• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제20회 춘계학술대회 논문집
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• pp.91-93
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• 2003

A comprehensive numerical study is carried out to investigate for the understanding of the flow evolution and flame development in a supersonic combustor with normal injection of ncumally injecting hydrogen in airsupersonic flows. The formulation treats the complete conservation equations of mass, momentum, energy, and species concentration for a multi-component chemically reacting system. For the numerical simulation of supersonic combustion, multi-species Navier-Stokes equations and detailed chemistry of H2-Air is considered. It also accommodates a finite-rate chemical kinetics mechanism of hydrogen-air combustion GRI-Mech. 2.11[1], which consists of nine species and twenty-five reaction steps. Turbulence closure is achieved by means of a k-two-equation model (2). The governing equations are spatially discretized using a finite-volume approach, and temporally integrated by means of a second-order accurate implicit scheme (3-5).The supersonic combustor consists of a flat channel of 10 cm height and a fuel-injection slit of 0.1 cm width located at 10 cm downstream of the inlet. A cavity of 5 cm height and 20 cm width is installed at 15 cm downstream of the injection slit. A total of 936160 grids are used for the main-combustor flow passage, and 159161 grids for the cavity. The grids are clustered in the flow direction near the fuel injector and cavity, as well as in the vertical direction near the bottom wall. The no-slip and adiabatic conditions are assumed throughout the entire wall boundary. As a specific example, the inflow Mach number is assumed to be 3, and the temperature and pressure are 600 K and 0.1 MPa, respectively. Gaseous hydrogen at a temperature of 151.5 K is injected normal to the wall from a choked injector.A series of calculations were carried out by varying the fuel injection pressure from 0.5 to 1.5MPa. This amounts to changing the fuel mass flow rate or the overall equivalence ratio for different operating regimes. Figure 1 shows the instantaneous temperature fields in the supersonic combustor at four different conditions. The dark blue region represents the hot burned gases. At the fuel injection pressure of 0.5 MPa, the flame is stably anchored, but the flow field exhibits a high-amplitude oscillation. At the fuel injection pressure of 1.0 MPa, the Mach reflection occurs ahead of the injector. The interaction between the incoming air and the injection flow becomes much more complex, and the fuel/air mixing is strongly enhanced. The Mach reflection oscillates and results in a strong fluctuation in the combustor wall pressure. At the fuel injection pressure of 1.5MPa, the flow inside the combustor becomes nearly choked and the Mach reflection is displaced forward. The leading shock wave moves slowly toward the inlet, and eventually causes the combustor-upstart due to the thermal choking. The cavity appears to play a secondary role in driving the flow unsteadiness, in spite of its influence on the fuel/air mixing and flame evolution. Further investigation is necessary on this issue. The present study features detailed resolution of the flow and flame dynamics in the combustor, which was not typically available in most of the previous works. In particular, the oscillatory flow characteristics are captured at a scale sufficient to identify the underlying physical mechanisms. Much of the flow unsteadiness is not related to the cavity, but rather to the intrinsic unsteadiness in the flowfield, as also shown experimentally by Ben-Yakar et al. [6], The interactions between the unsteady flow and flame evolution may cause a large excursion of flow oscillation. The work appears to be the first of its kind in the numerical study of combustion oscillations in a supersonic combustor, although a similar phenomenon was previously reported experimentally. A more comprehensive discussion will be given in the final paper presented at the colloquium.

• 대한한의진단학회지
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• 제10권1호
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• pp.109-140
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• 2006

