• Korean Journal of Plant Tissue Culture
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• v.25 no.1
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• pp.69-74
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• 1998

The somatic embryos of Daucus carota L. cv. Hongshim developed in MS basal medium far 4 weeks had varied number of cotyledons. Palisade and spongy parenchyma of cotyledon were not clearly discriminated in all seedlings developed from the embryos. No independent existence of collateral vascular bundle was observed in all seedlings with various types of cotyledon ; instead, vascular bundles were either interconnected or partially connected with one another. Most of the cotyledonary bases on hypocotyl showed short cylinder structure which encircle plumule. The vascular tissues of cotyledonary bases and nodes of seedlings with jar-shaped or 1 cotyledon were connected in ring forms, showing the pattern of ectophloic shiphonostele, and similar ring form structure was also found in the vascular arrangement of 5 cotyledon seedlings. The vascular bundles of seedlings with 2, 3 and 4 cotyledons in many cases had independently arranged within the cotyledonary bases and nodes, showing the pattern of eustele. In hypocotyl, tetrarch or hexarch xylems prevailed in seedlings with jar-shaped cotyledon or 1 and 5 cotyledon; tetrarch xylems prevailed in 2 cotyledon seedlings; and triarch xylems prevailed in 3 cotyledon seedlings. In most of seedlings, cortex vascular bundles were dispensed in the region from cotyledonary node to hypocotyl, but double vascular bundles were also observed occasionally. In roots, diarch xylems were observed in most of seedlings with 2 cotyledons, triarch xylems in half of seedlings with 3 cotyledons, and diarch xylems in most of the remaining seedlings with the occasional occurrences of tetrarch xylems.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.1
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• pp.35-46
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• 2007

In the study digital imagery was used to examine asphalt concrete pavements. With digitally mastered-image information that was filmed with a video camera fixed on a car travelling on road at a consistent speed, a road surface management system that can gain road surface information (Crack, Rutting, IRI) was developed using an object-oriented language "Delphi". This system was designed to improve visualized effects by animations and graphs. After analyzing the accuracy of 3-D coordinates of road surfaces that were decided using multiple image orientation and bundle adjustment method, the average of standard errors turned out to be 0.0427m in the X direction, 0.0527m in the Y direction and 0.1539m in the Z direction. As a result, it was found to be good enough to be put to practical use for maps drawn on scales below 1/1000, which are currently producted and used in our country, and GIS data. According to the analysis of the accuracy in crack width on 12 spots using a digital video camera, the standard error was found to be ${\pm}0.256mm$, which is considered as high precision. In order to get information on rutting, the physically measured cross sections of 4 spots were compared with cross sections generated from digital images. Even though a maximum error turned out to be 10.88mm, its practicality is found in work efficiency.

• Archives of Reconstructive Microsurgery
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• v.19 no.1
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• pp.12-20
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• 2010

Purpose: Industrial punch accidents involving fingers cause segmental injuries to tendons and neurovascular bundles. Although multiple-level segmental amputations are not replanted to regain function, most patients with an amputated finger want to undergo replantation for cosmetic as much as functional reason. The authors describe four cases of digital amputation by an industrial punch that involved the reinstatement of the amputated finger involving a joint and neurovascular bundle. Amputated segments were replanted to restore amputated surfaces and distal segments. Methods: A single institution retrospective review was performed. Inclusion criteria of punch injuries requiring replantation were applied to patients of all demographic background. Injury extent (size, tissue involvement), operative intervention, pre- and postoperative hand function were recorded. Result: Four cases of amputations were treated at our institute from 2004 to 2008 from industrial punch machine injury. Average patient age was 32.5 years (25~39 years) and there were three males and one female. Sizes of amputated segments ranged from $1.0{\times}1.0{\times}1.2\;cm^3$ to $3{\times}1.5{\times}1.6\;cm^3$. Tenorrhaphy was conducted after fixing fractured bone of the amputated segments with K-wire. Proximal and distal arteries and veins were repaired using the through & through method. The average follow-up period was thirteen months (2~26 months), and all replanted cases survived. Osteomyelitis occurred in one case, skin grafting after debridement was performed in two cases. Because joints were damaged in all four cases, active ranges of motion were much limited. However, a secondary tendon graft enhanced digit function in two cases. The two-point discrimination test showed normal values for both static and dynamic tests for three cases and 9 mm and 15 mm by dynamic and static testing, respectively, in one case. Conclusion: Though amputations from industrial punch machines are technically challenging to replant, our experience has shown it to be a valid therapy. In cases involving punch machine injury, if an amputated segment is available, the authors recommend that replantation be considered for preservation of finger length, joint mobility, and overall functional recovery of the hand.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.3
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• pp.274-282
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• 1998

