• 한국세라믹학회지
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• 제44권5호
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• pp.179-183
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• 2007

BCB $Resin-BaNd_2Ti_4O_{12}$(BNT) composites with BNT contents were prepared by tape casting method and epoxy resin-BNT composites were prepared by using heating press. Their dielectric properties and microstructures were investigated. The dielectric properties such as dielectric constant and dielectric loss at 1 MHz for epoxy resin-BNT composites and BCB resin-BNT composites are improved with an increase of BNT volume fraction. The dielectric constant of the Epoxy-BNT composite increased from 5.9 to 7.8 as the volume fraction of BNT increased from 15 to 25. The dielectric constant of the BCB-BNT composite increased from 9.1 to 15.5 as the volume fraction of BNT increased from 30 to 50. The dielectric behavior of BCB-BNT system can be explained by Lichtenecker's equation. The dielectric constant of epoxy resin-BNT composite is smaller than that of BCB resin-BNT composite. These results are considered to be related with the dispersion of BNT filler in polymer matrix from the result of SEM photograph.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1242_1243
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• 2009

The heterolayered BT-BNT thick films were fabricated by screen printing techniques on alumina substrates electrodes with Pt. We report the improved ferroelectric and dielectric properties in the heterolayered teteragonal/rhombohedral structure composed of the BT and the BNT thick films. We investigated the effects of deposition conditions on the structural and electrical properties of the heterolayered BT-BNT thick films. The dielectric properties of the heterolayered BT-BNT thick films were superior to those of single composition BNT, and those values for the heterolayered BT-BNT thick films were 1455, 0.025 and $12.63{\mu}C/cm^2$.

• 한국전기전자재료학회논문지
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• 제24권7호
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• pp.547-553
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• 2011

We investigated the dielectric and mechanical properties of ceramic polymer composite xBNT - (1-x)LCP (x= 0, 10, 20, 30, 40 vol.%). The disk shaped BNT ($BaNd_2Ti_4O_{12}$) - LCP (liquid crystal polymer) composite samples were prepared by compression molding method. With increasing the BNT content in composites from 10 to 40 vol.%, the dielectric constant increased but the dielectric loss as well as bending strength of composites reduced. These composites were well described with modified Lichtenecker's model having k = 0.392 and 0.303 for the first and second ball milled BNT filled composites, which means that the BNT filler in composites are well dispersed. The dielectric constant of the composite comprised of the second milled BNT ($D_{50}$ = 1.39 um) was higher that of the composite of the first milled BNT ($D_{50}$= 2.45 um), which seems to be related with the different particle size and dispersion of BNT fillers in LCP matrix. The bending strength of the composite containing the second milled BNT was superior to that of the composite of the first milled BNT.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.298-298
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• 2010

In this study, both structural, dielectric properties of the NKN-0.94BNT-0.06BT ceramics were investigated. All samples of the NKN-0.94BNT-0.06BT ceramics were fabricated by conventional mixed oxide method with Pt electrodes. We report the improved electrical properties in the perovskite structure composed of the NKN, BNT and the BT ceramics. We investigated the effects of NKN, BT on the structural and electrical properties of the NKN-0.94BNT-0.06BT ceramics. The dielectric and structural properties of the NKN-0.94BNT-0.06BT ceramics were superior to those of single composition NKN, NKN-BNT and those values for the NKN-0.94BNT-0.06BT ceramics were 1455, 0.025 and $29.04{\mu}C/cm^2$.