Background: In practicing qigong, People must achieve three Points : adjust their Posture, control their breathing and have a peace of mind. That is, Cho-Sin [調身] , Cho-Sik [調息] , Cho-Sim [調心] . Slow respiration is the important pattern of respiration to improve the human health. However, unsuitable breathing training have been occurred to mental disorder such as insomnia, anorexia etc. So, we think that the breathing training to consider the individual variations are desired. Objectives: We performed this study to examine the physiological effects of controlled respiration on the normal range of frequency domain electroencephalogram(EEC) in healthy subjects Also, to study examine individual variations according to the physiological effects between controlled respiration and Han-Yeol [寒熱] , respiration period, gender and age-related groups on the EEC in healthy subjects. Methods: When the subjects controlled the time of breathing (inspiration and expiration time) consciously, compared with natural respiration, and that their physiological phenomena are measured by EEC. In this research we used breathing time as in a qigong training (The Six-Word Excise) and observed physiological phenomena of the controlled natural respiration period with the ratio of seven to three(longer inspiration) and three to seven(longer expiration) . We determined, heat-cold score by Han-Yeol [寒熱] questionnaire, average of natural respiration period, according to decade, EEC of 140 healthy subjects (14 to 68 years old; 38 males, 102 females) by means of alpha, beta spectral relative power. Results: 1) In Controlled respiration compared with the natural respiration, ${\alpha}\;I\;(Fp2)\;and\;{\beta}$ I (Fpl, Fp2, F3, F4) decreased on the EEC. 2) In controlled respiration compared with the natural respiration, ${\beta}$ I (Fpl, Fp2, F3, F4) increased with cold group, ${\alpha}/{\beta}$(F3) decreased with heat group, ${\alpha}$ I (Fp2)increased with cold group in longer inspiration. But by means of compound effects, ${\alpha}$ II(F3) increased with cold group in longer inspiration, the other side ${\alpha}$ I (F3) decreased with heat group in controlled respiration on the EEC. 3) In controlled respiration compared with the natural respiration, ${\alpha}$ I (Fp2) decreased with decreased-respiratory-rate(D.R.R.) group, ${\beta}$ I (Fpl, Fp2, F3, F4) increased with D.R.R. and D.R.R. groups, ${\alpha}/{\beta}$(F3) decreased with D.R.R. group. But by means of compound effects, in controlled respiration compared with the natural respiration, ${\alpha}/{\beta}$(F3) decreased with D.R.R. group on the EEG. 4) In controlled respiration compared with the natural respiration, ${\beta}$ I (Fpl, F3, F4) increased with female cup, ${\beta}$ I (Fp2) increased with male and female groups, ${\alpha}/{\beta}$(F3) decreased with male group. But by means of compound effects, in controlled respiration compared with the natural respiration, ${\alpha}$ I (Fp2) increased with female group on the EEC. 5) Compared with the natural respiration, in longer expiration ${\alpha}$ I (Fp2) increased in their forties group, in longer inspiration ${\alpha}$ I (Fp2) increased in their fifties group. But by means of compound effects, in controlled respiration compared with the natural respiration, ${\beta}$ I (Fpl) decreased in teens group on the EEG.

• Journal of Chest Surgery
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• 제25권1호
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• pp.1-16
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• 1992

The quantitatively measured local myocardial perfusion rates with microspheres are used as an objective indicator of even distribution of cardioplegic solution, and the efficacy of the retrograde right atrial route of cardioplegia is evaluated in hearts with various levels of coronary arterial obstruction. After initial antegrade cardioplegia under the median sternotomy and aortic cannulation, 60 hearts from anesthetized New Zealand white rabbits are divided in random order as normal group [ligated left main coronary artery ; MA, MR] and diagonal group [ligated proximal diagonal artery ; LA, LR]. Half of each group [N=10] are perfused with antegrade cardioplegia[A] under the pressure of 100 cmH2O and the other half with retrograde right atrial route[R] under the pressure of 60 cmH2O[St. Thomas cardioplegic solution mixed with measured amount of microspheres]. The myocardium is subdivided into segments as A[atria], RV[right ventricle]. S[septum], LV[normally perfused left ventricular free wall], ROI[ischemic myocardium of left ventricular free wall]. LV and RQI are further divided into N[subendocardium] and P[subepicardium]. The resulting local myocardial perfusion rates and N /P of each group are compared with Wilcoxon rank sum test. The weight of the hearts is 5.94$\pm$0.66g, and there are no statistically significant dif-ferences[p>0.05, ANOVA] between six compared group. The mean flow rate[F: ml /g / min] of MR group is comparable with MA group[p>0.05], but in N and L group, there are significantly depressed F with right atrial route of cardioplegia, which means elevated perfusion resistance with this route. In spite of no significant differences in delivered doses of microsphere[DEL] between compared groups[p>0.05, ANOVA], there are significantly depressed REC and NF in hearts with right atrial cardioplegia which suggests increased requirement of cardioplegic solution with this route. The interventricular septum shows poor perfusion with right atrial route of cardioplegia without obstruction of supplying coronary arteries. But, with obstruction of coronary artery supplying septum as in M group, the flow rate is superior with right atrial route of infusion. The left ventricular free wall perfusion rates of every RQI with R route are superior to that of A route[p<0.05]. But, in LV segments, there are unfavorable effects of right atrial cardioplegia in L group, although the subendocardial perfusion is well maintained in N group. The LV free wall of left main group shows depressed perfusion rates with antegrade route as compared with RQI segments of diagonal group. But, by contraries, there are increased perfusion rates and superior N /P ratio with retrograde right atrial route. It implies more effective perfusion with right atrial route of cardioplegia in more proximal coronary arterial obstruction[i.e., M group as compared with L group]. As a conclusion, all region of ischemia have superior perfusion rates with right atrial car-dioplegia as compared with antegrade route, and especially excellent results can be obtained in hearts with more proximal obstruction of coronary arteries which would otherwise result in more severe ischemic damage. But, the depressed perfusion rates of the segments with normal coronary artery in hearts with coronary arterial obstruction may be a problem of concern with right atrial cardioplegia and needs solution.