This study deals with sinking resistance for purse seine, in the case of different d/l, ratio of twine diameter and leg length. Experiments carried out on the six types simplified reduced model seines which were made of knotless netting. The nettings were woven in different leg length 4.3, 5.0, 5.5, 6.0, 6.6 and 7.7mm of polyester 28 tex two threads two -ply twine, and each of the seines were named I, II, III, IV, V and Ⅵ seine. Dimension of seine models were 450cm for corkline and 85cm for seine depth, each seines rigged up 160g of float for a floatline and 50g (underwater weight) of lead for a leadline. Experiments were measured in the observation channel of a flume tank at the static conditions Sinking motion was recorded by the two sets TV-camera for VTR which were placed in top and side of the model seine, and reading coordinate carried out by the video digitization system. An analysis were calculated out by simultaneous differential equations for numerical method by Runge - Kutta - Gill sub - routine. The results obtained were as follows: 1. Average sinking speed of seine of seine margin was fastest for Ⅵ seine followed by V, IV, III, II and I seines. 2. The coefficient of resistance for a seine wall was depended upon the ratio of d/l : KD =0.081 (d/l )-0.5 3. The coefficient of resistance for netting bundle was not depended upon the ratio of d/l :CR = 0.91 (), d : Twine diameter, l : Leg length, : Density of netting materals, $\omega$ : Density of water

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.919-930
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• 2014

In this study, the load capacities and behaviors of a shotcrete member with steel supports, as composite member, are investigated numerically by using a fiber section element. The cross section of a shotcrete lining with steel support is divided into a bundle of fibers, which are allocated nonlinear stress-strain relations and used for determining internal forces. To verify the used approach of the finite element method for shotcrete with steel supports, the load-displacement relations of shotcrete lining obtained by numerical analysis are compared with existing experimental results and are analyzed with the stress distribution of the shotcrete and steel support obtained numerically. As a result, it is shown that the proposed approach can predict the load capacities of each material and the overall nonlinear behavior of shotcrete lining with steel supports. The change of location of the neutral axis and the flexural resistance ratio of each material are also derived from the stress distribution of the cross section of the shotcrete lining with steel supports. From the results, it is concluded that the flexural resistance performance of steel support should be considered in shotcrete lining design.

• Journal of the Korean Vacuum Society
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• v.16 no.5
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• pp.377-382
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• 2007

In this study, we report the synthesis of the single-walled carbon nanotubes(SWCNTs) using laminated catalyst(Al/Fe/Al) layer deposited by sputter on Si(001). SWCNTs are grown by thermal chemical vapor deposition (TCVD) method. As the results of scanning electron microscopy(SEM), high resolution transmission electron microscopy(HR-TEM) and Raman spectroscopy, we confirmed the SWCNTs bundles with narrow diameter distribution of $1.14{\sim}1.32\;nm$ and average G&D ratio of 22.76. Compare to the sample having Fe/Al catalyst layer, it can be proposed that the top-aluminum incorporated with iron catalyst plays an important role in growing process of CNTs as a agglomeration barrier of the Fe catalyst. Thus, we suggest that a proper quantity of aluminium metal incorporated in Fe catalyst induce small and uniform iron catalysts causing SWCNTs with narrow diameter distribution.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.1
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• pp.9-18
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• 2013

Two-phase vapor-liquid flows exist in many shell and tube heat exchangers such as condensers, evaporators, and nuclear steam generators. To understand the fluid dynamic forces acting on a structure subjected to a two-phase flow, it is essential to obtain detailed information about the characteristics of a two-phase flow. The characteristics of a two-phase flow and the flow parameters were introduced, and then, an experiment was performed to evaluate the pressure loss in the tube bundles and the fluid-dynamic force acting on the cylinder owing to the pressure distribution. A two-phase flow was pre-mixed at the entrance of the test section, and the experiments were undertaken using a normal triangular array of cylinders subjected to a two-phase cross-flow. The pressure loss along the flow direction in the tube bundles was measured to calculate the two-phase friction multiplier, and the multiplier was compared with the analytical value. Furthermore, the circular distributions of the pressure on the cylinders were measured. Based on the distribution and the fundamental theory of two-phase flow, the effects of the void fraction and mass flux per unit area on the pressure coefficient and the drag coefficient were evaluated. The drag coefficient was calculated by integrating the measured pressure on the tube by a numerical method. It was found that for low mass fluxes, the measured two-phase friction multipliers agree well with the analytical results, and good agreement for the effect of the void fraction on the drag coefficients, as calculated by the measured pressure distributions, is shown qualitatively, as compared to the existing experimental results.

