형상에 따른 최적변수를 선택하여 활용해야 할 것으로 사료된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.291-298
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• 2003

The resonant column testing is a laboratory testing method to determine the shear modulus and the material damping factor of soils. The method has been widely used for many applications and its importance has been increased. Since the establishment of the testing method in 1963, the low-technology electronic devices for testing and data acquisition have limited the measurement to the amplitude of the linear spectrum. The limitations of the testing method were also attributed to the assumption of the linear-elastic material in the theory of the resonant column testing and to the use of the wave equation for the dynamic response of the specimen. For the better theoretical formulation of the resonant column testing, this study derived the equation of motion and provided its solution. This study also proposed the improved data reduction and analysis method for the resonant column testing, based on the advanced data acquisition system and the proposed theoretical solution for the resonant column testing system. For the verification of the proposed data reduction and analysis method, the numerical simulation of the resonant column testing was performed by the finite element analysis. Also, a series of resonant column testing were peformed for Joomunjin sand, which verified the feasibility, of the proposed method and showed the limitations of the conventional data reduction and analysis method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권1호
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• pp.200-220
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• 2016

Orthogonal frequency division multiplexing (OFDM) signals suffer from the problem of large peak-to-average power ratio (PAPR) which complicates the design of the analog front-end of the system. Companding is a well-known PAPR reduction technique that reduces the PAPR by transforming the signal amplitude using a deterministic function. In this paper, a novel piecewise linear companding transform is proposed. The design criteria for the proposed transform is developed by investigating the relationships between the compander and decompander's profile and parameters with the system's performance metrics. Using analysis and simulations, we relate the companding parameters with the bit error rate (BER), out-of-band interference (OBI), amount of companding noise, computational complexity and average power. Based on a set of criteria developed thereof, we formulate the design of the proposed transform. The main aim is to preserve the signal's attributes as much as possible for a predetermined amount of PAPR reduction. Simulations are carried out to evaluate and compare the proposed scheme with the existing companding transforms to demonstrate the enhancement in PAPR, BER and OBI performances.

• 수산해양기술연구
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• 제50권3호
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• pp.342-350
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• 2014

An active stimulating device, such as a fluttering net or canvas attached to the end of a cod end generating a shaking motion, could help to encourage the escape of juvenile fish positioned passively near the net. Field fishing trials using a shrimp beam trawl were carried out to examine the effect on the reduction of juvenile fish or other discard catch by generating a shaking movement of the cod end using an unbiased cap-like round canvas. The mean period of the shaking motion with the round canvas was ~14 s, and the mean amplitude was 0.4 m as measured by peak event analysis and the global wavelet method. The bycatch of juvenile fish in 14 trials decreased by ~30% and by ~25% using a steady cod end for the total bycatch using a shaking cod end in the shrimp beam trawl, while the marketing catch was similar between steady and shaking cod ends. There was no difference in the body size of the shrimp or fish and species composition between the steady and shaking cod ends. Above results demonstrate a new method for bycatch reduction using an active stimulating device, although more detailed studies are needed.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.189-197
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• 2005

The usefulness of unsteady combustion was experimentally investigated using confined premixed flames stabilized by a rearward-facing step. For this purpose, apparatus of forced pulsating mixture supply, which could be modulated its amplitude and frequency, was designed. The unsteady combustion used in this experiment plays an important role in controlling self-excited combustion oscillations and furthermore it exhibits desirable performance, from a practical point of view, such as high combustion and reduction of pollutant emission like nitric oxide.