• Journal of Yeungnam Medical Science
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• 제12권2호
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• pp.319-330
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• 1995

임신시 발생하는 인슐린 저항성과 인슐린 분비 증가의 기전을 규명하기 위하여 Sprague-Dawley 종 암컷 흰쥐를 이용하여 정맥당부하 검사와 호르몬 및 지방 대사물질과 조직에서의 인슐린 수용체 결합, 당원질 합성효소를 분석한 결과를 요약하면 다음과 같다. 정맥당부하검사에서 임신군에서 전체적인 곡선이 대조군에 비하여 아래에 위치하였다. 그러나 당부하시 인슐린 분비는 현저히 증가하였으며 혈당에 대한 비(${\mu}U/mg$)로 비교하여 임신군에서 $56.9{\pm}8.9$였고 대조군에서 $23.6{\pm}2.8$로서 인슐린 저항성을 확인할 수 있었다. 인슐린 분비반응의 증가는 태반 호르몬인 progesterone의 증가와 강한 상관관계를 나타내었다. 당부하검사후 당원질 (mg/100mg tissue)은 골격근(soleus)에서는 임신군과 대조군간에 유의한 차이가 없었으나 간조직에서는 임신군에서 $4.7{\pm}0.9$으로 대조군의 $9.9{\pm}1.3$에 비하여 통계적으로 유의하게 감소하였다. 당원질로 합성된 $^{14}C$-glucose의 활동도도 마찬가지로 골격근에서는 임신군과 대조군간에 유의한 차이가 없었으나 간조직에서는 현저한 감소를 보였다. 당원질 합성 효소(glycogen synthase)는 골격근에서는 대조군이 높았고 간장조직에서는 임신군이 높았으나 유의한 차이는 없었다. 당부하검사후 간장조직의 crude membrane에서의 인슐린-인슐린 수용체 결합반응에서는 두 군 사이에 유의한 차이가 없었다. 이상의 결과로 보아 정상임신흰쥐에서 인슐린 저항성이 발생하였으나 인슐린 분비의 현저한 증가로 내당능의 감소는 나타나지 않았으며 인슐린의 분비증가는 progesterone의 증가와 상관관계가 있었다. 인슐린 저항성은 간에서 가장 현저하게 나타났으며 그 원인은 인슐린 수용체의 결합과정보다는 수용체 전 과정이거나 수용체 후 과정일 것으로 추정된다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 추계 학술논문 발표대회
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• pp.109-113
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• 2007

