• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2011년도 학술발표회
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• pp.185-185
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• 2011

Mapping of artificial levee lines, one of major tasks in river zone mapping, is critical to prevention of river flood, protection of environments and eco systems in river zones. Thus, mapping of artificial levee lines is essential for management and development of river zones. Coastal mapping including river zone mapping has been historically carried out using surveying technologies. Photogrammetry, one of the surveying technologies, is recently used technology for national river zone mapping in Korea. Airborne laser scanning has been used in most advanced countries for coastal mapping due to its ability to penetrate shallow water and its high vertical accuracy. Due to these advantages, use of LiDAR data in coastal mapping is efficient for monitoring and predicting significant topographic change in river zones. This paper introduces a method for construction of a 3D artificial levee line using a set of LiDAR points that uses normal vectors. Multiple steps are involved in this method. First, a 2.5-dimensional Delaunay triangle mesh is generated based on three nearest-neighbor points in the LiDAR data. Second, a median filtering is applied to minimize noise. Third, edge selection algorithms are applied to extract break edges from a Delaunay triangle mesh using two normal vectors. In this research, two methods for edge selection algorithms using hypothesis testing are used to extract break edges. Fourth, intersection edges which are extracted using both methods at the same range are selected as the intersection edge group. Fifth, among intersection edge group, some linear feature edges which are not suitable to compose a levee line are removed as much as possible considering vertical distance, slope and connectivity of an edge. Sixth, with all line segments which are suitable to constitute a levee line, one river levee line segment is connected to another river levee line segment with the end points of both river levee line segments located nearest horizontally and vertically to each other. After linkage of all the river levee line segments, the initial river levee line is generated. Since the initial river levee line consists of the LiDAR points, the pattern of the initial river levee line is being zigzag along the river levee. Thus, for the last step, a algorithm for smoothing the initial river levee line is applied to fit the initial river levee line into the reference line, and the final 3D river levee line is constructed. After the algorithm is completed, the proposed algorithm is applied to construct the 3D river levee line in Zng-San levee nearby Ham-Ahn Bo in Nak-Dong river. Statistical results show that the constructed river levee line generated using a proposed method has high accuracy in comparison to the ground truth. This paper shows that use of LiDAR data for construction of the 3D river levee line for river zone mapping is useful and efficient; and, as a result, it can be replaced with ground surveying method for construction of the 3D river levee line.

• Journal of Electrical Engineering and information Science
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• 제2권3호
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• pp.51-60
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• 1997

A practically applicable collision free trajectory planning technique for tow robot systems is proposed. The robot trajectories considered in this work are composed of many segments, an at the intersection points between segments robots stop to assemble, weld, ordo other jobs by the attached a end-effectors. The proposed method is based on the Planning-Coordination Decomposition where planning is to find a trajectory of each robot independently according to their tasks and coordination is to find a velocity modification profile to avoid collision with each other. To fully utilize the independently planned trajectories and to ensure no geometrical path deviation after coordination, we develop a simple technique added the minimal delay time to avoid collision just before moving along path segments. We determine the least delay time by the graphical method in the Coordination space where collisions and coordinations are easily visualized. We classify all possible cases into 3 group and derive the optimal solution for each group.

• 치과방사선
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• 제11권1호
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• pp.23-32
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• 1981

The purpose of this study was to assess temporomandibular joint subluxation by means of cephalometry using two lateral cephalograms from each person with in centric occlusion and wide-open mouth position, and to compare patient group with subluxation to normal control group in the measurements and correlation coefficient. The 200 cephalograms of 100 Korean adults, patient group consisted of 24 females and 26 males ranged from 17 to 63 years age and the normal control group consisted of 20 females and 30 males ranged from 18 to 56 years age, were studied and analyzed statistically. The results were as follows; 1. In the comparison of patient group vs normal control group in the measurements, statistically significant differences were found in C-C', C'-PTM, K-FH, K-PTM, Gn-Gn', C-S-C', Gn-S-Gn', Gn-K-Gn', GoGn-SN, and GoGn-Go'Gn'. K-point* of patient group was located antero - superiorly than of normal control group, and the significance level was higher in K-PTM than in K-FH. There was no statistically significant difference found in local relationship of C-point between patient group and normal control group. The values of correlation coefficient among all measurements were in 0.958≥r≥-0.760, and the highest value was in Gn-Gn' to GoGn-Go'Gn' and Gn-K-Gn' to Gn-Gn', and the lowest value was in C'-PTM to Gn-K-Gn' of normal control group. K was determined as a point of intersection by a perpendicular bisector of Gn-Gn' and a perpendicular bisector of C-C'.

