• The Journal of the Acoustical Society of Korea
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• v.24 no.5
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• pp.248-254
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• 2005

In this Paper, the structure of a split bandwidth wideband speech coder and its highband coder for tone qualify elevation are Proposed. The lowband and highband by the split bandwidth method are encoded independently applying the G.729E and MLT (Modulated Lapped Transform) residual model. In the highband structure which is encoded by low bit rate of 4kbps, the MLT residual signals are distinguished to voice and unvoice signal . The voice signals are applied to MLT peak picking method by lowband pitch period. Because transformed MLT residual signals are represented by periodic signal that have periodic peak. The unvoice signals are applied to MLT which linear prediction spectral response is added and do vector quantization. Performance for proposed 15.8kbps wideband speech coder was verified through subjective listening test.

• Archives of Pharmacal Research
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• v.22 no.2
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• pp.143-150
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• 1999

melatonin (MLT), N-acetyl-5-methoxytryptamine, is mainly secreted by the pineal gland. The ultraviolet (UV), infrared (IR) and 1H-NMR spectra of irradiated and non-irradiated MLT were measured, and phototoxicity tests of MLT, anthracence (positive control) and sodium lauryl sulfate (SLS, negative control) were performed. The methods employed include both in vitro test such as MTS assay using the human fibroblast cell and yeast growth inhibition assay using Candida albicans and in vivo method using the skin of guinea pig. UV absorption spectra and 1H-NMR spectra of MLT were changed by UVA (365 nm, 15 J/$\textrm{cm}^2$), but IR spectra of MLT were not changed. The fifty percent inhibitory concentration (IC50) ratio (UV-/UV+) of MLT was 10. The inhibition zone of irradiated-paper disks treated with MLT was not observed. According to the results of histophathological examination, no pathologic lesion was observed in the non-irradiated group, but slight degeneration of keratinocytes in the epidermis, homorrhage and vasodilation in dermis were observed in the irradiated group. These results indicated that the molecular structure of MLT is altered by UVA to unidentified photoproducts and a moderate phototoxicity of MLT is predicted.

• Journal of the Korean Society of Industry Convergence
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• v.19 no.3
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• pp.133-143
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• 2016

The objective in here is to find the density, stiffness, and strength of truss-wall rectangular (TWR) model which is combined with lattice truss (MLT) inside space. The TWR unit-cell model is defined as a unit cell originated from a solid-wall rectangular (SWR) model and it has an empty space inside. Thus, the empty space inside of the TWR is filled with lattice truss model defined as TWR-MLT. The ideal solutions derived of TWR-MLT are based on TWR with MLT model and it has developed by Gibson-Ashby's theory. To validate the ideal solutions of the TWR-MLT, ABAQUS software is applied to predict the density, strength, and stiffness, and then each of them are compared with the Gibson-Ashby's ideal solution as a log-log scale. Applied material property is stainless steel 304 because of cost effectiveness and easy to get around. For the analysis, SWR and TWR-MLT models are 1mm, 2mm, and 3mm truss diameter separately within a fixed 20mm opening width. In conclusion, the relative Young's modulus and relative yield strength of the TWR-MLT unit model is reasonably matched to the ideal expectations of the Gibson-Ashby's theory. In nearby future, TWR-MLT model can be verified by advanced technologies such as 3D printing skills.t.

• Toxicological Research
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• v.15 no.1
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• pp.39-45
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• 1999

To investigate the preventive effects of melatonin (MLT) on the immunotoxicity of cadmium acetate[Cd(AC)2] in ICR mice, Mlt(10,50mg/kg as cadmium) were orally administered to mice once a day (5:00, PM) for 28 consecutive days. Cadmium(Cd) test solution was also administered at 25mg/kg of cadmium through the same route 2hr after administration of MLT daily, Mice were immunized and challenged with sheep red blood cells (SRBC). Immune functions evaluated were delayed type hypersensitivity (DTH) response, mitogenic response, and flow cytometry analysis. The results of these studies were summarized as follows ; DTH response was abnormally increased in mice treated with Cd alone. DTH response was normally depressed in mice treated with Cd plus MLT along with the increase of MLT doses. The mitogenic response of splenic T cell to Con A and that of B cells to LPS was remarkably increased by MLT treatment as compared with treatment of Cd alone In case of CD 8+ cells, the slight increase was observed in MLT treatment. Splenic T cells and B cells were significantly increased by MLT treatment as compared with treatment with Cd alone. These results suggest that MLT has significant preventive effects on the immunotoxic status induced by Cd exposure.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.939-942
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• 2001