This paper introduces a system, Simulation based Stochastic Markup Estimation System (S2ME), for estimating optimum markup for a project. The system was designed and implemented to better represent the real world system involved in construction bidding. The findings obtained from the analysis of existing assumptions used in the previous quantitative markup estimation methods were incorporated to improve the accuracy and predictability of the S2ME. The existing methods has four categories of assumption as follows; (1) The number of competitors and who is the competitors are known, (2) A typical competitor, who is fictitious, is assumed for easy computation, (3) the ratio of bid price against cost estimate (B/C) is assumed to follow normal distribution, (4) The deterministic output obtained from the probabilistic equation of existing models is assumed to be acceptable. However, these assumptions compromise the accuracy of prediction. In practice, the bidding patterns of the bidders are randomized in competitive bidding. To complement the lack of accuracy contributed by these assumptions, bidding project was randomly selected from the pool of bidding database in the simulation experiment. The probability to win the bid in the competitive bidding was computed using the profile of the competitors appeared in the selected bidding project record. The expected profit and probability to win the bid was calculated by selecting a bidding record randomly in an iteration of the simulation experiment under the assumption that the bidding pattern retained in historical bidding DB manifest revival. The existing computation, which is handled by means of deterministic procedure, were converted into stochastic model using simulation modeling and analysis technique as follows; (1) estimating the probability distribution functions of competitors' B/C which were obtained from historical bidding DB, (2) analyzing the sensitivity against the increment of markup using normal distribution and actual probability distribution estimated by distribution fitting, (3) estimating the maximum expected profit and optimum markup range. In the case study, the best fitted probability distribution function was estimated using the historical bidding DB retaining the competitors' bidding behavior so that the reliability was improved by estimating the output obtained from simulation experiment.

• 한국컴퓨터정보학회논문지
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• 제18권8호
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• pp.65-75
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• 2013

본 논문에서는 깊이 영상만을 이용하여 손 영역 추적 및 손 끝점 검출 방법을 제안한다. 조명 조건의 영향을 제거하고 빠르고 안정적인 정보 획득을 위해 깊이 정보만을 이용하는 추적 방법을 제안하고, 영역 확장 방법을 통해 추적 과정 중에 발생할 수 있는 오류에 대한 판단 방법과 다양한 제스처 인식에 응용이 가능한 손 끝점 검출 방법을 제안한다. 먼저 추적점을 찾기 위해 중심점 전이 과정을 통해 최근접점을 찾고 그 점으로부터 영역 확장을 통해 손 영역과 경계선을 검출한다. 그리고 영역 확장을 통해 획득한 무효경계선의 비율을 이용하여 추적영역에 대한 신뢰도를 계산함으로써 정상 추적 여부를 판단한다. 정상적인 추적인 경우, 검출된 손 영역으로부터 윤곽선을 추출하고 곡률 및 RANSAC, 컨벡스 헐(Convex-Hull)을 이용하여 손 끝점을 검출한다. 마지막으로 성능 검증을 위해 다양한 상황에 따른 정량적, 정성적 분석을 통해 제안하는 추적 및 손 끝점 검출 알고리즘의 효율성을 입증한다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 제17회 워크샵 및 추계학술대회
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• pp.561-566
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• 2005

Polycrystalline silicon films were deposited using hot wire CVD (HWCVD). The deposition of silicon thin films was approached by the theory of charged clusters (TCC). The TCC states that thin films grow by self-assembly of charged clusters or nanoparticles that have nucleated in the gas phase during the normal thin film process. Negatively charged clusters of a few nanometer in size were captured on a transmission electron microscopy (TEM) grid and observed by TEM. The negatively charged clusters are believed to have been generated by ion-induced nucleation on negative ions, which are produced by negative surface ionization on a tungsten hot wire. The electric current on the substrate carried by the negatively charged clusters during deposition was measured to be approximately $-2{\mu}A/cm^2$. Silicon thin films were deposited at different $SiH_4$ and $H_2$ gas mixtures and filament temperatures. The crystalline volume fraction, grain size and the growth rate of the films were measured by Raman spectroscopy, X-ray diffraction and scanning electron microscopy. The deposit ion behavior of the si1icon thin films was related to properties of the charged clusters, which were in turn controlled by the process conditions. In order to verify the effect of the charged clusters on the growth behavior, three different electric biases of -200 V, 0 V and +25 V were applied to the substrate during the process, The deposition rate at an applied bias of +25 V was greater than that at 0 V and -200 V, which means that the si1icon film deposition was the result of the deposit ion of charged clusters generated in the gas phase. The working pressures had a large effect on the growth rate dependency on the bias appled to the substrate, which indicates that pressure affects the charging ratio of neutral to negatively charged clusters. These results suggest that polycrystalline silicon thin films with high crystalline volume fraction and large grain size can be produced by control1ing the behavior of the charged clusters generated in the gas phase of a normal HWCVD reactor.

