• 한국통신학회논문지
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• 제19권1호
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• pp.1-9
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• 1994

In general, when IIR digital filter are designed from analog filters, the bilinera transformation and the impluse invariant tramsformation are commonly used. It is known, however, that high frequency response of digital filters designed by these transformations can not be well approximated to the sampled analog signals. In this paper, the symbol pulse invariant transformation is analyzed theoretically so that the symbol pulse invariant transformation which was originally application to a rectangular pulse is newly applied to double rate pulse signals and generic shape pulse signals. Also, the relation of spectra between a transfer function of digital filter and one of analog filter is considered. Further, we apply to design the digital high pass filters using the symbol pulse invariant transformation method.

• Communications for Statistical Applications and Methods
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• 제22권4호
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• pp.333-348
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• 2015

In this paper, we study a generalization of the modified Weibull distribution. The generalization follows the recent work of Cordeiro et al. (2013) and is based on a class of exponentiated generalized distributions that can be interpreted as a double construction of Lehmann. We introduce a class of exponentiated generalized modified Weibull (EGMW) distribution and provide a list of some well-known distributions embedded within the proposed distribution. We derive some mathematical properties of this class that include ordinary moments, generating function and order statistics. We propose a maximum likelihood method to estimate model parameters and provide simulation results to assess the model performance. Real data is used to illustrate the usefulness of the proposed distribution for modeling reliability data.

• Journal of Microbiology
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• 제35권3호
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• pp.228-233
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• 1997

The MTF1 gene of Saccharomyces cerevisiae encodes a 43 kDa MITOCHONDRIAL RNA polymerase specificity factor which recognizes mitochondrial promoters to initiate correct transcription. To better understand structure-function of the MTF1 gene as well as the transcription mechanism of mitochondrial RNA polymerase, two cold-sensitive alleles of the MTF1 mutation were isolated by plasmid shuffling method after PCR-based random mutagenesis of the MTF1 gene. The mutation sites were analyzed by nucleotide sequencing. These cs phenotype mtf1 mutants were respiration competent on the nonfermentible glycerol medium at the permissive temperature, but incompetent at 13.deg.C. The cs phenotype allele of the MTF1, yJH147, encoded an L146P replacement. The other cs allele, yJH148, contained K179E and K214M double replacements. Mutations in both alleles were in a region of Mtflp which is located between domains with amino acid sequence similarities to conserved regions 2 and 3 of bacterial s factors.

• 소음진동
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• 제10권1호
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• pp.153-159
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• 2000

This paper presents a new method for including the dynamic stiffness of the stationary parts in rotordynamic analysis. As a consequence of the support dynamics, critical speeds are varied and/or additional critical speeds are introduced. Therefore, dynamic effects of the support are often significant in high speed turbomachinery, but most of analysis has considered the support as a rigid body or a simple structure. The proposed method is based on the coupled characteristics of the driving point and transfer frequency response functions of the support system to model the equivalent spring-mass series in finite element analysis. To demonstrate the applicability of the simulation procedures provided, it is applied to the rotor model of the double suction centrifugal pump. Results of the suggested equivalent-support rotor model including coupled effects agree well with the entire pump model.

• Computers and Concrete
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• 제30권3호
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• pp.209-224
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• 2022

In this paper, the artificial neural network (ANN) is employed to predict the flexural behavior of reinforced concrete (RC) beams retrofitted with carbon fiber/epoxy composites modified by carbon nanotubes (CNTs). Multiple techniques are used to improve the accuracy of the ANN prediction, as the data represents a multivalued function. These techniques include static ANN modeling, ANN modeling with load history, and ANN modeling with double load history. The developed ANN models are used to predict the load-displacement profiles of beams retrofitted with either CFRP or CNTs modified CFRP, flexural capacity, and maximum displacement of the beams. The results demonstrate that the ANN is able to predict the flexural behavior of the retrofitted RC beams as well as the effect of each parameter including the type of the used epoxy and the presence of the CNTs.

• 대한기계학회논문집A
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• 제20권3호
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• pp.806-815
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• 1996

The interlaminar fracture behavior of woven laminates under static and cyclic loadings has been studied using DCB(double cantilever beam) specimens. The effects of surface treatment and stiching on the fracture behavior of composite laminates are investigated experimentally. Fracture toughness has been improved by surface treatment because the surface treatment can change the fracture mechanism of laminates. SCB(stitched cantilever beam) model has been proposed to quantify the effect of through-thickness resinforcement(stiching) in improving the delamination crack growth resistance. Distributed loads which are transfered to through-thickness fibers can be calculated by the SCB model. And fracture energy increase due to the distributed load can be predicted by a power function of the distributed load. A new parameter agreed well proposed predict fatigue crack growth rate. The predictions using this parameter agreed well with the experimental data.