• 대한치과교정학회지
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• 제48권3호
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• pp.143-152
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• 2018

Objective: This study examined cone-beam computed tomography (CBCT)-derived multiplanar-reconstructed (MPR) cross-sections to clarify the salient characteristics of patients with skeletal class III malocclusion with midface deficiency (MD). Methods: The horizontal and sagittal plane intersection points were identified for middle-third facial analysis in 40 patients in the MD or normal (N) groups. MPR images acquired parallel to each horizontal plane were used for length and angular measurements. Results: A comparison of the MD and N groups revealed significant differences in the zygoma prominence among female patients. The convex zygomatic area in the N group was larger than that in the MD group, and the inferior part of the midface in the N group was smaller than that in the MD group for both male and female patients. A significant difference was observed in the concave middle maxillary area among male patients. Conclusions: This study was conducted to demonstrate the difference between MD and normal face through MPR images derived from CBCT. Male patients in the MD group had a more flattened face than did those in the N group. Female patients in the MD group showed a concave-shaped lower section of the zygoma, which tended to have more severe MD. These findings indicate that orthognathic surgery to improve skeletal discrepancy requires different approaches in male and female patients.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권9호
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• pp.2442-2454
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• 2012

To ensure the security of wireless sensor networks, it is important to have a robust key management scheme. In this paper, we propose a Quorum-based key management scheme. A specific sensor, called as key distribution server (KDS), generates a key matrix and establishes a quorum system from the key matrix. The quorum system is a set system of subsets that the intersection of any two subsets is non-empty. In our scheme, each sensor is assigned a subset of the quorum system as its pre-distributed keys. Whenever any two sensors need a shared key, they exchange their IDs, and then each sensor by itself finds a common key from its assigned subset. A shared key is then generated by the two sensors individually based on the common key. By our scheme, no key is needed to be refreshed as a sensor leaves the network. Upon a sensor joining the network, the KDS broadcasts a message containing the joining sensor ID. After receiving the broadcast message, each sensor updates the key which is in common with the new joining one. Only XOR and hash operations are required to be executed during key update process, and each sensor needs to update one key only. Furthermore, if multiple sensors would like to have a secure group communication, the KDS broadcasts a message containing the partial information of a group key, and then each sensor in the group by itself is able to restore the group key by using the secret sharing technique without cooperating with other sensors in the group.

• 대한족부족관절학회지
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• 제6권2호
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• pp.139-143
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• 2002

Purpose: We analyzed the Metatarso-Phalangeal Oblique Angle(MPOA) of Diabetic foot. Materials and methods: We studied retrospectively 60 cases of diabetic foot in 52 patients, for the evaluation of the correlations between clinical outcomes and radiologic findings in the conservative management group (Group A; 36 cases) and the major operation group (Group B; 24 cases). We measured MPOA on AP view. The MPOA was defined as the intersection angle of the Metatarso-Phalangeal Break Line (a line passing from the second to fifth metatarsal heads) and the long axis of foot in sagittal plane. We performed the statistical analysis between MPOA and clinical outcomes. by independent t-test. Results: The mean of MPOA in group B, $70.79^{\circ}$ (range: $62.8^{\circ}-81.3^{\circ}$), was significantly higher than that in group A, $68.04^{\circ}$ (range: $62.0^{\circ}-76.4^{\circ}$). The mean of MPOA in patients of fore foot lesions(30 cases), $71.30^{\circ}$ (range: $62.0^{\circ}-71.5^{\circ}$), was significantly higher than that in patients of hind foot lesions(30 cases), $66.97^{\circ}$(range: $62.8^{\circ}-81.3^{\circ}$). Conclusions: We recognized the MPOA might be useful simple parameter in assessing the diabetic foot.

