• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.10a
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• pp.138-143
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• 2001

Based on mild slope equation and parabolic approximation the forward diffraction of monochromatic waves by a straight breakwater are studied numerically. The characteristics and effects of stem wave along breakwater and the relations between the stem wave and incident wave angle are discussed.

• Journal of the Korean Wood Science and Technology
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• v.11 no.1
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• pp.5-11
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• 1983

This paper aims at gaining the informations atout the fibril angle at secondary walls of tracheids. The test specimens were taken from disks on stem wood of "Pinus koraiensis Sieb. et zucc". The method of measuring the fibirl angle was selected so-called "iodine method" that crystalline aggregates of iodine may be induced to form within the elongated interstices of the cellulose matrix of the secondary wall and that these elongated crystals are oriented parallel to the long axies of the fibrills of cellulose. The following conclusions may be drawn from the results of this investigation. 1) Gross average fibril angle was about $17.6^{\circ}$ on stem wood. 2) Its values seem to be greater for earlywood (avg.$19.8^{\circ}$) than for latewood tracheids (avg.$15.3^{\circ}$) in normal wood. 3) According to the increase of annual ring from pith to barks the orientation of fibril angle seems to be decrease gradually in normal wood. 4) In the case of height variation in trees the sample trees have a tendency to increase the orientation fibril angle to the increase of tree height in stem.

• Journal of Korean Neurosurgical Society
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• v.44 no.6
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• pp.401-404
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• 2008

Primary intracranial squamous cell carcinoma is extremely rare, with most cases arising from a preexisting benign epidermoid cyst. We report a rare case of primary intracranial squamous cell carcinoma in the brain stem with a cerebellopontine angle (CPA) epidermoid cyst. A 72-year-old female suffered from progressive left hemiparesis, difficulty in swallowing, and right hemifacial numbness. Diffusion-weighted magnetic resonance imaging revealed a high signal intensity (SI) lesion in the CPA region and an intra-axially ring-enhanced cystic mass in the right brain stem with low SI. Whole-body positron emission tomography showed no evidence of metastatic disease. The histological findings revealed a typical epidermoid cyst in the CPA region and a squamous cell carcinoma in the brain stem. We speculate that the squamous cell carcinoma may have been developed due to a chronic inflammatory response by the adjacent epidermoid cyst. The patient underwent a surgical resection and radiotherapy. After 12 months, she had no evidence of recurrence.

• Journal of the Korean Wood Science and Technology
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• v.33 no.1 s.129
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• pp.21-28
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• 2005

Tracheid length and width, microfibril angle, compressive, bending, and impact strengths between the south and north sides of stem pith in Larix kaemferi were measured. Sample trees were 30 years old which had planted in the central region of Korea. In general, there were no difference in the tracheid length and width, microfibril angle, and strengths between the two sides. And no difference in tangential shrinkage and strengths between the two sides was thought to be due to identical microfibril angle between the two sides.

• Journal of Ocean Engineering and Technology
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• v.17 no.5 s.54
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• pp.25-31
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• 2003

Numerical experiments have been conducted using the nonlinear combined refraction-diffraction model, in order to analyze the generation characteristics of stem wave, which is formed by the interaction between vertical structure and the oblique incident waves. The results of stem wave are discussed through the stem wave height distribution along/normal vertical structure, under the wide range of incident wave conditions-wave heights, periods, depths, and angles. Under the same wave height and period, the larger the incident wave angle, the higher the stem wave heights. According to the results of wave height distribution, in front of vertical structure, the maximum of stern wave heights occurs in the location bordering the vertical wall. Furthermore, the most significant result is that stem waves occur under the incident angles between $0^{\circ}\;and\;30^{\circ}$, and the stem wave height ratio has the maximum value, which is approximately 1.85 times the incident wave height when the incident wave angle becomes $23^{\circ}$.

• Journal of Advanced Research in Ocean Engineering
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• v.2 no.2
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• pp.67-80
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• 2016

The resistance performance of an icebreaking cargo vessel with varied stem angles is investigated numerically and experimentally. Ship-ice interaction loads are numerically calculated based on the fluid structure interaction (FSI) method using the commercial FE package LS-DYNA. Test results obtained from model testing with synthetic ice at the Pusan National University towing tank and with refrigerated ice at the National Research Council's (NRC) ice tank are used to validate and benchmark the numerical simulations. The designed icebreaking cargo vessel with three stem angles ($20^{\circ}$, $25^{\circ}$, and $30^{\circ}$) is used as the target ship for three concentrations (90%, 80%, and 60%) of pack ice conditions. The comparisons between numerical and experimental results are shown and our main conclusions are given.