• Journal of the Korea Concrete Institute
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• v.22 no.2
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• pp.199-208
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• 2010

In order to substitute FRP bar for steel bar in new structures, it is necessary to establish a reliable design code. But relatively little research has been conducted on the material in Korea. So, a total of 22 beam specimens (18 GFRP reinforced concrete and 4 conventional steel reinforced concrete) were constructed and tested. In the first phase of the experiment, it was carried out to observe flexural behavior, and collect deflection and crack data. In order to eliminate of the uncertainty by the shear reinforcements and induce flexural failure mode, any stirrup were not used and only shear span-depth ratio were adjusted. However, almost beams were broken by shear and the ACI 440.1R, CSA S806, which were used to design test beams, showed considerable deviation between prediction and test results of shear strengths. Therefore in the second phase of the study, shear failure modes and behavior were observed. A standard specimen had dimensions of 3,300 mm long ${\times}$ 800 mm wide ${\times}$ 200 mm effective depth. Clear span and shear span were 2,800 mm, 1,200 mm respectively. Control shear span-depth ratio was 6.0. Four-point bending test over simple support was conducted. Variables of the specimens were concrete compressive strength, type and elastic modulus of reinforcement, shear span-depth ratio, effective reinforcement ratio, the effect of bundle placing method and cover thickness.

• Korean Journal of Heritage: History & Science
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• v.42 no.4
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• pp.4-19
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• 2009

Though admitting that, in light of the recent archaeological trend, the excavation on relics of Sam-gama (a sort of kiln steaming the hemp) is increasingly reported, little efforts by far have been made not only to restore its traditional structure design but also to research hardly the change of hemp-steaming technologies in ages. In this regard, this paper shows the exploration of structural method and design as well as operability with regard to Sam-gut, traditional hemp-processing equipment that was recently reconstructed in Jungsun, Kangwon Province. Samgut, generally positioned at the waterside area, is an traditional device for steaming hemp to get bast fibers from the raw material of hemp, principally consisting of HWA-JIP(fire-place) to obtain steams by feeding fire ad Mong-got(boiling chamber) to make the hemp steamed after stacking. More specifically, thick round-logs were piled at the bottom of Hwajip prior to stacking stones around its circumferential area. When the timber positioned below gets burned with high temperature to heat stones existing in the upper side, waters then poured onto it after laying a bundle of grass and soil up to the boiled stones. If so, there generates hot vapor, which is conveyed to Monggot to steam the hemp. Functionally, it is of outstanding importance that Samgut is capable of producing high-temperature water vapors instantaneously under the intensive manpower, thus being constructed achievable for those purposes. The Samgut made by digging the ground is an instant facility that is closed after use. The remains, which were used to generate higher thermal power for steaming hemp, make it hard to excavate the historic traits because there left little vestiges in the soil, which means keen attention must be paid to find out the trace of Smgama relics. Future research stall be focused on collection of broader data regarding Samgut including technological review in extracting bas fibers from the hemp.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.19 no.3
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• pp.1-11
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• 2024

Content is now recognized as a key resource to sustain competitive advantage in the OTT market and for e-commerce companies. Coupang is pursuing a content growth strategy to maximize the lock-in effect that binds consumers to the subscription economy and its ecosystem. Given this background, this study aims to explain Coupang's content growth momentum through a case study method and examine Coupang's content strategy in detail. Based on this, this study describes Coupang's content growth strategy in detail and confirms that Coupang differentiates its content from the competition by focusing on sports and low prices to build a lock-in effect in the subscription economy. As a result, we can summarize that the purpose of Coupang's content strategy is to build a lock-in effect for the subscription economy based on content differentiation focused on sports, a bundle strategy linked to e-commerce, and a low-cost strategy. This study contributes to the field of venture creation research by carefully analyzing how Coupang grew from a venture firm to a Decacorn corporation and developed the influence of its content in a completely different industry, and systematically explains the importance of content strategy in strengthening the lock-in effect for the subscription economy. Future research should compare the impact of content strategy of venture and startups in the contents industry to broaden the scope of research in the field and suggest deeper lessons learned.