• Korean Journal of Medicinal Crop Science
• /
• v.2 no.2
• /
• pp.146-148
• /
• 1994

The most important subject in cultivation of A. gigas NAKAI would be how to decrease the bolting rate. Belcause the decrease and poor of the yields and quality is imevitable in such field where the bolting rate is high. This study was carried out to investigate the time of flower-bud differentiation as a part of improvements of cultivation method. Shoot apex was fixed in Farmer's solution(ETOH 3:Acetic acid 1), thin paraffin ribbon was made, and the tissue was stained by Safranin solution. Differentiation time of flower-bud in A. gigas differed greatly from individuals by the seedling size, generally begun from middle of May to late of June, it was time that two leaves spread. In this results, Photoperiocid types of A. gigas NAKAI were regarded as LI type or LS type of dull-photosensitivity.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1993.03a
• /
• pp.41-48
• /
• 1993

The 2nd phase of Seoul Subway, Lines 5,6,7 and 8, is in progress. To reduce the surface traffic congestion during construction the greater part of the system has been engineered by bored tunnelling. The current tunnelling methodology is based on the New Austrian Tunnelling Method. Serveral collapses have been reported to date. Most of the collapses took place in the area forwed with soft ground. The modes and causes of the collapses were progressive failures in the unsupported surface and sliding failures due to the unfavourable joint direction. The major causes turned out to be the weakness of ground and the sudden influx of ground water from the surface. Some measures to prevent the failures are also presented. To ensure the safe tunnelling ghrough the soft ground the unsupported excavation area has to be minimized and closed as early as possible. Additional support measures such as supporting core, sealing shotcrete, forepoling, spread footing, face rock bolting and grouting should be employed as well depend on ground conditions.

• Korean Journal of Agricultural Science
• /
• v.35 no.2
• /
• pp.213-223
• /
• 2008

The instability of rock slopes caused by heavy rainfall and soil mass sliding needs the preventable and reinforcing method. The most important factor for the stability is the shear strength available in the planar part of the failure surface, which shows that a progressive failure takes place and a reinforcing of rock slope using FRP grout is effectively available. In this study, a grouting bolting interval predictions by limit equilibrium analysis and Matlab mathematical computer codes in several cases is presented for FRP reinforced rock slope. The proposed mathematical computer code can be easily applied for seeking properly FRP grout intervals prior to design and execute a reinforcement of a rock slope in practice.

• Korean Journal of Weed Science
• /
• v.16 no.4
• /
• pp.301-308
• /
• 1996

In this study, a propagation characteristics of green kyllinga(Kyllinga brevifolia var. leiolepsis H.) was investigated. Two to three rhizomes(1st rhizome) arised from the basal part of main shoot at 4th leaf stage and were grown to extend on the soil surface. Then new shoots(lst tillers) emerged from every node of the 1st rhizome. Second rhizomes also arised from the basal part of lst tiller at the time of 4th leaf openning. With such a regularity, 5th rhizomes and about 688 shoots were produced from one plant during one year-cultivation without competition under the natural condition. The degree of vegetative growth and seed formation was 3 times and 2.5 times higher in rhizomeoriginated plant than in that from seed, respectively. The amount of seed formation and the 1000 seeds weight was highest in one planted on June 1 and Aug. 1, respectively. Short-day treatment of less than 14hr appeared to be necessary for the induction of flowering and it was effective as treated not during germination but since at least 2 leaf stage of green kyllinga. Each shoot individually responded to short-day. When plants were exposed to short-day (9hr, day / 15hr, night) treatment at the stage of 2-3 leaves, more than 7 cycles were required for flowering induction. Bolting in main shoot occurred after emergence of 4 leaves under the short-day condition. Exogenous $GA_3$ slightly accelerated the velocity of bolting only in short-day condition.

• The Korean Journal of Ecology
• /
• v.14 no.2
• /
• pp.211-230
• /
• 1991

The germinatin of e. annuus continued from the middle ofmay to mid-october. The maximum germination occurred on the mid-july. The period bloom of was distingushed amongs the different growth forms ; a orm pr of biennial and a form of pr perennial flowering from the mid-may to mid-september, and a form ps biennial blossom from the beginning of October to earlynovember. the dispersal of seed for(a form pr)occurred from early June to the mid-september. A rotte, germinating from summer to autumn, could classified into several growth forms; individuals without a critical leaf area for bolting until september and October, become a form ps of biennial, whicth did not proceed toreproductive growth unitl the next year, even thought wintering. individuals flowered on 3 years after germination become a form pr of perennial. The growth formular of aform pr of bennial, grown in a pot was w=20.2[1+$3.36{\times}10^3$(-0.062t)]$^{-1}$. The maximum relative growth rate(rgr) was 0.062g/g/day and the maximum net assimlation rate(nar) 0.089g/g/day. Therelative growth among each organ was shown as R=0.12 $T^{1.15}$between the avove-ground part(t) and the below- ground part(r). the relation between the avove-ground part(t) and the ratio of stem weight(wi) was ws/wi=2.56 $T^{0.35}$. n.p.k. was largely distributed on a leaf throughoutthe total growth period. while growing, it tended to decrease on the vegetative organ gut vice versa on the reproductive organ. however, nitrogen was more widely distributed on a leaf then in the reproductive organ.

