• Journal of applied mathematics & informatics
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• v.18 no.1_2
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• pp.197-204
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• 2005

For two distinct rank-1 matrices A and B, a rank-1 matrix C is called a separating matrix of A and B if the rank of A + C is 2 but the rank of B + C is 1 or vice versa. In this case, rank-1 matrices A and B are said to be separable. We show that every pair of distinct Boolean rank-l matrices are separable.

• Education of Primary School Mathematics
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• v.5 no.2
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• pp.111-119
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• 2001

Over the years, the benefits of instructional manipulatives in mathematics education have been verified by classroom practice and educational research. The purpose of this paper is to introduce how the instructional material, specifically, geoboard could be used and integrated in elementary mathematics classroom in order to develop student's mathematical concepts and process in terms of the following areas: (1) Number '||'&'||' Operation : counting, fraction '||'&'||' additio $n_traction/multiplication (2) Geometry : geometric concepts (3) Geometry : symmetry '||'&'||' motion (4) Measurement : area '||'&'||' perimeter (5) Probability '||'&'||' Statistics : table '||'&'||' graph (6) Pattern : finding patterns Further, future study will continue to foster how manipulatives will enhance children's mathematics knowledge and influence on their mathematics performance.

• Proceedings of the SAREK Conference
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• 2004.06a
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• pp.104-104
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• 2004

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.658-660
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• 1998

계층적 자료구조인 사진트리는 이진 영상을 표현하는데 매우 중요한 자료구조이다. 선형 사진트리는 사진트리를 메모리에 저장하는데 매우 효율적이므로 사진트리와 관련된 연산의 수행을 위해 많은 연구가 진행되어 왔다. 본 논문에서는 RMESH(Reconfigurable MESH) 구조에서 3-차원 n$\times$n$\times$n 프로세서를 사용하여 선형 사진트리로 표현된 이진 영상의 둘레 길이를 계산하는 상수 시간 알고리즘을 제안한다.

• Kyungpook Mathematical Journal
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• v.46 no.1
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• pp.89-96
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• 2006

For a rank-1 matrix A, there is a factorization as $A=ab^t$, the product of two vectors a and b. We characterize the linear operators that preserve rank and some equivalent condition of rank-1 matrices over a chain semiring. We also obtain a linear operator T preserves the rank of rank-1 matrices if and only if it is a form (P, Q, B)-operator with appropriate permutation matrices P and Q, and a matrix B with all nonzero entries.

• Steel and Composite Structures
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• v.36 no.4
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• pp.383-398
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• 2020

This paper investigates the progressive collapse behavior of 3D steel-framed gravity buildings under fires with a cooling phase. The effect of fire protections and bracing systems on whether, how, and when a gravity building collapses is studied. It is found that whether a building collapses or not depends on the duration of the heating phase, and it may withstand a "short-hot" fire, but collapses under a mild fire or a "long-cool" fire. The collapse time can be conservatively determined by the time when the temperature of steel columns reaches a critical temperature of 550 ℃. It is also found that the application of a higher level of fire protection may prevent the collapse of a building, but may also lead to its collapse in the cooling phase due to the delayed temperature increment in the heated members. The tensile membrane action in a heated slab can be resisted by a tensile ring around its perimeter or by tensile yielding lines extended to the edge of the frame. It is recommended for practical design that hat bracing systems should be arranged on the whole top floor, and a combination of perimeter and internal vertical bracing systems be used to mitigate the fire-induced collapse of gravity buildings. It is also suggested that beam-to-column connections should be designed to resist high tensile forces (up to yielding force) during the cooling phase of a fire.

