• Journal of the Korean Wood Science and Technology
• /
• v.36 no.3
• /
• pp.1-8
• /
• 2008

The lateral strength test of bending type was done to investigate the lateral capacity of the double bolt connection of domestic larix glulam according to bolt spacing. In the shear specimen, which is bolted connection in the inserted plate type, the hole of bolt was made, changing the diameter of bolt (12 mm and 16 mm), the number of bolt (single bolt : control and double bolt), the direction of bolt row (in parallel to grain : Type-A and in perpendicular to grain : Type-B) and the bolt spacing (Type-A : 4 d and 7 d and Type-B : 3 d and 5 d). Lateral capacity and failure mode of bolt connection were compared according to conditions. In prototype design (KBCS, 2000), the reduction factor of the allowable shear resistance that the bolt spacing is reduced was calculated. The results were as follows. 1) Bearing stress per bolt in the single and double bolt connection of Type-A was directly proportional to bolt diameter and bolt spacing. Bearing stress of Type-B decreased as bolt diameter was increased, and decreased by 2~10% when bolt diameter was increased. 2) In the single bolt connection and the double bolt connection of Type-A, the splitted failure was formed in the edge direction. When the bolt spacing was 3 d in Type-B, bolt was yielded more in the part of tension than in the part of compression, and the splitted failure started at the bolt in the part of tension. In the 5 d spacing specimen, the bolt in the part of tension was yielded similarly to bolt in the part of compression, and the splitted failure started in the part of compression. 3) In the prototype design, the reduction factor was calculated by non-dimensionizing the yielding load in the standard of bolt spacing (Type A : 7 d and Type B : 5 d). In 12 mm bolt connection, the reduction factor of bolt spacing 4 d (type-A) and single bolt connection was 0.87 and 0.55, respectively, and the reduction factor of bolt spacing 3 d (Type-B) and single bolt connection was 0.91 and 0.55, respectively. In 16 mm bolt connection, the reduction factor of bolt spacing 4 d (type-A) and single bolt connection was 0.96 and 0.76, respectively, and the reduction factor of bolt spacing 3 d (Type-B) and single bolt connection was 0.91 and 0.77, respectively.

• Journal of the Korean Geotechnical Society
• /
• v.17 no.6
• /
• pp.5-14
• /
• 2001

This paper describes a simplified design method of stabilizing piles based on an experimental tests and an analytical study which can take into account the safety factor of slope and pile spacing. The nonlinear characteristics of the soil-pile interaction for stabilizing piles are modeled by using load transfer method. The interaction factors due to pile spacing and cap rigidity were estimated by using a three dimensional nonlinear finite element approach and laboratory tests. Based on the results obtained, the interaction factors are proposed quantitatively for one-row pile groups with spacing-to-diameter ratios varying far 2.5 to 7.0. The Bishop's simplified method of slope stability analysis is extended to incorporate the soil-pile interaction and determine the safety factor of the reinforced slope. Through the comparative study, it is found that the prediction by present approach is in relatively good agreement with the results of centrifuge tests and field tests and three dimensional finite element analyses.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.46 no.5
• /
• pp.407-410
• /
• 2001

This study was conducted to determine the optimal planting distance in cultivation of yacon (Polymnia sonchifolia Poeppig ＆ Endlicher). Plug seedlings were planted with 6 different plant densities of 80 $\times$ 60, 80 $\times$ 50, 70 $\times$ 50, 70 $\times$ 45, 70 $\times$ 40 and 60 $\times$ 45 cm. The plant height and the petiole length were increased with increasing the planting distance. The tallest plant height of yacon was 165.4cm with the plant density of 80 $\times$ 60 cm. However, branch number per plant, leaf number on main stem and stem diameter were not significantly difference among planting densities. Tuberous root was harvested 31.42 tons/ha in 70 $\times$ 50 cm spacing. The ratio of heavier tuberous roots than 200 g to total tuberous roots decreased significantly according to increase of planting density. Fresh weights of shoot and root, contain the crown bud, were decreased, as planting distance was shorter. Tuberous root number was fewer but its weight was heavier in wide planting than in dense planting. We think that optimal planting density is about 30,000 plants/ha, if it were to be 70 cm row spacing, intrarow spacing should calculate about 47cm.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.54 no.3
• /
• pp.148-154
• /
• 2005