• Journal of Korean Neurosurgical Society
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• 제30권sup2호
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• pp.281-288
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• 2001

Objectives : The purpose of this study is to evaluate the usefulness of SSEP monitoring during intracranial aneurysm surgery and compare the characteristics of wave change in relation to neurologic changes between ACA aneurysms and MCA aneurysms. Methods : During recent three years(between January 1997 and November 1999), intraoperative SSEP monitoring had been done in 63 operations for intracranial aneurysms. We had monitored the median nerve SSEP during surgery for aneurysms of MCA and the posterior tibial nerve SSEP for aneurysms of ACoA or ACA. A more than 50% reduction of any cortical SEP response was considered to be a significant SEP change, compared to its baseline value before the start of surgery. Changes in the SEPs were categorized as follows : Type IA, no significant amplitude changes without temporary clipping ; Type IB, no significant amplitude changes with temporary clipping ; Type II, significant changes with temporary clipping and complete return to control amplitude ; Type III, significant changes with temporary clipping and incomplete return to control amplitude ; Type IV, significant changes with temporary clipping and more decreased amplitude changes. Results : Among the 63 intraoperative monitoring, there were 37 cases of ACA aneurysms(An), and 26 of MCA An. The temporary proximal arterial occlusion during surgery were performed in 31(83.8%)cases of ACA An, 22(84.6%) of MCA An. Seven of the 31 ACA An(22.6%) and ten of the 22 MCA An(45.5%) had significant changes. The type were as follows : 4 patients with type II and 3 with type III in the ACA An ; 3 patients with type II and 3 with type III and 4 with type IV in the MCA An. In both group type II changes had no new postoperative neurological deficit. All 6 patients with type III had new neurological deficits ; However, One case in the ACA An and two cases in the MCA An. had transient neurologic deficit and improved markedly over the next two months. All 4 type IV changes in the MCA An. had permanant neurologic deficits. Two out of 30 cases(6.7%) in the ACA An. and one out of 16 cases(6.3%) in the MCA An. without significant amplitude change had new neurologic deficit postoperatively. Conclusion : Based on this study, Intraoperative SSEP monitoring during aneurysm surgery would provide useful information for detecting cerebral ischemia. SSEP response during surgery for MCA An. is more sensitive than ACA An. Otherwise, there were no meaningful difference in rate of false negativity.

• Annals of Clinical Neurophysiology
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• 제6권1호
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• pp.31-34
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• 2004

Backgrounds: The pathway of the sural nerve (SN) is variable, but usually divided into medial and lateral sural branches joining the posterior tibial nerve (PTN) and the peroneal nerve (PN). The sural nerve may be affected by PN palsy. The frequency or the severity of SN involvement in peroneal palsy is not known. The purpose of the study is to investigate the frequency and the severity of the SN involvement by the peroneal nerve palsy. Methods: Total 85 patients were included with peroneal palsy. Amplitudes of distal peroneal, sural, and superficial peroneal nerves (SPN) were compared between normal and paralyzed sides. The frequency and severity of SN involvement by peroneal palsy were investigated. Results: Mean age was $48.4{\pm}17.4$ years old at the time of the test. Peroneal palsy was right side in 32, left in 38, and bilateral in 15 patients. Mean amplitudes of affected distal PN, SPN, and SN were $1.51{\pm}1.64mV$, $3.50{\pm}4.86{\mu}V$, and $10.42{\pm}6.59{\mu}V$ in right side, and $1.19{\pm}1.57mV$, $4.38{\pm}5.67{\mu}V$, and $11.06{\pm}6.87{\mu}V$ in left side, respectively. Sensory nerve action potential (SNAP) amplitude of the SN in the affected side was average $73.7{\pm}33.1%$ of normal, which was significantly lower than that in the normal side(p<0.01). The decrease of the sural SNAP amplitude was more than 15% in 39 out of 70 patients with unilateral peroneal palsy. Peroneal compound muscle action potential (CMAP) amplitude was not correlated with the amplitude of the sural SNAP. By complete peroneal palsy, SN SNAP amplitude was decreased to 4% of SNAP and $57.7{\pm}31.8%$ of that in normal side. Conclusions: PN injury without PTN involvement may induce reduction of sural SNAP amplitude. Because of the anatomic variation of SN, the electrophysiological findings are variable. It should be considered to interpret the location of the PN lesion.