• The Korean Journal of Cytopathology
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• v.9 no.1
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• pp.63-68
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• 1998

Fine needle aspiration cytology of "cold" nodules of the thyroid has proved to be of great value in their preoperative diagnosis. Most types of thyroid tumors are readily recognizable from characteristic cellular patterns in the smears of needle aspirates. But follicular neoplasms present some problems because the cytomorphology of the adenomas frequently is same as in carcinoma. For differentiation of benign from malignant follicular neoplasms of the thyroid we tested the usefulness of two objective parameters - nuclear area and perimeter - by morphometry. This study was made on fine needle aspirates from 30 cases with cytologic diagnosis of follicular neoplasm of thyroid. The histologic classification was follicular adenoma in 22 cases and follicular carcinoma in 8 cases. As a reference group we used seven caes with nodular hyperplasia. The smears of aspirates were stained by Papanicolaou method. On each slide 200 randomly selected cells with intact nuclei were measured. The mean value of nuclear area are $25.32{\pm}5.50{\mu}m^2,\;34.08{\pm}7.50{\mu}m^2\;and\;39.97{\pm}6.63{\mu}m^2$ in nodular hyperplasia, follicular adenoma, and follicular carcinoma, respectively. The mean value of perimeter are $19.48{\pm}2.26{\mu}m,\;22.95{\pm}2.65{\mu}m\;and\;24.78{\pm}2.23{\mu}m$ in nodular hyperplasia, follicular adenoma and follicular carcinoma, respectively. The mean nuclear areas and perimeters of cells from follicular adenoma were significantly larger than those from nodular hyperplasia (p<0.05). The mean nuclear areas and perimeters of cells from follicular carcinoma were larger than those from follicular adenoma but the differences are not significant statistically(p>0.05). Therefore, morphometric assessment alone is inadequate to predict malignancy in thyroid aspirates.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.1
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• pp.13-23
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• 2015

The paper experimentally deals with the radial in-plane vibration characteristics of disk-shaped piezoelectric transducers. The radial in-plane motion, which is induced due to Poisson's ratio in the piezoelectric disk polarized in the thickness direction, was measured by using an in-plane laser vibrometer, and the natural frequencies were measured by using an impedance analyzer. The experimental results have been compared with theoretical predictions obtained by simplified theoretical and finite-element analyses. It appears that the fundamental mode of a piezoelectric disk transducer is a radial mode and its radial displacement distribution from the center to the perimeter is not monotonic but shows maximum slightly apart from the perimeter. The theoretically-calculated fundamental frequencies agree well with the finite-element results for small thickness-to-diameter ratio, and they are accurate within 7 % error for the ratio up to 0.4.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.464-470
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• 2011

V2V (Vehicle-to-Vehicle) is a special kind of VANET (Vehicular Ad-hoc Network), which has high mobility and frequent topology changes and causes the link breakage problem. To resolve this problem, geographic routing protocols such as greedy forwarding are proposed. However, the greedy forwarding approach selects the node closest to the destination node as the transfer node within the transmission range so that it may cause many problems owing to many intersections and many changes in vehicular traffic in urban areas. The paper proposes a greedy perimeter urban routing (GPUR) algorithm considering the presence of 2-hop neighbor nodes and the road characteristics. Simulation results using ns-2 reveal that the proposed GPUR algorithm significantly reduces the routing error problem and the probability of local maximum than the existing routing protocols.

• The KIPS Transactions:PartC
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• v.16C no.4
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• pp.535-542
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• 2009

Wireless Sensor Network (WSN) is a wireless network consisting of spatially distributed autonomous devices, using sensors to cooperatively monitor physical or environmental conditions. WSNs face the critical challenge of sustaining long-term operation on limited battery energy. Coverage maintenance has been proposed as a promising approach to prolong network lifetime. Mobile sensors equipped with communication devices can be leveraged to overcome the coverage problem. In this paper, we propose a stepwise movement scheme using perimeter coverage property for the coverage maintenance problem. In our scheme, each sensor monitors neighboring dead nodes, determines vulnerable node (i.e. dead node which makes uncovered area), computes the center of uncovered area HC, and makes a coordinated stepwise movement to compensate the uncovered area. In our experimental results, our scheme shows at least 50 % decrease in the total moving distance which determines the energy efficiency of mobile sensor.