• The Journal of Korea Robotics Society
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• v.19 no.2
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• pp.159-168
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• 2024

Lower limb amputees are increasing due to various reasons. It is difficult for lower limb amputees to walk without an assistive device such as a prosthetic leg. In this paper, an electronically controlled knee-type prosthetic leg with a 4-bar linkage structure for lower limb amputees was developed. The knee-type prosthetic leg has a 4-bar linkage structure and assists walking by using an integrated drive module. The torque is 90 Nm, the rotation speed is up to 120 deg, and it weight 1.9 kg, so it is lighter than a commercial prosthetic leg, so it can be used for a long time because there is less fatigue when walking. An integrated control board was developed by applying various sensors and microprocessor. The motor drive and encoder are built into the integrated drive module. The integrated control board and integrated drive module communicate using CAN. When a lower limb amputee wears a knee-type prosthetic leg and walks, it shows a shape similar to the swing phase graph of a normal people, and it is possible to walk naturally while walking.

• Journal of the Korean Society of Systems Engineering
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• v.13 no.1
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• pp.25-31
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• 2017

This paper aims to evaluate the conservatism in the design of APR1400 (Advanced Pressurized water Reactor 1400 designed by KHNP) reactor internals component, the LSS (Lower Support Structure). Re-engineering of the LSS is done based on the system design condition data and applicable ASME code that was used for the original APR1400 design. Systems engineering approach is applied to design the LSS of APR1400 without refering APR1400 LSS dimensional parameters and tries to verify important design parameters of APR1400 LSS as well as the validity of the re-engineering design process as independent verification method of reactor component design. Systems engineering approach applied in this study following V-model approach. The re-engineered LSS design showed more than enough conservatism for static loading case. The maximum deflection of LSS is under 1mm (calculated value is 0.25mm) from 4000 mm diameter of LSS. Hence the deflection can be ignored in other reactor internals for structural integrity assessment. Especially the effect of LSS deflection on fuel assembly can be minimized and which is one of the main requirements of LSS design. It also showed that the maximum stress intensity is 2.36MPa for the allowable stress intensity of 60.1 MPa. The stress resulted from the static load is also very small compared to the maximum allowable stress intensity, hence there is more than enough conservatism in the LSS design.

• Journal of Environmental Science International
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• v.10 no.1
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• pp.41-45
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• 2001

This study was carried out to investigate phytoplankton community structure in the Naktong river from January to December in 1999. In water quality, average value of pH were 8.1, BOD 2.5mg/$\ell$, COD 5.0mg/$\ell$, Chl-a 41$\mu\textrm{g}$/$\ell$, and $NH_4^+-N$ 0.08mg/$\ell$, respectively. Phytoplankton were identified 42 genera 76 species. Among these, diatoms were 39 species(51.3%), green algae 25 species(32.9%), cyanobacteria 4 species(5.3%), dinoflagellates 4 repectively. The highest standing crops were 33,023 cells/$m\ell$ in February at the Mulgum and the lowest 79 cells/$m\ell$ in March at the Goryung. Also, Standing crops were increased with proceeding from middle part to lower part. Seasonal succession of phytoplankton represented that Stephanodiscus hantzschii was dominant species in winter, Cyclotella menaghiniana and Synedra acus in spring, C. meneghiniana, S. acus, Aulacoseira granulata var. angustissima in summer, and A. granulata var. angustissima and C. meneghiniana in autumn. Ecological important species were 4 species, that are Stephanodiscus hantzschii, Cyclotella meneghiniana, Synedra acus, and Aulacoseira granulata var. angustissima. In the community analysis, dominance indices ranged from 0.434(August, Namji) to 0.999(January, February, Mulgum) and diversity indices from 0.026(February, Mulgum) to 3.073(September, Namji). According to the similarity index among the stations, it was generally defind as two areas such as middle(Goryung, Namji and Samryangjin) and lower part(Mulgum).

• Journal of Korean Association for Spatial Structures
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• v.12 no.3
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• pp.71-78
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• 2012

The dynamic behavior of spatial structures is different depending on the aspect ration of arch structure, as the rise-span ratio or open-angle, and these spatial structures show differently the character of seismic response in accordance with stiffness and connection of the lower support structures that are directly influenced by earthquake. Therefore, in this paper, dynamic analysis is conducted for seismic response of single layer arch structures by the influence of column's stiffness and connection, to reflect the different vertical and horizontal vibration mode of single layer arch structures. The vertical response of single layer arch structures is more influence by lower columns and the influence of column's connection rotational stiffness is not large, except to the hinged connections.

• Ocean and Polar Research
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• v.25 no.4
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• pp.519-528
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• 2003

Species composition and community structure of marine benthic community were studied in the intertidal zone of Jijindo Island, Gwangyang Bay. A total of 85 species of benthic marine plants including the 5 Cyanophyta, 9 Chlorophyta, 13 Phaeophyta, 56 Rhodophyta and 2 Magnoliophyta that were listed. The community structure was represented by Gelidium divaricatum in the upper zone, Celidium divalicatum and Ulva pertusa in the middle, and Ulva pertusa, Chondria crassicaulis, Chondracanthus intermedia and Sargassum thunbergii in the lower intertidal zone. The dominant species in the rnscro-zoobenthic community were Chthamalux challengeri in the upper and middle, Littorina brevicula between the upper and middle, and Mytilus edulis and Crassostrea gigas in the middle and lower intertidal zones. The economic benthic organisms such as Undaria pinnatifida, Mytilus edulis, and Crassostrea gigas found in the lower intertidal zone were frequently disturbed due to their collection by local resident. Therefore, it is necessary to record the correct information pertaining to these cases. The species diversity indices estimated kom different sources were quite different. They were 2.22 derived from frequency, 1.67 based on coverage, 2.17 based on sum of frequency and coverage and 2.04 derived from importance value. Species diversity and number of algal species in Gwangyang Bay have noticeably decreased, compared with their previously reported status. It is estimated that their decreases were caused by changes in the marine environment, especially pertaining to the polychaete community resulting from reclamation and dredging activity undertaken for the industrial development.