• 말소리와 음성과학
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• 제4권3호
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• pp.137-142
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• 2012

The aim of this study is to investigate the usefulness of the multiple-choice name matching test (MC-NMT) in adults with aphasia by comparing the Korean version of the Boston Naming Test (K-BNT) and subsets of the Korean version of the Western Aphasia Battery (K-WAB). Thirty-nine patients who suffer from aphasia participated in the study. All patients were examined by the K-BNT, MC-NMT and K-WAB. The MC-NMT consisted of the 30 original BNT object stimuli which were presented with four response choices (written words) with similar frequency, including one correct and three incorrect responses. Cards containing the drawings were presented to the patient one at time. An item was passed if the patient chose the correct response within 10 seconds. We subdivided two groups into a total group and a low K-BNT group (at and below 15 points). We evaluated the correlation between the K-BNT, MC-NMT score and production, naming, repetition, comprehension, reading and writing scores in subsets of the K-WAB. There was a highly positive correlation between the K-BNT score and naming score of the K-WAB in total patients. However, the MC-NMT was highly correlated with reading scores in the K-WAB. In low score K-BNT patients, the K-BNT strongly correlated with production, naming and repetition scores of the K-WAB. These findings mean that K-BNT reflects motor language function. However, the MC-NMT was strong correlated comprehension, reading and writing of the K-WAB. This finding reflects sensory language function. We suggest that the combination of K-BNT and newly developed MC-NMT will be useful to evaluate speech functions in aphasic patients.

• 한국콘텐츠학회논문지
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• 제13권12호
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• pp.321-327
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• 2013

이름대기 능력의 손상은 신경학적 질환을 지닌 환자뿐만 아니라, 정상적인 노화과정에 있는 노인에게서도 빈번하게 관찰된다. 이름대기 능력을 평가하기 위해 가장 널리 사용되고 있는 한국판 보스톤 이름대기 검사(Korean version-the Boston Naming Test, K-BNT)는 60문항으로 구성되어 있다. 일반노인들은 노화에 따른 주의력 감소로 인하여 검사 소요시간이 길면 검사에 대한 집중이 어려워지므로, 검사 결과에 대한 타당도 및 신뢰도를 확보하기 위해서는 문항축소가 바람직하다. 본 연구의 목적은 '문항반응이론(Item Response Theory)'을 적용하여, 60개 문항의 K-BNT를 일반노년층의 이름대기 능력을 가장 잘 평가할 수 있는 15개 문항의 검사(즉, K-BNT-15)를 개발하는 것이었다. 이를 위하여, 일반노인 175명을 대상으로 라쉬분석을 실시하여, 문항적합도, 성별 차이, 문항난이도 등을 평가하였다. K-BNT-15의 실시 결과, 일반 노년층은 10년 단위로 수행력이 감소하였고, 경도인지장애(mild cognitive impairment, MCI) 환자는 일반 노년층에 비해 유의하게 낮은 수행력을 보였다. 본 연구에서는 언어 평가도구의 단축형 개발 시, 특정 집단의 언어적 능력과 문항의 응답 결과의 관계를 규명하여 그 집단에게 적합한 문항을 선별할 수 있다는 점에서 문항반응이론이 유용함을 보여주었다. 또한, K-BNT-15가 노화에 따른 대면이름대기 감소 및 환자군과의 차이를 잘 보여주는 검사임을 검증하였다.

• 인지과학
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• 제11권2호
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• pp.59-68
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• 2000

본 연구는 한국판 보스톤 이름대기 검사(Korean-Boston Naming Test: K-BNT)의 실험적 단축형을 개발하여 그 규준을 제시하고 검사의 임상적 유용성을 살펴보고자 하였다. 서울-경기 지역에 거주하는 만 55∼84세의 건강한 장노년 인구를 대상으로 수행 자료가 수집되었다. 검사 수행에 미치는 인구 통계학적 변인들의 효과를 분석한 결과 교육과 연령이 유의미한 요인으로 확인되어 그에 따라 규준이 개발되었다. 두 개의 연령 수준(만 55∼64세, 만 65∼84세)과 각 연령에 따라 다시 두 개의 학력 수준(6년 이하, 7년 이상)으로 구분되어 총 4개의 하위 규준이 만들어졌다. 검사에 대한 정상 노인의 수행을 알츠하이머형 치매(Dementia of the Alzheimers type: DAT) 환자들의 수행과 비교했을 때 두 집단간 유의미한 수행 차이를 보여주었다(F(1, 158)= 23,216, p < .0001). K-BNT의 실험적 단축형의 노인 규준 자료는 임상 장면에서 치매 및 여러 중추신경계 손상 환자들의 이름대기 능력을 신속하게 판별하는데 기여하리라 기대된다.