• 대한관절경학회지
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• 제6권1호
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• pp.7-13
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• 2002

목적 : 후방십자인대 손상과 치료에 대한 기전과 처치 및 재건에 대한 여러 가지 술식이 보고되고 있다. 이에 본 저자들은 후방십자인대 손상 환자에서 이중 고리 아킬레스 동종이식건을 이용한 후방십자인대 재건술을 보고하고자 한다. 대상 및 방법 : 1999년 5월부터 2000년 7월까지 본원 정형외과학 교실에서 수술한 후방십자인대 손상 8명을 대상으로 하였다. 이들은 모두 아킬레스 동종이식건으로 만든 두 개의 건 다발을 이용하여 대퇴골측은 대퇴골 이중 터널(dual femoral tunnel) 방법으로 고정하였고, 경골측은 한 개의 터널로 고정하는 관절경적 후방십자인대 재건술을 시행하였다. 수술 후 1년 이상 추시 관찰하였으며, 결과는 Lysholm Knee Score와 KT-2000관절 계측기를 이용한 도수 최대 전위 검사법으로 건측과 비교하여 안정성 여부 및 기능을 평가하였다. 결과 : 후방십자인대 재건술을 시행 받은 8명을 1년 이상 추시한 결과 이식건 파열이 관찰되었던 한 례를 제외하고는 불안정성을 보이지 않았다. 술 후 감염 등의 중대한 합병증을 보이는 환자는 없었으며 다만 한 예에서 술 중 이식골의 골절이 있었고 다른 한 예에서 술 후 부적절한 보호로 인한 이식건의 파열을 관찰할 수 있었다. 결론 : 후방십자인대 손상에 대한 아킬레스 동종이식건으로 만든 두 개의 건 다발을 이용한 대퇴골 이중 터널 고정술은 이전의 방법들에 비해 생역학적으로 안정적인 방법으로 간주되나 보다 장기적인 추시 관찰 결과가 필요할 것으로 사료된다.

• Clinical and Experimental Reproductive Medicine
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• 제11권2호
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• pp.17-25
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• 1984

Hypothalamic-pituitary function in patients of 6 selected groups of amenorrhea was evaluated by performing premarin test. Selected amenorrheic patients were divided into 6 groups of Turner's syndrome(5), adrenogenital syndrome(3), Sheehan's syndrome(4), moderate hyperprolactinemia(3), severe hyperprolactinemia(9) and functional oligoamenorrhea(9) the diagnoses of which were performed according to modified our own protocol for management of amenorrheic patients. As control 20 normally cycling women in mid follicular phase determined by their symptothermal charts during last 6 months designed by WHO were compared. The premarin test which is one of the tests evaluating the hypothalamic-pituitary function by the principle of negative and positive feed back effect's of estrogen was performed by injecting 20 mg of premarin in volus intravenously. The levels of serum LH before, 24, 48, 72, 96 and 120 hours after injection of premarin were measured by double antibody technique radioimmunoassay the reagents of which were supplied by WHO. The results were as follows: 1. Both negative and positive feed back effects by exogenous estrogen were well preserved even in the patients of gonadal dysgenesis although the baseline levels were much higher than normal. 2. In the patients of Sheehan's syndrome one could observe the minimal response of feed back effect in the case with minimal pituitary function. 3, Androgens in adrenogenital syndrome and prolactin in hyperprolactinemia may suppress mainly the positive feed back effect rather than the negative one. The suppressive effect can be abolished by proper treatments which can eliminate those suppressive hormones. 4. This premarin test may be beneficial for predicting the result of clomiphene in ovulation induction.

• 대한전자공학회논문지TC
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• 제42권10호
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• pp.39-50
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• 2005

본 논문에서는 IEEE 802.11 WLAN의 MAC인 DCF의 성능을 개선하는 알고리즘을 제안하고 이를 수학적으로 분석한다. IEEE 802.11 WLAN의 MAC에서는 데이터를 전송하기 위한 방법으로 "Distributed Coordination Function(DCF)"과 "Point Coordination Function(PCF)"를 사용하며, DCF의 경우 Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)를 기반으로 한다. CSMA/CA는 단말 간의 충돌을 줄이기 위해서 임의의 backoff time을 각 단말의 contention window(CW) 범위에서 결정한다. 단말은 패킷 전송 후 충돌시 윈도우 크기를 두배로 증가시키며, 성공적인 전송 후에는 윈도우 크기를 최소 CW로 감소하게 된다. 본 논문에서는 패킷의 정상적인 전송 후에 윈도우 값을 서서히 감소함으로써 현재 WLAN의 망 상태정보를 계속 활용함으로써 패킷 충돌 확률을 낮추는 알고리즘을 제안하였고, 불포화상태에서의 전송량에 대한 수학적 분석을 하였다 또한, 시뮬레이션을 통해 WLAN의 포화상태에서 전송량이 향상되었음을 보였고, 수학적 분석 결과와 시뮬레이션 결과가 일치함을 확인하였다.

• 한국컴퓨터정보학회논문지
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• 제15권12호
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• pp.175-180
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• 2010

본 논문에서는 고전적인 분자 동역학 시뮬레이션을 통해서 다양한 길이를 가진 이중벽 탄소나노 튜브로 만들어진 초고주파 나노 기계 공진기의 주파수 변동 특성을 분석한다. 분석의 목적은 이중벽 탄소나노 튜브 벽의 길이에 따라 변동하는 공진기의 주파수 분석이다. 실험 결과, 주파수 변동이 여러 가지 외벽 길이 값 L10에 대해서는 내벽/외벽 길이 비율 L5/L10의 함수로 최대 주파수로 정규화된 공진 주파수가 Pearson VII 함수에 잘 맞고, 여러 가지 내벽 길이 값에 대해서는 외벽/내벽 길이 비율의 함수로 최대 주파수로 정규화된 공진 주파수가 Gauss 분산 함수에 잘 맞는 것을 보여준다.