• Structural Engineering and Mechanics
• /
• v.10 no.3
• /
• pp.227-243
• /
• 2000

In a companion paper, tests on bolted side plated beams have shown that side plates can substantially increase the strength of existing reinforced concrete beams with little if any loss of ductility and, furthermore, induce a gradual mode of failure after commencement of concrete crushing. However, it was also shown that transverse interaction between the side plates and the reinforced concrete beam, that is vertical slip and which is a concept unique to side plated beams, is detrimental. Transverse interaction increases the forces on the bolt shear connectors and, hence, weakens the beam. It also reduces the ability of the composite plated beam to yield and, hence, to attain its full flexural capacity. The generic concept of transverse interaction will be described in this paper and the results used to develop a new form of rigid plastic analysis for bolted side plated beams which is illustrated with an application.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.3
• /
• pp.112-123
• /
• 2015

There are many systems for cutting plates or pipes into a desired shape. A typical system is a plasma cutter. It uses plasma, which means that an effective design of the table supporting the workpiece is an important issue in order to ensure a long operational career. Conventional roller-support worktables have a short lifespan due to scratches from the plasma, and it is also difficult to maintain the roller balance. By using a bolt-fastening method, deformation and failure of the final product can occur due to the stress concentration at bolting points. To escape these issues, a polygon support and bracket fastening method was designed. Due to polygons having a number of support surfaces, when one surface has been damaged, it is possible to reuse the support by utilizing a different surface. The bracket-fastening method can extend the worktable lifetime and increase productivity by reducing stress concentration. In this paper, the polygon support/bracket-fastening method is compared with existing technologies. Consequently, performance benchmarks are verified through a structure analysis and experimentation.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.1362-1369
• /
• 2007

Seoul Metro continuously converted the standard rail into continuous welded rail since the later part of 1990's, and currently, most of the sectors of the Seoul Metro are continuous welded rails. As the continuous welded rail is inhibited by the contraction and expansion force of the rail as well as rail-bed, this force is stored as the internal stress of the rail with the exception of portion of the both ends of the continuous welded rail. If the contraction and expansion of the rail is restricted, the internal stress, that is, the force in the direction of the axis, is proportional to the cross-sectional area of the rail. Therefore, with regards to the temperature changes, the internal stress changes in accordance with the type of rail, bolting apparatus, railroad tie and rail-bed. As such, the rail temperature becomes important data in securing the gap at the adjoining section of the rail in the standard rail section, and to determine the setting temperature for the continuous welded rail. In addition, it becomes basic data for maintenance of the track. Accordingly, this thesis introduces cases of installation of rail temperature detector in order to prevent and manage track defectiveness due to increase in rail temperature, and to utilize as basic data at the time of various construction and maintenance. Furthermore, this thesis aims to assist maintenance of track through systematic temperature management in the future by looking into means of its utilization.

• Tunnel and Underground Space
• /
• v.8 no.2
• /
• pp.118-129
• /
• 1998

A three dimensional boundary element method-BEAP3D was applied to the stability analysis of the mine openings not only to improve the stability during mining operations but also to serve the evaluation of the mine openings for further utilization. Stability analysis on the stability of the room-and-pillar stopes underneath of the old mine openings and the openings to be created by the newly proposed sublevel stoping method at the Nowhado Pyrophyllite Mine, showed that rock mass around the old and new stopes would be stable. Six stopes of a sublevel stoping designed for the Choongmu Limestone Quarry would be stable, too. A sublevel stoping method consisting of six stopes was similarly suggested for the Keumpyung Quartzite Mine. The stability can be guaranteed through out six stopes. Since mining starts from the bottom 1st sublevel to the uppermost sublevel, the safety of the stopes will improve together with the mining process. It would highly be recommended to investigate in-situ rock properties and the rock stresses for future studies. Even though the rock around the uppermost part and bottom of all the stopes have a very high factor of safety, spot reinforcements such as rock bolting would be recommended to mitigate the intermediate and minor principal stresses acting in a tensile mode.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.13 no.4 s.56
• /
• pp.116-125
• /
• 2009

Recently, modular system are popular in construction fields, and they are increasing their marcket share. To compare modular units, bolting and welding are most popular methods. However, the temperature around a welded part might be over than 1,300$^{\circ}C and the composite member might be exposed tp the direct welding heat about 20,000$^{\circ}C. This high welding heat makes decrease of the concrete strength. If the concrete strength seriously decreases, it can affect the behavior and safty of a structure. On this study, To prevent of concrete strength decreases by welding heat, we suggested method of to insert between steel and concrete.