• 한국가시화정보학회:학술대회논문집
• /
• 2007.11a
• /
• pp.123-127
• /
• 2007

The effect of axial slit wall of outer cylinder on Taylor-Couette flow was experimentally investigated. The axial slits were azimuthally located along the inner wall of outer cylinder and the number of slits was 6, 9 and 18. The radius ratio and aspect ratio of the experimental models was 0.825 and 48, respectively. We used PIV method to measure the flow field and applied refractive index matching method to resolve the image distortion due to the complex model geometry. The results showed the effect of slit on the flow transition is increased as the number of slit increased. When the model has 6 slits, there were hardly the effect of axial slit wall and the flow transition happened at the same Reynolds number of plain smooth wall model case.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.31 no.1
• /
• pp.84-90
• /
• 1986

An experiment was conducted to know the effects of planting dates (March 5, 15, and 25 and April 4) and transparent polyethylene (P.E.) film treatments(tunnel, tunnel slit, and mulch) on air and soil temperatures and growth and yield of a sweet corn variety, Great Bell. Maximum air and soil temperatures and minimum air and soil temperatures were greater at tunnel>tunnel slit>mulch in that order. Differences in maximum air and soil temperatures among the P.E. film treatments were much greater than those in minimum air and soil temperatures. However, when film was opened due to high air temperature over 40$^{\circ}C$ in the tunnel, air temperature was similar but soil temperature was lower com-pared to mulch. High temperature stress could be avoided in tunnel slit without opening film by increase in the number of slits. Cold damage of corn seedlings was avoided by tunnel and reduced by tunnel slit, and frost-damaged seedlings under the mulch were recovered in few days. The number of days from planting to silking was reduced as planting date delayed. At early plantings, tunnel enhanced early growth and silking, but it delayed at late plantings because tunnel was opened during the most of day time due to high temperature. Black streaked dwarf virus(BSDV) disease was more severe at early plantings and it was reduced in tunnel slit at late plantings because plants were grown under the film at the time of infection. The number of marketable ears was similar among all treatments except mulch at March 5 planting where BSDV was severely infected. Gross income was high in tunnel and tunnel slit at March 25 planting which had more larger marketbale ears and tunnel and tunnel slit at March 5 planting which had higher market price.

• Steel and Composite Structures
• /
• v.51 no.1
• /
• pp.93-101
• /
• 2024

This paper presents an experimental and analytical study on a steel slit damper designed as an energy dissipative device for earthquake protection of structures considering soil-structure interaction. The steel slit damper is made of a steel plate with a number of slits cut out of it. The slit damper has an advantage as a seismic energy dissipation device in that the stiffness and the yield force of the damper can be easily controlled by changing the number and size of the vertical strips. Cyclic loading tests of the slit damper are carried out to verify its energy dissipation capability, and an analytical model is developed validated based on the test results. The seismic performance of a case study building is then assessed using nonlinear dynamic analysis with and without soil-structure interaction. The soil-structure system turns out to show larger seismic responses and thus seismic retrofit is required to satisfy a predefined performance limit state. The developed slit dampers are employed as a seismic energy dissipation device for retrofitting the case study structure taking into account the soil-structure interaction. The seismic performance evaluation of the model structure shows that the device works stably and dissipates significant amount of seismic energy during earthquake excitations, and is effective in lowering the seismic response of structures standing on soft soil.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.5
• /
• pp.69-77
• /
• 2017

This paper introduces an optical encoder using the reflection in the slit. The digital optical encoder is a sensor to generate a pulse according to the displacement. An optical encoder is composed of 3 parts: light source, slit plate and light-receiving element. In a conventional encoder, one slit produces one signal. The resolution of the digital optical encoder is determined by the number of slits in the encoder plate. The small slit size is most important among the factors that determine the resolution in a generic-type optical encoder. However, a small slit has low productivity and technical difficulties, so analog optical encoders have emerged as an alternative. Nonetheless, this alternative requires additional circuitry and equipment because of the noise and drafts in the analog signals. A new sensor is presented in this paper with a high resolution and a slit of the same size using the reflection in the slit. Then, the path of the light that passes through the slit ccording to the shape was analyzed, and some paths were expressed in the mathematical expressions. In addition, the optical paths were analyzed in the rectangular, octagonal, and circular encoders, and shown the obtained number of signals per slit by using them. Thus, we confirm that this method has the best performance in circle-shaped slits.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.37 no.3
• /
• pp.105-112
• /
• 2009

