• 한국가구학회지
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• 제20권6호
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• pp.605-611
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• 2009

This paper reports the application of radiocarbon wiggle matching for Korean wooden artifacts such as furniture and Buddhist statues for precise dating. Ten biannual samples of 20 years (AD 1249-1268) for AMS (accelerator mass spectrometry) radiocarbon measurements were prepared from a board of the pedestal for Buddhist statue at Jeongsusa (temple) in Kangwhado, Korea, which was dendrochronologically dated. The average 95.4% confidence interval of radiocarbon dating without wiggle matching was 123 year. When wiggle matching technique was applied, it became 37 year, 3.3 times smaller than that without wiggle matching. The results indicated that wiggle matching technique using the calibration curve for northern hemisphere (IntCal04: International radiocarbon calibration curve announced in 2004) can produce precise dates for Korean wooden artifacts which possess as much as 20 tree rings.

• Steel and Composite Structures
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• 제35권6호
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• pp.765-777
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• 2020

In the context of classic conical shell formulation, nonlinear forced vibration analysis of truncated conical shells and annular plates made of multi-scale epoxy/CNT/fiberglass composites has been presented. The composite material is reinforced by carbon nanotube (CNT) and also fiberglass for which the material properties are defined according to a 3D Mori-Tanaka micromechanical scheme. By utilizing the Jacobi elliptic functions, the frequency-deflection curves of truncated conical shells and annular plates related to their forced vibrations have been derived. The main focus is to study the influences of CNT amount, fiberglass volume, open angle, fiber angle, truncated distance and force magnitude on forced vibrational behaviors of multi-scale truncated conical shells and annular plates.

• Journal of Welding and Joining
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• 제19권5호
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• pp.534-539
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• 2001

The formation mechanism of microconstituents in brazed joints of duplex stainless steel and Cr-Cu alloy which is an essential process of rocket engine manufacturing was investigated using Cu base insert metal. $SUS329J_3L$ and C18200 were used for base metal and AMS 4764 was used for insert metal. The brazing was carried out under various conditions. There were various phases in the joints, because of reaction between liquid insert metal and base metals. Since liquid insert metal reacts with duplex stainless steel, liquid Cu from insert metal infiltrated into the $\alpha/\beta$ interface of duplex stainless steel. Through the process of Cu infiltration, isolated stainless steel pieces come into the liquid insert metal. Since liquid insert metal reacts with Cr-Cu alloy. Cr precipitates from C18200 come into the liquid insert metal. With increment of bonding temperature and holding time, amounts and sizes of phases increased. but Cr-Mn compounds decreased at 1303k for 1.2ks and Mn-rich phases disappeared Fe-Cr compounds formed.

• 한국진공학회지
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• 제5권2호
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• pp.169-174
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• 1996

The applications of the high density plasma sources to the etching in semiconductor fabrication process are actively studied because of the more strict requirement from the dry etching process due to shrinking down of the critical dimension. But in the oxide etching with the high density plasma sources, abundant fluorine atoms released from the flurocarbon feed gas make it difficult to get the highly selective $SiO_2/Si$ etching. In this study, to improve the $SiO_2/Si$ etch selectivity through the control of the radical loss channels, we propose the wall heating , one of methods of controlling loss mechanisms. With appearance mass spectroscopy(AMS) and actinometric optical emission spectroscopy(OES), the increase of both radicals impinging on the substrate and existing in bulk plasma, and the decrease of the fluorine atom with wall temperature are observed. As a result, a 40% improvement of the selectivity was achieved for the carbon rich feed gas.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2008년도 학술발표회 논문집
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• pp.1053-1057
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• 2008