• Journal of Biosystems Engineering
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• v.41 no.3
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• pp.201-207
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• 2016

Purpose: A water-spraying type automatic glochids removal system for cactus (Opuntia humifusa) stem was developed, and its performance was evaluated. The system was developed to reduce intensive human labor in removing glochids from cactus stem skin without inducing damage prior to further processing into value-added products. Methods: The developed system consists of conveyor and water-spraying systems. The conveyor system delivers cactus stems through water-spraying compartments and finally to a collecting box. In order to remove the glochids, rotating nozzles spray water over all areas (i.e., front and back faces and sides) of the cactus skin under controlled water pressure. Operating conditions such as conveyor speed, water pressure, angle of water-spraying nozzles, distance between conveyor belt and rotating nozzles, and angle of cactus flipping slide were adopted from our previous study and applied on the system design and manufacturing. The performance of glochids removal was evaluated by counting the number of glochids on the cactus stem before and after processing on the system. Results: The developed system performed efficiently and effectively under the pre-studied operating conditions except for the angle of cactus flipping slide. The new system had a glochids removal ratio of 94.1% without damaging the cactus skin. Considering the original number (approximately 30-60) of glochids, the remaining number was low (1-4), and most of them were found at the side edge of the cactus stem. This system can remove glochids from 360 cactus stems in 1 hr regardless of cactus size. Conclusions: The performance of the new system in glochids removal without damaging cactus skin is superior to any other existing device (i.e., brush type, rubber-friction type, and agitation type). The system is expected to be applied in cactus (O. humifusa) processing facilities.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.2
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• pp.111-118
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• 2006

It is indispensable to grasp the turning ability of a ship to operate her effectively. For this purpose, the author measured the turning ability of training ship, A-RA by use of bow thruster and stem rudder. The turning ability of this ship, in case of using both of stem rudder and bow thruster at the same time, caused by increase of steering angle provides more influence to the size of tactical diameter than it caused by the power of bow thruster. But the influence of bow thruster on the turning ability is available only within rudder angle $5^{\circ}\;-\;10^{\circ}$, so it is possible to grasp that the effect of bow truster is reduced as rudder angle become bigger. In case of the influence of bow thruster by her speed, the ability of bow thruster is very effective at low speed, but it is almost not available in normal turning speed. Therefore, the using both of stem rudder and bow thruster can be useful in case of low speed proceeding at entrance or departure of the narrow waterway or inside port which sea traffic is congest for collision avoidance.

• Journal of Biosystems Engineering
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• v.25 no.6
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• pp.511-516
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• 2000

The strength of the connecting joint of boxthorn(Lycium chinense Mill) fruits to tree twigs was determined experimentally at several pulling angles(0$^{\circ}$, 15$^{\circ}$, 30$^{\circ}$,45$^{\circ}$and 60$^{\circ}$) and at different harvesting seasons from August to November 1999 using an universal testing machine. The detachment force of mature fruits of boxthorn decreased as the pulling angle increased and varied with the harvesting season. The detachment force however did not gradually decreased as the harvesting season advanced due to difference of maturity of fruits from one harvesting season to another. Among three varieties of boxthron Cheongyang gugija Cheongyang native and Cheongyang ＃2, the maximum detachment force was 1.24 N at the pulling angle of zero degree. The highest detachment forve(1.29 N) of mature fruits of boxthorn appeared at the harvesting season of August, 1999.

• Journal of Korea Foresty Energy
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• v.18 no.1
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• pp.1-5
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• 1999

Variations in the wood quality were analyzed to utilize Korean pine (Pinus koraiensis S. et Z.) efficiently and to develop suitable use, depending on the stem location. Variations in the tracheid length and width, microfibril angle, compression strength were measured at the heights of 0.3, 1.3, 2.3, and 5.3m in the longitudinal direction of the 20m pine and they were analyzed by Duncan`s multiple range test. Variations in the tracheid length, width and compression strength did not show significant difference, whereas those in the microfibril angle showed significant difference. However, the microfibril angle did not vary with the height of trees, showing inconsistent pattern in change.