This study has attempted to facilitate various new technologies related to indoor containers and develop a desirable planting environment after investigating the growth (including root growth) of shade-tolerant landscape plants under slit processing, a natural indoor ventilation system. The following results were found: In terms of the shoot growth of Fatsia japonica in a slit container, no distinctive difference was observed in comparison with the control group. However, growth was good when the container 250mm tall or taller. Therefore, it was verified that optical soil depth is more important than slit processing in shoot growth of Fatsia japonica. In Fatsia japonica root length was observed as follows: Control 2(250mm) > Slit 2(250mm) > Control 1(195mm) > Slit 3(360mm) > Control 3(360mm) > Slit 1(195mm). The largest growth was observed in Control 2(250mm), which had no slit processing. In term of root width, this was lower than the initial value in all groups, which means that the root grew vertically, not horizontally. In terms of plant height of Ophiopogon japonicus, a gradual increase was observed in the control group that had no slit processing. No significant growth was detected in the slit system, however. In terms of shoot number, slit containers were generally higher than the control group. In terms of fresh and dry weights, on the contrary, slit containers were mostly lower than the control group. In Ophiopogon japonicus, root length was observed as follows: Slit 2(250mm) > Slit 1(195mm) > Control 2(250mm) > Control 3(360mm) > Slit 3(360mm) > Control 1(195mm). In Ardisia japonica, slit containers were mostly greater than control group in terms of plant height. The greatest plant height was observed at Slit 2(250mm) instead of Slit 1(195mm) and Slit 3(360mm). Except for plant height and shoot number, however, no significant shoot and root growth was observed. Root length was observed as follows: Slit 2(250mm) > Slit 3(360mm) > Control 3(360mm) > Slit 1(195mm) > Control 2(250mm) > Control 1(195mm). Therefore, root length in slit containers was mostly greater than in the control group. The width of root, however, declined in general.

• KIEAE Journal
• /
• v.8 no.2
• /
• pp.59-64
• /
• 2008

This research was performed to activate various new technology for indoor container, and attempt to a desirable planting environment of indoor plant by verify effect that indoor container slit ventilation system gets in growth and root activation of Korea Native Plants. Main result is as following. 1. Davallia mariesii, typical epiphyte fern, was appeared that growth of top and root activation was helped by slit ventilation system in indoor container and were very positive in rhizome development specially. 2. Hedera rhombea was helped growth of top by slit ventilation system, and specially, effect of plant height and number of shoot. Also, this slit system was positive in root activation. So, this indoor container appeared by thing which is very desirable in climbing plants as well as epiphyte plants. According to result that see effect getting in growth and root activation of Davallia mariesii and Hedera rhombea for indoor container slit ventilation system, Growth of top was different in plant but root activation was developed.

• Steel and Composite Structures
• /
• v.26 no.3
• /
• pp.289-301
• /
• 2018

The rigid steel connections were suffered severe damage because of low rotational capacity during earthquakes. Hence, many investigations have been conducted on the connections of steel structures. As a solution, steel slit dampers were employed at the connections to prevent brittle failure of connections and damage of main structural members. Slit damper is a plate or a standard section with a number of slits in the web. The objective of this paper is to improve the seismic performance of steel slit dampers in the beam-to-column connection using finite element modeling. With reviewing the previous investigations, it is observed that slit dampers were commonly fractured in the end parts of the struts. This may be due to the low participation of struts middle parts in the energy dissipation. Thus, in the present study slit damper with elliptic slits is proposed in such a way that end parts of struts have more energy absorption area than struts middle parts. A parametric study is conducted to investigate the effects of geometric parameters of elliptic slit damper such as strut width, strut height and plate thickness on the seismic performance of the beam-to-column connection. The stress distribution is improved along the struts in the proposed slit damper with elliptic slits and the stress concentration is decreased in the end parts of struts. The average contributions of elliptic slit dampers, beam and other sections to the energy dissipation are about 97.19%, 2.12% and 0.69%, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.31 no.10
• /
• pp.889-894
• /
• 2007

