• 음성과학
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• 제8권4호
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• pp.45-58
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• 2001

Modulated components of a speech signal are frequently used for speech coding, speech recognition, and speech synthesis. Time-frequency representation (TFR) reveals some information about instantaneous frequency, instantaneous bandwidth and boundary of each component of the considering speech signal. In many cases, the extraction of AM-FM components corresponding to instantaneous frequencies is difficult since the Fourier spectra of the components with time-varying instantaneous frequency are overlapped each other in Fourier frequency domain. In this paper, an efficient method decomposing speech signal into AM-FM components is proposed. A variable bandwidth filter is developed for the decomposition of speech signals with time-varying instantaneous frequencies. The variable bandwidth filter can extract AM-FM components of a speech signal whose TFRs are not overlapped in timefrequency domain. Also, amplitude and instantaneous frequency of the decomposed components are estimated by using Hilbert transform.

• Journal of Pharmaceutical Investigation
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• 제30권4호
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• pp.267-271
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• 2000

The effect of cyclodextrins on the solubility and stability of aspalatone (acetylsalicylic acid maltol ester, AM, CAS 147249-33-0), which has been recently found to have an antithrombotic effect, was investigated. The addition of ${\beta}-cyclodextrin\;({\beta}-CD),\;dimethyl-{\beta}-cyclodextrin\;(DMCD)\;or\;2-hydroxypropyl-{\beta}-cyclodextrin\;(HPCD)$ to the aqueous solution increased the solubility of AM concentration-dependently. From the phase solubility diagram, stability constants for $AM-{\beta}-CD$, -DMCD or -HPCD complexes were calculated to be 43.1, 78.3 and $53.0\;M^{-1}$. The addition of ${\beta}-CD$, DMCD or HPCD to AM solution retarded the degradation rate of AM in the acidic region. However, ${\beta}-CD$ and HPCD rather acted as an accelerator of degradation in the neutral and alkaline regions. DMCD had a stabilizing effect at all pHs studied.

• Smart Structures and Systems
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• 제29권6호
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• pp.767-775
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• 2022

Metal additive manufacturing (AM), also known as metal three-dimensional (3D) printing, produces 3D metal products by repeatedly adding and solidifying metal materials layer by layer. During the metal AM process, products experience repeated local melting and cooling using a laser or electron beam, resulting in product defects, such as warpage, cracks, and internal pores. Such defects adversely affect the final product. This paper proposes the in situ monitoring-based warpage prediction of metal AM products with experimental feature extraction. The temperature profile of the metal AM substrate during the process was experimentally collected. Time-domain features were extracted from the temperature profile, and their relationships to the warpage mechanism were investigated. The standard deviation showed a significant linear correlation with warpage. The findings from this study are expected to contribute to optimizing process parameters for metal AM warpage reduction.

• 대한화학회지
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• 제40권8호
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• pp.579-584
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• 1996

폴리엔의 HOMO-LUMO gap, 정적 및 동적인 3차 편극율을 시간의존 Hartree Fock 반경험적 PM3, AM1, MODO, MINDO/3 방법을 이용하여 구하였다. $C_2H_4$로부터 $C_{32}H_{34}$까지 모든 계산이 수행되었다. HOMO-LUMO gap은 MINDO/3>MNDO>PM3>AM1 순서로 증가하였으며, THG, DC-EFIDHG, IDRI, OKE효과는 AM1>MNDO>PM3 순서로 증가하였다. 다양한 3차 효과는 THG>DC-EFISHG>IDRI>OKE순서로 증가함을 보여주고 있다.

• 한국자기학회지
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• 제18권2호
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• pp.54-57
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• 2008

Magnetic torquer하는 인공위성의 초기 자세제어에 사용 되는 부품으로 지구자기장하에서 자기 쌍극자 모멘트가 받는 비틀림력을 이용하여 인공위성의 회전을 방지하고 특정 방향으로 인공위성의 자세가 안정되게 한다. 본 연구에서 개발 한 magnetic torque는 소형위성에 사용되는 것으로, magnetic torque거 자기적 특성뿐만 아니라 위성 발사 시 및 인공위성 궤도에서의 환경에서도 그 특성이 보장될 수 있게 환경시험을 하였다. 개발한 magnetic torquer는 포화 자기 쌍극자 모멘트가 $15Am^2$, 선형도 특성을 보이는 구간이 ${\pm}12Am^2$이고 선형도가 0.3% 미만이면서 질량이 0.46 kg이고 소비전력이 자기 쌍극자 모멘트가 $10Am^2$에 1 Watt 이였다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(3)
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• pp.423-428
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• 1996