• 한국기계연구소 소보
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• s.16
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• pp.127-136
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• 1986

Recently deck crane of multi purpose cargo vessel (MPCV) is designed to posi¬tion in side instead of in the center line of the upper deck with a view to reduce the transportation cost and shipbuilding cost by shortening the length of ship. In this paper, the crane post was at first designed according to the crane maker’s specification and parent ship and the structure is analysed with Finite Ele¬ment Method. Through the careful reviews on the result of analysis, the final design of crane post was modified. The crane post is designed as a cylindrical in upper part and hexagonal in lower part instead of cylindrical on the whole as before. The connecting part of crane post is designed with the form of mixture of the cylinderical and hexagonal. Since the center of cylindrical and hexagonal section are not on the same line, it is expected to have the stress concentration. So, in order to attenuate the concentrated stress on the connecting part, the upper and lower parts was stiffened by inserting plate to enlarge the area of welding. The structure of deck part includes the tank side floor which is depend on the lower structure of the crane post that would support the force of the crane post by placing with 1.5 frame interval of the vertical plate.

• Journal of Conservation Science
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• v.37 no.1
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• pp.43-54
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• 2021

In this study, a scientific analysis of the gold leaf layers and internal structure of the Clay Seated Vairocana Buddha Triad in Seonunsa Temple, Gochang (Treasure No. 1752) was conducted. The surface of the Buddha statues is a gold foil, and the gold leaf layer consists of four layers. The gold leaf layer first composed on the molding clay was produced in the order of lacquer-fabrics-lacquer-gold foil. Subsequently, it was confirmed that the work was performed three times in the same way. The composition of the Buddha statues was divided into the head, body or upper body, lower body, and pedestal. The body was made in a cylindrical form by connecting vertically oriented wooden materials, and the head and lower body were also connected to the body in an empty form. Thus, the head, body, and lower body are grafted structures that are connected to a single Bokjang-gong. It was confirmed that the Clay Seated Vairocana Buddha Triad in Seonunsa Temple was made using wood materials for the basic form, after which the detailed form was created with molding clay, and the surface was finished with a process of layering gold foil and substances presumed to be lacquer.

• Journal of Environmental Impact Assessment
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• v.17 no.5
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• pp.279-288
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• 2008

Vertical forest distribution is one of the important factors to understand various ecological mechanism such as succession, disturbance and environmental effects. LiDAR data provide information, both the horizontal and vertical distribution of forest structure. The laser scanner survey provided a point cloud, in which the x, y, and z coordinates of the points are known. The objectives of this study were 1) to analyze factors of forest structure such as individual tree isolation, tree height, canopy closure and tree density using LiDAR data and 2) to compare the forest structure between outer and interior forest. The paper conducted to extract the individual tree using watershed algorithm and to interpolate using the first return of LiDAR data for yielding digital surface model (DSM). The results of the study show characters of edge such as more isolated individual trees, higher density, lower canopy closure, and lower tree height than those of interior forest. LiDAR data is to be useful for analyzing of forest structure. Further study should be undertaken with species for more accurate results.

• Earthquakes and Structures
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• v.7 no.6
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• pp.1141-1169
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• 2014

This study is aimed to investigate the seismic performance of low-rise precast wall system with base isolation. Three types of High Damping Rubber Bearing (HDRB) were designed to provide effective isolation period of 2.5 s for three different kinds of structure in terms of vertical loading. The real size HDRB was manufactured and tested to obtain the characteristic stiffness as well as damping ratio. In the vertical stiffness test, it was revealed that the HDRB was not an ideal selection to be used in isolating lightweight structure. Time history analysis using 33 real earthquake records classified with respective peak ground acceleration-to-velocity (a/v) ratio was performed for the remaining two types of HDRB with relatively higher vertical loading. HDRB was observed to show significant reduction in terms of base shear and floor acceleration demand in ground excitations having a/v ratio above $0.5g/ms^{-1}$, very much lower than the current classification of $0.8g/ms^{-1}$. In addition, this study also revealed that increasing the damping ratio of base isolation system did not guarantee better seismic performance particularly in isolation of lightweight structure or when the ground excitation was having lower a/v ratio.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.327-336
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• 2006

Site coefficients in IBC and KBC codes have some limits to predict the rational seismic responses of a structure, because they consider only the effect of the soil amplification without the effects of the structure-soil interaction. In this study, upper and lower limits of site coefficients are estimated through the pseudo 3-D elastic seismic response analyses of structures built on linear or nonlinear soil layers considering the structure-soil interaction effects. Soil characteristics of site classes of A, B, and C were assumed to be linear, and those of site classes of D and E were done to be nonlinear and the Ramberg-Osgood model was used to evaluate shear modulus and damping ratio of a soil layer depending on the shear wave velocity of a soil layer. Seismic analyses were performed with 12 weak or moderate earthquake records, scaled the peak acceleration to 0.1g or 0.2g and deconvoluted as earthquake records at the bedrock 30m beneath the outcrop. With the study results of the elastic seismic response analyses of structures, new standard response spectrum and upper and lower limits of the site coefficients of Fa and Fv at the short period range and the period of 1 second are suggested Including the structure-soil interaction effects.