본 논문에서는 ITU-T G.723.1, G.729 부호화기와 MLT(Modulated Lapped Transform) 방법을 이용한 광대역 음성 부호화방법을 제안한다. 제안된 광대역 음성부호화 방법은 16 kHz로 샘플링된 입력신호를 QMF(Quadrature Mirror Filter)사용하여 저대역과 고대역으로 나누며, 각 대역은 8 kHz의 샘플링을 갖는 협대역 음성 신호로 변환된다. 고대역은 MLT변환 후 벡터 양자화하며 또한 MLT를 사용한 ATC(Adaptive Transform Coding)방법을 적용하여 표현하며 저대역은 G.723.1과 G.729 부호화기를 사용한다. 설계된 광대역 음성부호화기의 성능을 평가하기 위하여 MOS (Mean Opinion score)실험을 수행하였다. MOS 실험을 통해 16 kbps G.729-MLT VQ방식이 G.722 56kbps 와 비슷한 음질을 나타내었다.

• The Journal of the Acoustical Society of Korea
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• v.24 no.7
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• pp.395-401
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• 2005

In this paper, the high-band codec for bandwidth scalable wideband speech codec is proposed. The wideband input speech signal is separated into low-band signal and high-band signal, and the low-band signal is encoded by the standard narrow-band speech codec and the high-band signal is encoded by the proposed codec. In the high-band codec. the signal is transformed into frequency domain by MLT on a subframe basis, and MLT coefficients are splitted into magnitude and sign for quantization. The magnitudes of MLT coefficients are arranged into several time-frequency bands and each band is quantized in 2D-DCT domain, where the low-band information is utilized for better performance. The sign of MLT coefficient is quantized based on a priority selection process with the weighting measurement. The objective and subjective performance of wideband speech codec including the proposed high-band codec is measured, and it is confirmed that the proposed codec has better performance than 32kbps G.722.1.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.96-97
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• 2015

본 논문에서는 MLT 멀티미디어 프레임워크를 이용하여 홍보동영상을 자동 합성하는 웹 기반 서비스 프레임워크 상에서의 연동 인터페이스를 개발한다. 소상공인 홍보영상 제작시스템은 일반 소상공인들의 업종 정보와 잠재고객 특성정보를 기반으로 사진이나 동영상을 입력하면 관련된 홍보동영상을 자동으로 출력하는 시스템이다. 인지도가 높고 기능이 다양한 상용 소프트웨어들이 다수 존재하지만 소상공인들이 쉽고 저렴하게 사용할 수 있는 시스템 구성을 위해 본 논문에서는 공개소스 프로젝트인 MLT 멀티미디어 프레임워크를 사용한다. LGPL에 따라 개발 중인 MLT는 멀티미디어 콘텐츠들을 쉽게 조합하고 표시하는 필수 기능들을 제공하며 플러그인 구조를 채용하여 신규기능 탑재 및 효과추가도 가능하다. 하지만 MLT는 영상생성에 필요한 저수준 기능들을 주로 제공하므로 상위 계층에서 입력된 정보를 반영하여 홍보영상을 만드는 시스템 구성을 위해서는 상위 모듈들과의 연동 인터페이스의 설계 및 구현이 필요하다. 따라서 본 논문에서는 홍보전략 및 홍보의도와 같은 상위수준의 정보를 고려하여 MLT로 동영상을 실제 합성할 수 있도록 하는 계층화된 연동 구조를 제안한다.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.809-812
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• 2001