• 한국과학교육학회지
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• 제19권3호
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• pp.441-447
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• 1999

본 연구는 초등학생들의 정신용량과 인지양식에 따라 과학탐구능력에 차이가 있는지 알아보는데 목적이 있다. 대구시내에 소재하고 있는 초등학교의 5학년 264명을 대상으로 조사하였다. 과학탐구능력을 측정하기 위한 과학탐구능력 검사(TSPS), 정신용량을 측정하기 위한 FIT(Figural Intersection Test), 인지양식을 측정하기 위한 잠입도형검사(GEFT) 등 3가지 지필 검사를 실시하여 자료를 수집하였다. 본 연구의 결과 학생들의 정신용량이 클수록 과학탐구능력의 성취도가 높았다. 장독립적인 학생이 장의존적인 학생보다 통계적으로 유의미 (p<.05)하게 과학탐구능력의 성취도가 높았다. 그러나 과학탐구능력에 미치는 정신용량과 인지양식의 상호작용 효과는 통계적으로 유의미하지 않는 것으로 나타났다. 이러한 본 연구의 결과는 정신용량과 인지양식이 과학탐구능력의 발달에 중요한 역할을 하고 있음을 시사한다. 아울러, 본 연구는 과학교육 연구에서 신피아제적 접근에 대한 가능성을 제공한다. 본 연구 결과로 볼 때, 과학 탐구과제의 수행에 인지 발달이 매우 중요한 변인임을 시사한다.

• Composites Research
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• 제31권4호
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• pp.156-160
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• 2018

본 논문에서는 콘형 복합재 격자구조체의 구조안전성 평가 기법에 대해 연구를 수행하였다. 콘형 복합재격자구조체의 구조안전성 평가는 유한요소해석을 통해 수행되었다. 구조안전성 평가를 위한 유한요소모델은 솔리드 요소를 사용하여 생성하였다. 섬유 교차부와 비교차부의 물성 차이를 고려하기 위해 섬유 체적률을 고려한 기계적 물성을 적용하였다. 구조해석 기법의 검증을 위해 콘형 복합재 격자구조체의 압축 시험을 수행하였다. 시험과 해석의 비교 결과, 약 2%의 변위 오차가 발생하여 잘 일치하는 것을 확인하였다.

• 대한교통학회지
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• 제10권1호
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• pp.41-54
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• 1992

The purpose of this thesis is to construct a model to estimate the delay that vehicles arriving randomly will be experienced at an isolated singalized intersection. To do this the following objectives are set in this study: (i) An what distance a random arrival pattern occurs after a platoon of vehicles are dis-charged from the stop line; (ii) A model which estimates the average delay per through-vehicle with respect to the de-gree of saturation; and (iii) The relation between the stepped delay and average approach delay per vehicle. The following are the findings of this study: (i) A random arrival pattern on the first second and third lanes occur 300,400 and 300m downstream from stop line rdspectively. A random arrival pattern on lane group occurs 500m downstream from the stop line ; (ii) A model for the estimation of approach delay has been developed in such a way that up to x=0.7 the delay increases linearly and beyond 0.7 the delay increases rapidly in a form of second order polynomial due to high degree of saturation : and (iii) Approach delay equals approximately 1.21 times of stopped delay.

• 한국세라믹학회지
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• 제23권4호
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• pp.35-40
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• 1986

The production process of a fine size fraction of Korean kaolin by ball milling is studied in this paper by analyzing the size distribution the size distribution of products with the Rosin-rammle formular and the rate process of cumulative size fractions with Alyavdin-Chujyo's formular. The size distribution is found to be divided in three regions a coarser part influenced by feed size an intermediate part where the size distribution shows a clear straight line relationship on Rosin-Rammler chart and the finest part with the ultimate limit of fineness by ball milling. Alyavdin-Chujyo's relationship is found to be valid over a very wide range of milling conditions. For different feed sizes the Alyavdin-Chujyo's relationship gives a group of straight lines with a common intersection point which can be defined as the limiting point of the persistent component region.