• Geomechanics and Engineering
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• 제13권4호
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• pp.621-640
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• 2017

The double-row long-short composite anti-sliding piles system is an effective way to control the landslides with high thrust. In this study, The double-row long-short composite anti-sliding piles with different load segment length (cantilever length) and different pile row spacing were studied by a series of physical tests, by which the influences of load segment length of rear-row piles as well as pile row spacing on the mechanical response of double-row long-short composite anti-sliding pile system were investigated. Based on the earth pressures in front of and behind the piles obtained during tests, then the maximum bending moments of the fore-row and the rear-row piles were calculated. By ensuring a equal maximum moments in the fore-row and the rear-row piles, the optimum lengths of the rear-row piles of double-row long-short composite system under different piles spacing were proposed. To investigate the validity of the reduced scale tests, the full-scale numerical models of the landside were finally conducted. By the comparisons between the numerical and the physical test results, it could be seen that the reduced scale tests conducted in this study are reliable. The results showed that the double-row long-short composite anti-sliding piles system is effective in the distribution of the landslide thrust to the rear-row and the fore-row piles.

• International Journal of Aeronautical and Space Sciences
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• 제16권4호
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• pp.500-509
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• 2015

The numerical simulation of two-dimensional moving blade row interactions is conducted by CFD means to investigate the interactions between the front and rear propeller in a stratospheric airship contra-rotating open propeller configuration caused by different rotational speeds. The rotational speed is a main factor to affect the propeller Reynolds number which impact the aerodynamic performance of blade rows significantly. This effect works until the Reynolds number reaches a high enough value beyond which the coefficients become independent. Additionally, the interference on the blade row has been revealed by the investigation. The front blade row moves in the induced-velocity field generated by the rear blade row and the aerodynamic coefficients are influenced when the rear blade row has fast RPMs. The rear blade row moving behind the front one is affected directly by the wake and eddies generated by the front blade row. The aerodynamic coefficients reduce when the front blade row has slow RPMs while increase when the front blade row moves faster than itself. But overall, the interference on the front blade row due to the rear blade row is slight and the interference on the rear blade row due to the front blade row is much more significant.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.353-362
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• 1993

The purpose of this study is to develop a crop-row detector which can be applied to an automatic row following control for cultivators or thinning machines. In this report, a possibility of new crop-row detecting method was discussed. This detecting method consists of two principal means. One is the hardware means to convert the two dimensional crop-row vision to the compacted one dimensional information. The conversion is achieved by a color line sensor and a rotating mirror. In order to extract crop-row , R and G signals of RGB color system are used. The locations of two different points on the target row are detected by this means. Another is the software means to estimate the offset value and the heading angle between the detector and the target row which can be assumed as a straight line. As a result of discussion, it was concluded that this detecting method would be accurate enough for practical use.

• 한국환경복원기술학회지
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• 제17권6호
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• pp.29-37
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• 2014

The objective of this study is to estimate the cost and benefits of street trees for their planting types, specifically, single row, single row+bottom, double row, double row+bottom. Different planting types are compared and analyzed by using Net Present Value (NPV) and benefit-cost ratio (BCR). Existing data are collected from the literature reviews for the use of meta-analysis method for estimating cost and benefit. The elements for analyzing costs are management and planting costs, and benefits are air purification, energy saving and landscape view. The discount rate is applied at a minimum of 3% and a maximum of 5.5%. The unit used in this calculation is km/year. The result shows that the net benefit is highest in double row, followed by single row, double row+bottom, and single row+bottom. The BCR is the highest in double row, followed by single row, double row+bottom, and single row+bottom. The BCR reaches the break-even point from 9 to 17 years depending on the planting types.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1034-1039
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• 2004

The row-by-row heat transfer characteristics of fin-and-tube heat exchangers having wavy fins were experimentally investigated. Three samples having different rows (one, two and three) were tested. Results show that the heat transfer coefficient is strongly dependent on the tube row. The heat transfer coefficient of the first row is larger than those of second or third rows. However, the difference decreases as the Reynolds number increases. The heat transfer coefficients of the second and the third row are approximately the same, probably due to increased mixing of bulk flow by wavy channels. Although samples have different tube row, the heat transfer coefficients of same row are approximately the same.

• 설비공학논문집
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• 제19권2호
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• pp.149-155
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• 2007

The row-by-row heat transfer characteristics of fin-and-tube heat exchangers were experimentally investigated. Three wavy fin samples having different rows (one, two and three) and one plain fin sample (three row) were tested for $600{\leq}Re_{D}{\leq}4,000$. The heat transfer data were obtained for individual rows, and the corresponding heat transfer coefficients were reduced from the data. Results showed that the heat transfer coefficients were strongly dependent on the tube row. The heat transfer coefficient decreased as the tube row increased. However, the row effect was different depending on the fin shape. For the wavy fin, the row effect significantly decreased as the Reynolds number increased, yielding approximately the same heat transfer coefficients at $Re_{D}{\approx}2,500$. For the plain fin, however, the row effect lasted for the whole Reynolds number range. The increased mixing of bulk flow by wavy channels appears to induce high heat transfer coefficient (accordingly diminishing row effect) at downstream rows. The heat transfer coefficients of individual rows were higher for heat exchangers having larger tube rows.