The effect of the axial slit of outer cylinder on Taylor-Couette flow was experimentally investigated. The radius ratio and aspect ratio of the model was 0.825 and 48, respectively. The depth of slits was 5mm and total 18 slits were azimuthally located along the inner wall of outer cylinder. We used PIV method to measure the flow field and applied refractive index matching method to resolve the image distortion due to the complex model geometry. The results showed the axial slit did not affect the transition from laminar Couette flow to Taylor vortex. The effect of slit wall appeared when the Reynolds number is larger than Re=143 and the slit model shows the transition to turbulent Taylor vortex flow above Re=143.

• Korean Journal of Heritage: History & Science
• /
• v.45 no.4
• /
• pp.4-21
• /
• 2012

Jade ornaments, which include slit earrings, scoop-shaped objects and tubular beads have been extensively identified in Northeast Asia, such as Korea, China, Japan and the Maritime Province of Siberia. Among them slit earrings are distributed in the whole area of Northeast Asia. Although this object shows the typological differences in accordance with the excavated region in detail, all of them are characterised by the slit on the centre of jade ring. The buried context and the shape of this object suggest that this artefact was the earring; thus it is named to 'slit earring'. Most of slit earrings of the Neolithic Age concentrate in Northeast China and the areas south of the Yangtze River, and the Japanese Archipelago. However, unfortunately, Slit earrings, which were produced in the tradition of the incipient and early phases of the Neolithic Age in Northeast Asia, have not been excavated in the Korean Peninsula. The number of slit earrings reported so far is eight, and especially until the 20th century, almost none was reported with its exact excavation location and only three of them are known as excavated through surface surveys and preliminary excavations. However, from the beginning of the 21st century onwards, the number of discovered slit earrings is increasing. Particularly, five pieces of this object uncovered in the 21st century are discovered in the official excavation; thus the exact archaeological context such as buried locations and chronologies could be estimated. By considering the buried context, slit earrings are associated with stone axes, which were produced in the incipient and early phase of the Neolithic Age in the Korean Peninsula. In addition, considering the number of unearthed objects is a few, it could be postulate that slit earring was the artefact that only a few persons, who had a special role in the society, could possess. However, slit jade earrings that have been excavated in the Korean Peninsula are extremely low in their number compared to the cases of its neighbouring countries such as China and Japan, and the researches on this subject have not been much conducted in Korea. Therefore, it is my supposition that slit earrings, which have been discovered in the Korean Peninsula, might be the imported item from the nearby areas. Particularly, the Southern Coast was closely connected with Japanese Islands and the Eastern Coast was interchanged with Northeast China or the Maritime Province of Siberia. Considering that excavations and researches on the Neolithic remains in the Korean Peninsula have not been sufficiently and actively conducted, it could be expected that the further investigations and researches will reveal the sufficient quantities of slit earrings in near future.

• International Journal of Fluid Machinery and Systems
• /
• v.5 no.2
• /
• pp.60-64
• /
• 2012

The helical flow regime was investigated by using DPIV when the rotating Reynolds number is small. The wall slits were azimuthally located along the inner wall of outer cylinder and the slits number of each model was 9 and 18, another plain wall model was also studied for comparison purpose. The helical vortex flow regime can be observed in all the three models. The negative temperature gradients determine the direction of the rotation and movement of the helical vortex. But the helical wavy vortex flow can only be found in the plane and 9-slit models. And the result showed that the existence of slit wall accelerated the transition process.