본 논문에서는 AMR(Adaptive Multi-Rate)과 MLT (Modulated Lapped Transform) 벡터 양자화 방법을 이용하여 광대역 음성부호화기를 설계하였다. 제안한 음성부호화 알고리즘은 split-band 구조를 가지고 있으며 16kHz로 샘플링 된 신호를 입력받아 QMF 필터에 의해 두 개의 대역으로 나누어, 각각 8kHz 샘플링 신호로 변환시킨 후 저대역(0Hz-3400Hz)의 신호와 고대역(3400Hz -7000Hz)의 신호로 나누어 각각 부호화한다. 나누어진 두 개의 협대역 음성신호는 AMR(Adaptive Multi-Rate)부호화기와 MLT (Modulated Lapped Transform)벡터 양자화 방법을 사용하여 각각 부호화되어 전송된다. 수신단에서는 각 대역을 AMR과 IMLT(Inverse MLT) 벡터 양자화 방법으로 역부호화하여 음성신호를 합성한다. 제안한 음성부호화기는 20.2kbps에서 12.15kbps까지의 다전송률로 동작된다. 설계된 광대역 음성부호화기는 MOS시험 결과로부터 G.722의 56 kbps 음성이 설계된 코더의 20.2 kbps와 비슷한 음질을 갖음을 확인할 수 있었다.

• Journal of Veterinary Clinics
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• v.18 no.4
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• pp.374-379
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• 2001

These studies were performed to investigate the effect of antioxidants, melatonin (MLT) and ascorbic acid (AA), on the diabetic complications. In the experiment, twenty-four Sprague Dawley rats were divided into four groups; Group 1: no treatment (control) (n=6), Group 2: Streptozotocin (STZ; 65 mg/kg b.w. ip) treatment (n=6), Group 3: MLT (10 mg/kg b.w. ip) treatment (n=6), Group 4: ascorbic acid (AA: 40 mg/kg b.w.ip) treatment (n=6). Rats were sacrificed and collected designated samples (blood, kidney, pancreas) at the 21 days after antioxidant treatment (the 8th week after STZ injection). There was no significant change of body weight during the experiment period in the all groups. The concentration of blood glucose was decreased below 200 mg/dl in MLT. The concentration of HbA$_1$c level was decreased significantly in MLT (7.3$\pm$0.66%) compared with STZ (15.1$\pm$1.58%) (p<0.01). No significant change of SOD activity in the RBC and kidney was found in the all groups. In the pancreas, MLT (1.42$\pm$0.17 U/ml) and AA(1.65$\pm$0.16 U/ml) decreased SOD activity compared with STZ (4.10$\pm$0.27 U/ml). However, there was no significant difference among MLT and AA. The level of malondialdehyde(MDA) as an indicator of lipid peroxydation was decreased in MLT compared with STZ in the plasma, kidney and pancreas(p<0.01). These findings suggest that melatonin could prevent the complications of diabetes mellitus.

• The Journal of the Acoustical Society of Korea
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• v.22 no.6
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• pp.425-433
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• 2003

Acoustic Echo Canceller (AEC) is a signal processing system for removing unwanted echo signals in teleconference and hands-free communication. Least mean square (LMS) algorithm is one of the adaptive echo cancellation algorithms and it has been most attractive because of its simplicity and robustness. However, the convergence properties of the LMS algorithm degrade with highly correlated input signals such as speech. For this reason, transform-domain adaptive filtering algorithm was introduced to decorrelate the colored input samples by using the orthogonal transform matrix such as DCT, DFT and then LMS adaptive filtering process is applied. In this paper, we propose a MLT domain adaptive echo canceller base on the MLT (Modulated lapped Transform) orthogonal transform matrix. The proposed algorithm achieves high decorrelation efficiency and fast convergence speed via modulated lapped transform of size 2NXN instead of NXN unitary transform such as DCT, DFT, Hadamad and it is applied to the acoustical echo cancellation system. Form the computer simulation with both synthesis and real speech, the proposed MLT domain adaptive echo canceller shows approximately twice faster convergence speed and 20∼30 ㏈ ERLE improvements over the DCT frequency domain acoustic echo cancellation system.