Various methods for analyze optical components which are necessary before the fabrication of optical circuit component and as its applications, designing method of Wavelength Division Multiplexer(WDM) filter using arrayed-waveguide grating(AWG) is paper. In the case of analyzing uniform optical waveguide, effective index method(EIM), harmonic expansion method are used, and in the case of non-uniform optical waveguide, beam propagation method(BPM) are used. In this paper, to use arrayed-waveguide grating as WDM filter of centered wavelength of $1.55{\mu}m$ and wavelength spacing of 0.8nm, all of the parameter of AWG is calculated by the HEM and the BPM using EIM. As a result of calculation, free spectral range is 12.8nm, focal length $9336.55{\mu}m$, path difference $129.36{\mu}m$ and the number of slab waveguide 91 when the distance of core center to center on row land circle is $20{\mu}m$.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.3
• /
• pp.157-162
• /
• 2000

측발유동을 받는 일렬 군말뚝의 그룹효과를 파악하이 위해 3차원 유한요소해석을 수행하였다. 국내의 대표적인 화강풍화토 지반에 선단지지된 말뚝을 대상으로 측방으로 지반변위 발생시 말뚝 두부조건과 중심간격(2.5D, 5.0D, 7.0D, 단독말뚝) 및 말뚝주면의 접촉효과를 고려한 군말뚝의 상호작용계수를 산정하였다. 본 연구 결과, 단독말뚝과 비교하여 군말뚝의 간격이 좁아짐에 따라 상호작용계수는 현저하게 감소하였으며 말뚝 두부조건이 회전구속, 힌지,자유단의 순으로 감소정도가 크게 나타났다. 이는 실내모형실험을 통해 산정된 상호작용계수와도 비교적 잘 일치함을 보였다.

• Journal of Biosystems Engineering
• /
• v.20 no.3
• /
• pp.217-225
• /
• 1995

This study was conducted to find design factors of spraying device of the boom sprayer for low volume application. Four types of nozzles(standard flat nozzle, drift guard nozzle, even flat nozzle, and hollow cone nozzle) were used for the spray characteristic experiment. Spray patterns of the nozzles were distinguished by the nozzle type, spray distance, and spray direction. The flow rate was proportional to the square root of spray pressure in all nozzles. Increased nozzle height improved spray distribution at reduced pressures and/or increased spacing. Distribution tended to improve as pressure increased within the range of pressures used for fan nozzles.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2003.04a
• /
• pp.74-78
• /
• 2003

Stress analysis was conducted with finite element method to study the stress distributions in both single-pin and multi-pin loaded composite laminates. The various parameters involved in the design of the joint method were considered. The stress distributions in the vicinity of the holes were predicted considering the effects of various parameters such as the lay-ups, number of pins, number of rows, row spacing, and hole patterns. The results show that the performance of joint is greatly affected by these parameters.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1996.06c
• /
• pp.488-499
• /
• 1996

A propeller type mistblower was designed and manufactured. The machine consisted of a 770 millimeters diameter propeller driven by the power take off of a tractor. It delivered 26,400 cubic meters of air per hour and has the outlet speed about 180 kilometers per hour. Spray liquid was injected at 30 bars pressure through hollow cone type nozzles which were located around the air outlet of the machine bya poston type pump. Power consumption of the machine was found to be 12.46 kilowatts and the effective forward travel speed was about 2.7 kilometers per hour. Upon spraying mango trees, it was shown that the density of spray partices was about 100 microns and consumed 3.12 liters per tree. Working speed in 6 meters row spacing mango orchard was about one hectare per hour.

• Journal of Biosystems Engineering
• /
• v.27 no.6
• /
• pp.513-520
• /
• 2002

A 5-row walking garlic harvester with pulling mechanism was developed in the study, based upon a kinematical analysis and related preliminary field tests on the conventional garlic harvesting method. The harvesting efficiency of the developed harvester was more than 98% in the garlic field irrigated before harvesting, 80-85% in the field without irrigation. The harvesting performance of the harvester was 660∼825㎡/hr at the forward speed of harvester of 0.3m/s in the irrigated field before garlic harvesting. For proper garlic drying and collection, the harvester discharged the harvested garlic on the ground uniformly at the angles of 135。∼150。 to its forward direction with the garlic bulb's placing toward the harvester. In the field tests, it was recommended that the forward speed of the harvester be approximately less than 0.2m/s, and that the spacing of planting garlic seeds should be standardized in the future fur increasing its harvesting efficiency.

• Proceedings of the SAREK Conference
• /
• 2006.06a
• /
• pp.627-632
• /
• 2006

An experimental study is conducted to investigate the effect of the tube row and fin spacing on the air-side heat transfer and friction characteristics of fin-tube heat exchangers with slit fin pattern. A total of twelve samples of fin-tube heat exchangers with the nominal tube diameter of 7 mm, transverse tube pitch of 19 mm and longitudinal tube pitch of 12.5 mm are tested. The thermal fluid measurements are made using a psychometric calorimeter. The raw data are reduced to the desired heat transfer coefficient in terms of j-factor and friction factor of f for various frontal air velocities, fin pitches and number of tube rows.