• 한국화재소방학회논문지
• /
• 제18권4호
• /
• pp.86-92
• /
• 2004

일정한 외부 복사열원(10, 15, 20, 25, and 35 ㎾/㎡)에 노출된 목재의 탄화속도를 측정하기 위해 목재의 종류별로 5개의 시료를 사용하였으며, 목재에 복사열원을 노출시키기 위해 Cone heater를 사용하였다. 시료의 크기는 100㎜×100㎜×50㎜로 Redwood, White oak, Douglas fir, Maple의 4종류의 목재를 사용하였다. 연구결과, 일정한 외부 복사열원에 노출된 목재의 탄화는 시간의 선형함수로 간주 될 수 있다. 일정한 외부 복사열원에 따른 목재의 종류별 탄화속도를 계산할 결과 Redwood가 가장 빠르게 나타나고. Douglas fir가 가장 느리게 나타났으며. 복사열원이 35㎾/㎡일 때 탄화속도는 10㎾/㎡일 때 보다 약 2배정도 빠르게 진행됨을 알 수 있었다. 식 (2)의 α 값은 외부복사열이 10, 15, 20, 25, 35㎾/㎡일 때 각각 1.02, 1.16, 1.23, 1.32, 1.44임을 평가할 수 있었다.

• 한국안전학회지
• /
• 제22권6호
• /
• pp.46-54
• /
• 2007

The purpose of this study was to examines the burning rate of fire retardant treated wood in the cone heater with a one-dimensional integral model. The wood samples used in this study were four species. The species of woods are Redwood, White oak, Douglas fir and Maple. Each sample was nominally 50mm thick and 100mm square. Samples were exposed to a range of incident heat fluxes 10 to $35kW/m^2$ using the cone heater. A one-dimension integral model has been used to predict burning rate, heat of gasification, flame heat fluxes, charring rate and char depth of samples. As a result measurement of mass loss rate, softwoods(Redwood and Douglas fir) has relatively low value than those for hardwoods(White oak and Maple). Average charring rate of woods in case of fire retardant treatment showed reduction effect of 41.29%, 50.00%, 48.18% and 60.82% for Redwood, Douglas fir, White fir and Maple, respectively. Almost all the predictions from integral model showed faster charring than those measured. Average difference between predictions and experimental data was 16%, 9.5% and 11.8% for N, F1 and F2 respectively. Water-soluble fire retardant used in this study find out more effect in hardwood than softwood from the result of measurement of mass loss rate and average charring rate.

• 대한수학회보
• /
• 제42권3호
• /
• pp.543-554
• /
• 2005

In this paper it is proved that for p-hyponormal or log-hyponormal operator A there exist an associated hyponormal operator T, a quasi-affinity X and an injection operator Y such that TX = XA and AY = YT. The operator A and T have the same spectral picture. We apply these results to give brief proofs of some well known spectral properties of p-hyponormal and log­hyponormal operators, amongst them that the spectrum is a con­tinuous function on these classes of operators.

• 대한수학회보
• /
• 제42권3호
• /
• pp.571-577
• /
• 2005

In this paper we prove that if T is a k-th root of a p­hyponormal operator when T is compact or T$^{n}$ is normal for some integer n > k, then T is (generalized) scalar, and that if T is a k-th root of a semi-hyponormal operator and have the property $\sigma$(T) is contained in an angle < 2$\pi$/k with vertex in the origin, then T is subscalar.

• 대한수학회보
• /
• 제43권4호
• /
• pp.671-677
• /
• 2006

Let $A, B{\in}B(H)$ be Hilbert space contractions, and let ${\Delta}_{AB}$ be the elementary operator ${\Delta}_{AB}:X{\rightarrow}AXB-X$. A number of conditions which are equivalent to '${\Delta}_{AB}$ has closed range' are proved.

• 한국전자파학회논문지
• /
• 제18권1호
• /
• pp.96-104
• /
• 2007

현재 국제적으로 수풀 손실 예측 모델이나 측정 데이터가 매우 부족하다. 본 논문에서는 2005년과 2006년, 2년에 걸쳐 $1{\sim}6\;GHz$ 대역 국내 수풀 및 가로 환경에 많이 분포하는 소나무(pine tree), 히말라야시다(hymalaya cedar),플라타너스나무(plane tree), 메타나무(dawn-redwood tree)등의 수풀에 대한 수풀 손실 특성 측정 수행 결과로부터, ITU-R P.833에서 제시하고 있는 RET(radiative energy transfer) 모델 파라미터를 도출하였으며, 모델 보정을 시도하였다. 본 연구 결과는 2005년, 2006년 ITU-R SG WP 3J 회의에서 권고서에 반영되었다.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제7권3호
• /
• pp.121-129
• /
• 2002

Existing methods for optimization of sequences by random mutagenesis generate libraries with a small number of mostly deleterious mutations, resulting in libraries containing a large fraction of non-functional clones that explore only a small part of sequence space. Large numbers of clones need to be screened to find the rare mutants with improvements. Library display formats are useful to screen very large libraries but impose screening limitations that limit the value of this approach for most commercial applications. By contrast, in both classical breeding and in DNA shuffling, natural diversity is permutated by homologous recombination, generating libraries of very high quality, from which improved clones can be identified with a small number of complex screens. Given that this small number of screens can be performed under the conditions of actual use of the product, commercially relevant improvements can be reliably obtained.

• Korean Journal of Mathematics
• /
• 제19권2호
• /
• pp.205-209
• /
• 2011

Let $\mathcal{QA}$ denote the class of bounded linear Hilbert space operators T which satisfy the operator inequality $T^*|T^2|T{\geq}T^*|T|^2T$. Let $f$ be an analytic function defined on an open neighbourhood $\mathcal{U}$ of ${\sigma}(T)$ such that $f$ is non-constant on the connected components of $\mathcal{U}$. We generalize a theorem of Sheth [10] to $f(T){\in}\mathcal{QA}$.

• 대한수학회지
• /
• 제43권4호
• /
• pp.899-909
• /
• 2006

Let T be a bounded linear operator on a complex infinite dimensional Hilbert space $\scr{H}$. We say that T is a quasi-class A operator if $T^*\|T^2\|T{\geq}T^*\|T\|^2T$. In this paper we prove that if T is a quasi-class A operator and f is a function analytic on a neigh-borhood or the spectrum or T, then f(T) satisfies Weyl's theorem and f($T^*$) satisfies a-Weyl's theorem.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제1권1호
• /
• pp.75-80
• /
• 2001

Rule inconsistency is an important issue that is needed to be addressed while designing efficient and optimal fuzzy rule bases. Automatic generation of fuzzy rules from data sets, using machine learning techniques, can generate a significant number of redundant and inconsistent rules. In this study we have shown that it is possible to provide a systematic approach to understand the fuzzy rule inconsistency problem by using the proposed measure called the Commonality measure. Apart from introducing this measure, this paper describes an algorithm to optimize a fuzzy rule base using it. The optimization procedure performs elimination of redundant and/or inconsistent fuzzy rules from a rule base.