• 한국전기전자재료학회논문지
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• 제23권10호
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• pp.771-775
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• 2010

In this study, piezoelectric and dielectric properties of the $(Na_{0.5}K_{0.5})NbO_3-(1-x)(Bi_{0.5}Na_{0.5})TiO_3-xBaTiO_3$ [NKN-(1-x)BNT-xBT] ceramics were investigated. The lead-free NKN-(1-x)BNT-xBT ceramics were fabricated by a conventional mixed oxide method. The results indicate that the addition of $BaTiO_3$ significantly influences the sintering, microstructure, phase transition and electrical properties of NKN-BNT ceramics. A gradual change in the piezoelectric and dielectric properties was observed with the increase of BT contents. The dielectric constant, piezoelectric constant ($d_{33}$) and electromechanical coupling factor ($k_p$) increased at the morphotropic phase boundary (MPB). The $d_{33}$=184 pC/N, $k_p$=0.38, dielectric constant=1455 with dielectric loss value of less than 1% were obtained for the NKN-0.95BNT-0.05BT ceramics sintered at $1150^{\circ}C$ for 2h. These results demonstrate that the NKN-(1-x)BNT-xBT ceramics is an attractive candidate for lead-free piezoelectric materials.

• 한국결정성장학회지
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• 제17권6호
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• pp.251-255
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• 2007

높은 유전상수와 낮은 유전손실을 가지는 $(1-x)BCB-xBNT(BaNd_2Ti_4O_{12})$ (x=20, 30, 40, 50 vol%) 복합 재료를 제작하였다. 제작된 film의 유전 상수와 유전 손실은 1 MHz에서 측정되었고, DSC와 같은 열분석을 통하여 그 경화거동을 관찰하고, BNT의 함량과 film의 경화 거동이 유전특성에 어떠한 영향을 미치는지에 대하여 조사하였다. 충진제로 사용된 BNT가 $20{\sim}50vol%$까지 증가함에 따라 그 복합체의 유전상수는 증가, 유전 손실($tan{\delta}$)은 감소하였고, BCB-BNT 복합체의 유전 상수와 유전 손실($tan{\delta}$)은 경화 반응에 거의 영향을 받지 않는다. 그러나 경화 온도가 증가함에 따라 TCC(Temperature Characteristics of Coefficient)가 감소하는 것으로 복합체의 경화는 $250^{\circ}C$ 이상에서 가장 안정하다는 것을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1324_1325
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• 2009

The heterolayered $BaTiO_3/(Bi_{0.5}Na_{0.5})TiO_3$ thick films were fabricated by screen printing techniques on alumina substrates electrodes with Pt. We report the improved ferroelectric properties in the heterolayered teteragonal/rhombohedral structure composed of the $BaTiO_3$ and the $(Bi_{0.5}Na_{0.5})TiO_3$ thick films. We investigated the effects of deposition conditions on the structural and electrical properties of the heterolayered BNT/BT thick films. The structural and electrical properties of the heterolayered BNT/BT thick films were studied. All PZT heterolayered thin films show dense and homogeneous structure without the presence of the rosette structure. The dielectric constant, loss and remanent polarization oft heheterolayered BNT/BT thick films were superior to those of single composition $BaTiO_3$ and $(Bi_{1/2}Na_{1/2})TiO_3$, and those values for the heterolayered BNT/BT thick films sintered at $1100^{\circ}C$ were 916, 0.79 and $12.63{\mu}C/cm^2$.