• Parasites, Hosts and Diseases
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• 제29권3호
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• pp.279-292
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• 1991

마우스에의 돼지회충(Ascaris strum) 또는 선모충(Trichinella spiralis) 감염이 sRBC에 대한 면역능에 미치는 영향을 조사한 다음 전처치로서 선모충을 감염시키거나 또는 cyclophosphamide를 투여하고 나서 돼지회충란을 경구투여하여 그 감염상태와 소장점막내 비만세포와의 관련성 그 리고 비특이 세포성 및 체액성 면역능을 함께 관찰하였다. 마우스에 1,000개의 돼지회충란을 경구투여한 바 지연형 과민반응과 로제트 형성능은 시일이 경과됨에 따라 점점 감소하기 시작하여 각각 5주, 6주에 최저치에 이른 다음 점점 상승하여 10주에 원상으로 복귀하였으며, 적현구 응집소가 및 용현소가는 점점 상승하여 3주에 최고치에 이른 다음 그 후 정상으로 복귀하였으며, 말초힐액내 호산구 및 소장접막내 비만세포 출현율은 각각 4주 및 2주에 최고치를 보였다. 한편, 유충은 1주후에 폐와 간으로부터 총 21.97%가 누수되었다. 마우스에 300마리의 선모충의 감염유충을 경구투여한 바 지연형 과민반응과 로제트 형성능은 시일이 경과 됨에 따라 점점 낮아져 각각 30일 및 21일에 전저치에 이른 다음 그 후부터 다소 높아지다가 70일 및 80일에 다시 일시적으로 낮아졌다. 그리고, 적현구 응집소가 및 용혈소가도 각각 21일 및 90일 에 다른 기보다 낮았으나, 말초혈액내 호산구 및 소장점막내 비만세포 출현율은 각각 40일째 및 14 일째에 다른 기보다 높았다. Cyclophosphamide를 400 mg/kg의 용량으로 마우스의 복륙 내에 투여한 바 체중이나 비장의 중량, 지연형 과민반응, 로제트 형성능, 적혈구 응집소가 및 용혈소가, 백현구 총수, 소장점막내 비만세포 출현율은 투여 후 1일에 비하여 5일에 현저하게 저하되었다가 10일에 다 시 증가하여 1일과 거의 비슷한 수준으로 복귀하였다. 말포혈액내 호산구 출현율은 시일이 경과함 에 따라 점점 낮아지는 경향이었다. 한편, 마우스의 복강 내에 cyclophosphamide를 투여한 다음 1일, 5일, 10일에 각각 1,000개의 감염성 돼지회충란을 투여하고 난 후 7일의 유충각수률은 1일 7.07%, 5일 14.94%, 10일 10.1%이었으며 대조군은 8.02%이었다 유모충을 마우스에 감작감염시키고 나서 각각 30일 및 70일 간격을 두고 감염성 돼지회충란을 도전감염시킨 바 참작감염후 37일과 도전감염후 7일의 시점에 있어서 지연형 과민반응과 로제트 형성능은 고도로 저하하였는데 반하여 소장점막내 비만세포 출현율은 고도로, 말초혈액내 호산구출현율, 적혈구 응집소가 및 용혈소가는 상당히 증가하였다. 이 시점에 있어서의 유충은 대조가 22.18% 회수되었는데 비하여 9.3%밖에 회수되지 않았다. 한편, 감작감염후 77일과 도전감염후 7일의 시점에 있어서 sRBC에 대한 면역능에 미치는 영향은 전자의 양상과 비슷하였는데 대조에 비하여 지연형 과민반응과 로제트 형성능이 현저하게 저하되었다. 이 시점에 있어서의 유충회수율은 대조가 10.5% 이었는데 비하여 8.3%이었다.