본 연구에서는 산악형 강수 해석을 위해 제주도내 강우관측 자료를 이용하여 확률강우량 산정 및 고도와의 선형회귀분석을 수행하였다. 제주도내 강우관측 자료는 기상관서 4개소 및 AWS(Automatic Weather System, 자동기상관측소) 13개소의 자료를 활용하였다. 확률강우량 산정시 AWS 강우관측 자료는 AMS(Annual Maximum Series, 연 최대치 계열) 모형을 적용하기에는 자료기간이 충분하지 않으므로 짧은 자료기간에 적합한 PDS(Partial Duration Series, 부분 기간치 계열) 모형을 적용하였다. 따라서 본 연구에서는 PDS의 대표적인 분포형인 GPD(Generalized Pareto Distribution)를 적용하여 지속시간별 확률강우량을 산정하였다. 산정된 지속시간별 확률강우량과 고도와의 관계를 확인하기 위하여 선형회귀분석을 수행하였다. 회귀분석 결과 확률강우량은 고도가 증가함에 따라 선형적으로 증가하였다. 또한, 재현기간이 길어질수록 고도에 따른 확률강우량 증가율도 증가하였다. 다만, 재현기간과 관계없이 지속시간이 짧을 경우 확률강우량과 고도와의 선형 관계는 약해지는 것으로 나타났다.

• ETRI Journal
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• 제29권6호
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• pp.785-793
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• 2007

In this paper, we present an integrated rail-to-rail fully differential operational transconductance amplifier (OTA) working at low-supply voltages (1.5 V) with reduced power consumption and showing high DC gain. An embedded adaptive biasing circuit makes it possible to obtain low stand-by power dissipation (lower than 0.17 mW in the rail-to-rail version), while the high DC gain (over 78 dB) is ensured by positive feedback. The circuit, fabricated in a standard CMOS integrated technology (AMS 0.35 ${\mu}m$), presents a 37 V/${\mu}s$ slew-rate for a capacitive load of 15 pF. Experimental results and high values of two quality factors, or figures of merit, show the validity of the proposed OTA, when compared with other OTA configurations.

• 전자공학회논문지SC
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• 제47권6호
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• pp.51-57
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• 2010

본 논문에서는 다중 안테나 시스템에서의 전송률과 안정성 측면에서의 최적의 성능을 발휘하기 위해 채널 추정오차에 강인한 적응형 다중입출력(MIMO) 스위칭 알고리즘을 제안한다. 제안된 논문은 무선 채널의 추정 오차에 대한 강인성을 확보하기 위하여 가변형 패킷오류 예측 방식에 기반을 두었으며, 기존의 MIMO 스위칭 방식에 비해 스펙트럼 효율이 약 8% 이상 증대 됨을 확인할 수 있었다.

• Journal of applied mathematics & informatics
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• 제4권1호
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• pp.63-82
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• 1997

In experimental situations where n two or three level fac-tors are involoved and n observations are taken then the D-optimal first order saturated design is an $n{\times}n$ matrix with elements $\pm$1 or 0, $\pm$1, with the maximum determinant. Cononical forms are useful for the specification of the non-isomorphic D-optimal designs. In this paper we study canonical forms such as the Smith normal form the first sec-ond and the jordan canonical form of D-optimal designs. Numerical algorithms for the computation of these forms are described and some numerical examples are also given.

• Journal of applied mathematics & informatics
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• 제7권1호
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• pp.237-245
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• 2000

In this paper, we consider to the adjustment weighting procedure in the two phase sampling scheme. In general, the unit nonresponses may be occured in the final survey operation. When the unit nonresponse be generated in survey, it is able to use the auxiliary variable for estimating of interest variable. In this viewpoint, we use the two kinds level of auxiliary variable, $X_{1k}$ and $X_{2k}$ for the calibration procedure. We proprose the two-step Newton's method in the calibration estimation procedure for the two phase sampling.

• Journal of applied mathematics & informatics
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• 제7권1호
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• pp.115-124
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• 2000

For a finite group G, #Cent(G) denotes the number of cen-tralizers of its clements. A group G is called n-centralizer if #Cent( G) = n. and primitive n-centralizer if #Cent(G) = #Cent(${\frac}{G}{Z(G)$) = n. In this paper we compute the number of distinct centralizers of some finite groups and investigate the structure of finite groups with Qxactly SLX distinct centralizers. We prove that if G is a 6-centralizer group then ${\frac}{G}{Z(G)$${\cong}D_8$,$A_4$, $Z_2{\times}Z_2{\times}Z_2$ or $Z_2{\times}Z_2{\times}Z_2{\times}Z_2$.