• 대한수학회지
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• 제36권2호
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• pp.333-344
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• 1999

In [4], it was shown that an n by n orthogonal matrix which has a row of nonzeros has at least ( log2n + 3)n - log2n +1 nonzero entries. In this paper, the matrices achieving these bounds are constructed. The analogous sparsity problem for m by n row-orthogonal matrices which have a row of nonzeros in conjectured.

• 설비공학논문집
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• 제27권5호
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• pp.254-262
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• 2015

Heat transfer rate can be increased by increasing the heat transfer area. In this study, wide louver fin-and-tube heat exchangers with $P_t/P_l=1.03$ were tested and compared with louver fin-and-tube heat exchanger with $P_t/P_l=0.6$. Results show that heat transfer capacities of wide louver samples are larger (9.8% at one row, 13.6% at two row and 4.1% at three row) than those of conventional louver samples. Considering the area ratio of 1.78, the increase of heat transfer capacity is rather small, possibly due to the smaller heat transfer coefficient and fin efficiency of the wide louver sample. The j factor of the louver fin was 67% larger at one row, 42% larger at two row and 52% larger at three row. The f factor of the louver fin was 81% larger at one row, 63% larger at two row and 60% larger at three row. The effect of fin pitch on j and f factors are not pronounced and the j factor decreased as the number of tube row increased.

• Clinics in Shoulder and Elbow
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• 제9권1호
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• pp.89-95
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• 2006

Purpose: Arthroscopic repair of rotator cuff tears are many techniques that have been developed to improve the initial postoperative strength of the repair. There was a doubt that current arthroscopic cuff repairs using a single row of suture anchors reproduce insufficient area of the anatomic cuff insertion, and concerns about failure of fixation often lead surgeons to limit early motion. Newer technique of double-row repair in arthroscopic treatment may provide initial stronger fixation and more contact with bone at the repair site than single-row repair did. We studied the comparison between clinical outcomes of arthroscopic single- and double-row repair in cuff tears at 1year postoperatively. Materials and methods: We retrospectively analyzed 40 shoulders with single-row repair and 38 shoulders with double-row repair of full-thickness rotator cuff tears between May 2002 and October 2004. Out of total 78 shoulders, 42 (54%) were male patients and 36 (46%) were female patients and the mean age at surgery was 56 years. All patients were diagnosed by physical examination and MRI. At 1year' follow-up after operation, we evaluated with the ASES and the Constant scoring system, and measured muscle power of abduction, internal and external rotation of the affected shoulder then compared with each other. Results: Mean ASES scores and Constant scores in double-row repair group improved more than single-row repair group significantly at 1year postoperatively. Muscle power of abduction and internal rotation, especially abduction power, improved more significantly in double-row repair group than in single-row repair. Conclusion: Arthroscopic double-row repair for the full thickness rotator cuff tear may be a superior technique, which showed better clinical outcomes and restoration of muscle power compared with single-row repair at relatively short period of postoperative follow-up. Restoration of footprint close to normal anatomy by double-row repair seems to play an important role in the recovery of muscle strength.

• 한국작물학회지
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• 제26권4호
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• pp.357-362
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• 1981

홍화증수를 위한 알맞는 재식밀도를 구명하고 그에 따를 수량 및 농업 형질의 변이를 조사하기 위하여 1980년 3월부터 10월30일까지 강원도 원주상지대학 실습포장에서 실험을 실시하여 얻은 결과를 요약하면 다음과 같다. 1. 초장은 휴폭과 주간이 좁을수록 커지는 것으로 나타났으며 이들 양자에 의해 영향을 받았다. 2. 주당 분지수는 휴폭과 주간이 좁아짐에 따라 감소하였으며 이를 양요인에 의해 영향을 받았다. 3. 지표면에서 제1분지까지의 높이는 주간에 의해 영향을 받으며, 좁을수록 그 위치가 높아졌다. 4. 초장은 휴폭과 부의 상관을 가지며, 초장과 제1분지까지의 높이는 휴폭x주간과 부상관을 갖는다. 또한 주당 분지수는 휴폭, 휴폭x주간과는 정상관, 초장과는 부상관을 보였다. 5. 수량은 주간, 휴폭x주간에 관하여 부상관을 가지며 제 1분지의 높이와는 정상관을 가졌다. 6. 수량은 주간에 의해 크게 영향을 받으며 다음은 주간xs휴폭이 영향하는 것으로 나타났다. 휴폭은 수량에 크게 영향하지 않으나 30cm 또는 40cm구가 가장 증수되었으며 주간은 5cm구가 가장 증수되어 30cm x 5cm구, 또는 40cm x 5cm구가 홍화의 증수를 위한 적철한 재식밀도인 것으로 나타났다.