• 대한토목학회논문집
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• 제28권4A호
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• pp.537-548
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• 2008

최근 들어 비부착 강선을 이용한 프리스트레스트 콘크리트 구조물의 건설이 증가하고 있다. 그러나 극한거동 해석 시 단면 적합조건을 이용하는 내부 부착 강선과는 다르게 비부착 강선은 부재의 전체거동에 의해서 응력 증가량이 결정된다. 또한 외부 강선의 경우에는 편향부에서의 미끌림 효과와 강선의 편심 변화 효과 등이 발생하게 된다. 따라서 본 연구는 비부착 강선을 가지는 프리스트레스트 콘크리트(PSC) 보의 거동 특성을 평가하고 비부착 강선의 극한 응력을 구하기 위하여 지간길이/유효깊이, 콘크리트 압축강도, 철근비 및 기존 부착강선의 영향 등을 변수로 하여 정적 휨실험을 수행하여 비부착 강선 부재의 휨거동 특성을 얻었다. 실험결과에 의하면 균열하중, 철근 항복 하중 및 파괴하중의 경우, 콘크리트 강도보다는 철근비의 영향이 더 크게 나타났으며, 강도 측면에서는 고강도의 경우가 저강도의 경우보다 약간은 구조 성능이 우수하나, 큰 차이는 없는 것으로 나타났다. 또한 L/dp 값이 커질수록 훨씬 더 긴 구간의 연성 거동이 있는 것으로 나타났다. 이는 철근 항복 이후 비부착 강선의 기여가 상당히 크다는 것을 알 수 있었으며, ACI-318에서 제시하고 있는 비부착 강선의 극한 응력식은 실험 결과와 잘 일치하지 않으며, 경향성도 없는 것으로 나타났다. 실험결과 들을 분석하여 미끌림 현상이 없는 비부착 강선의 극한응력에 대한 예측식을 제안하였다. 제안된 예측식은 실험결과와 비교적 잘 일치하는 것으로 나타났으며, 미끌림 현상이 없는 비부착 강선의 극한 휨거동 평가, PSC 부재 해석 및 설계 시 본 연구에서 제안된 식은 유용한 기초가 될 것으로 사료된다.

• 재활복지공학회논문지
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• 제3권1호
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• pp.27-34
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• 2009

난청인의 청력 손실은 개인별로 다양하므로 기존의 대칭적으로 주파수 밴드별 청각 필터를 구현하는 방법은 다양한 형태의 난청인의 청력 손실을 적절하게 모사해주지 못한다. 각 중심주파수와 음성의 입력크기에 따라 청각 필터의 형태가 비대칭적으로 바뀌고 청력손실이 있는 난청인은 청력 손실에 따라 청각필터의 형태가 정상인들과는 다른 형태로 바뀌게 되며 음질에도 차이가 있다. 본 연구에서는 난청인의 난청 정도에 따라 변하는 비대칭 청각 특성을 잘 반영한 청각필터를 구현하여 몇 가지 실험을 통해 각 구현된 청각 필터의 성능을 객관적으로 평가하였다. 실험은 구현된 청각 필터를 통한 음성의 perceptual evaluation of speech quality (PESQ) 와 log likelihood ratio (LLR)를 사용하였으며 그 값을 통해 처리된 음성의 객관적인 음질과 왜곡정도를 평가 하였다. 청력 손실을 주었을 때 대칭과 비대칭 청각 필터사이의 PESQ 와 LLR 값을 실험해 본 결과 청각 필터 간의 큰 차이를 보였다. 위 실험 결과들로 대칭과 비대칭 청각 필터의 형태에 따라서 음성의 음질에 영향을 받는다는 것을 알 수 있었다. 특히, 난청이 있을 때 중심 주파수별 청각 필터의 비대칭적 형태 변화가 난청인이 받아들이는 음질에 영향이 있었다.