The feasibility study on burning Am-241, 243 and Cm-244 nuclides in a conventional PWR (Pressurized Water Reactor) was carried out by using the TRIFON code that was developed by the Institute of Theoretical and Experimental Physics in Russia in 1992. TRIFON code uses updated ABBN Russian nuclear cross section library. The reference reactor is the Korea nuclear power plant unit 8 (YGN 2). The burning effect of Am-241, 243 and Cm-244 nuclides was studied with UO$_2$(3.5 w/o)fuel assembly and MOX (4.44 w/o) fuel assembly. The loaded mass ratio of Am-241, 243 and Cm-244 nuclides was obtained from the mass ratio of Am-241, 243 and Cm-244 nuclides in 10 year cooling spent fuel with average discharge burnup of 33 GWD/MTU. The effective transmutation rates of Am-241, 243 and Cm-244 nuclides in UO$_2$ fuel assembly were found to be higher than those in MOX fuel assembly. The result from TRIFON code was compared to that from CASMO-3/NEM-3D code system. For more reliable calculation of transmutation for MA(Minor Actinides) more sophisticated decay chain scheme of MA should be investigated and nuclear cross section library of MA should be considerably improved.

• 한국통신학회논문지
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• 제22권10호
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• pp.2165-2170
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• 1997

본 논문에서는 CDMA 송신기에서 I/Q 불균형, Quadrature offset, 누설반송파와 같은 선형 왜곡 효과와 전력증폭기에서의 AM-AM, AM-PM 잡음과 같은 비선형 왜곡 효과가 시스템에 미치는 성능에 대하여 분석하였다. 이러한 왜곡효과들이 CDMA 송신기의 성능에 어떠한 영향을 미치는지 알아보기 위하여, 송신부의 특성을 나타내는 중요한 인자인 CDMA 변조지수(Modulation quality)를 왜곡 효과의 함수로 나타내었다. 본 논문의 결과로부터 IS-95 표준에서 요구되는 송신부의 성능을 만족하기 위한 각 왜곡효과들의 한계값을 선정할 수 있으며 이로부터 최적의 성능을 갖는 설계가 가능하다.

• 한국응용과학기술학회지
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• 제30권2호
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• pp.264-271
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• 2013

본 연구에서는 monoammonium phosphate가 WPU의 물성에 끼치는 영향을 필름 상태와 피혁(Full-Grain) 표면에 코팅을 하여 기계적 물성을 분석 하였다. DSC 결과 monoammonium phosphate가 많이 함유된 WPU-AM3 샘플이 $382^{\circ}C$로 높은 물성이 측정되었으며, 내용제성은 모든 샘플이 우수함을 알 수 있었다. 인장강도의 경우 monoammonium phosphate가 가장 많이 함유된 WPU-AM3($2.130kg_f/mm^2$)가 가장 낮은 물성을 보였으며, 연실율과 내마모성 역시 monoammonium phosphate가 많이 함유된 WPU-AM3가 615 % 및 52.07 mg.loss로 낮은 물성을 나타내었다.

• 한국약용작물학회지
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• 제21권4호
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• pp.262-267
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• 2013

The purpose of this study was to research for anti-oxidation and anti-wrinkle effects of Acar mono Sap (AM). To cosmetic effect of AM, safety effect (MTT assay), anti-wrinkle effect (elastase, MMP-1 inhibition assay) and anti-oxidant effect (DPPH assay) were measured. When water extract of AM was used for cell viability, it was over 100% at 6% (6 ml/100 ml in phosphate buffer) concentration. AM showed 45.7% elastase inhibition and 23.7% MMP-1 inhibition at 50% (50 ml/100 ml in phosphate buffer) concentration so that it had good anti-wrinkle characteristic. And AM showed 68.9% antioxidation capacity at 50% concentration by using a DPPH assay. Consequently, AM can be used as natural materials or additives for human skin owing to their beneficial biologic functions, including the anti-wrinkle effect, for cosmetic compositions.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2014년도 추계학술대회 및 정기총회
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• pp.48-48
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• 2014

Arbuscular Mycorrhizal Fungi(AMF) is widespread symbiont forming mutualistic relationship with plant root in terrestrial forest in ecosystem. They provide improved absorption of nutrient and water, and enhance the resistance against plant pathogen or polluted soil, therefore AM fungi are important for survival and maintaining of individual or community of plant. For last decade, many studies about the functional variation of AM fungi on host plant growth response were showed that different geographic isolates, even same species, have different effect on host plant. However, little was known about functional variation of AM fungal isolates originated single population, which provide important insight about intraspecific diversity of AMF and their role in forest ecosystem. In this study, four AM fungal isolates of Rhizophagus clarus were cultured in vitro using transformed carrot (Daucus carota) root and they showed the difference between isolates in ontogenic characteristics such as spore density and hyphal length. The plant growth response by mycorrhizas were measured also. After 20 weeks from inoculation of these isolates to host plants, dry weight, Root:Shoot ratio, colonization rates and N, P concentration of host plant showed host plant was affected differently by AM fungal isolates. This results suggest that AM fungi have high diversity in their functionality in intraspecific level, even in same population.