• Journal of the Korean Institute of Landscape Architecture
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• v.16 no.2
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• pp.1-7
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• 1988

Predicting treeform should be very important, eventhough it is difficult, step for landscape designers. This study was carried out to develop a method to classify the treeforms of landscape plants by numerical data. Twenty five treeforms are selected to be compared with 41 Zelkova serrata MAKINO, 26 Pinus strobus L., and 44 Magnolia denudata DESROUX. Statistical judgement was made by using X$^2$-Test. The results are summerized as follows. 1. Zelkova serrata was classified as B3 or C3. This species showed a tendency of changing from A type to B or C type, and the CL/CH ratio(canopy length/canopy height) is thought to be increased as aged. 2. pinus strobus was classified as D4-D5 and the CL/CH ratio tends to be increased as aged. 3. Magnolia denudata was classified as D4 and the change by aging was not observed clearly.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.5
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• pp.91-99
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• 1998

The widespread use of thin shell structures has created a need for a systematic method of analysis which can adequately account for arbitrary geometric form and boundary conditions as well as arbitrary general type of loading. Therefore, the stress and analysis of thin shell has been one of the more challenging areas of structural mechanics. A wide variety of numerical methods have been applied to the governing differential equations for spherical and cylindrical structures with a few results applicable to practice. The analysis of axisymmetric spherical shell is almost an every day occurrence in many industrial applications. A reliable and accurate finite element analysis procedure for such structures was needed. Dynamic loading of structures often causes excursions of stresses well into the inelastic range and the influence of geometry changes on the response is also significant in many cases. Therefore both material and geometric nonlinear effects should be considered. In general, the shell structures designed according to quasi-static analysis may fail under conditions of dynamic loading. For a more realistic prediction on the load carrying capacity of these shell, in addition to the dynamic effect, consideration should also include other factors such as nonlinearities in both material and geometry since these factors, in different manner, may also affect the magnitude of this capacity. The objective of this paper is to demonstrate the dynamic characteristics of spherical shell. For these purposes, the spherical shell subjected to uniformly distributed step load was analyzed for its large displacements elasto-viscoplastic static and dynamic response. Geometrically nonlinear behaviour is taken into account using a Total Lagrangian formulation and the material behaviour is assumed to elasto-viscoplastic model highly corresponding to the real behaviour of the material. The results for the dynamic characteristics of spherical shell in the cases under various conditions of base-radius/central height(a/H) and thickness/shell radius(t/R) were summarized as follows : The dynamic characteristics with a/H. 1) AS the a/H increases, the amplitude of displacement in creased. 2) The values of displacement dynamic magnification factor (DMF) were ranges from 2.9 to 6.3 in the crown of shell and the values of factor in the mid-point of shell were ranged from 1.8 to 2.6. 3) As the a/H increases, the values of DMF in the crown of shell is decreased rapidly but the values of DMF in mid-point shell is increased gradually. 4) The values of DMF of hoop-stresses were range from 3.6 to 6.8 in the crown of shell and the values of factor in the mid-point of shell were ranged from 2.3 to 2.6, and the values of DMF of stress were larger than that of displacement. The dynamic characteristics with t/R. 5) With the thickness of shell decreases, the amplitude of the displacement and the period increased. 6) The values of DMF of the displacement were ranged from 2.8 to 3.6 in the crown of shell and the values of factor in the mid-point of shell were ranged from 2.1 to 2.2.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.3
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• pp.113-121
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• 1998

The widespread use of thin shell structures has created a need for a systematic method of analysis which can adequately account for arbitrary geometric form. Therefore, the stress analysis of thin shell has been one of the more challenging areas of structural mechanics. The analysis of axisymmetric spherical shell is almost an every day occurrence in many industrial applications. A reliable and accurate finite element analysis procedure for such structures was needed. In general, the shell structures designed according to quasi-static analysis may fail under conditions of dynamic loading. For a more realistic prediction on the load carrying capacity of these shell, in addition to the dynamic effect, consideration should also include other factors such as nonlinearities in both material and geometry since these factors, in different manner, may also affect the magnitude of this capacity. The objective of this paper is to demonstrate the dynamic characteristics of spherical Shell. For these purpose, the spherical shell subjected to uniformly distributed step load was analyzed for its large displacements elasto-viscoplastic dynamic response. The results for the dynamic characteristics of spherical shell in the cases under various conditions of base-radius/central height(a/H) and thickness/shell radius(t/R) were summarized as follows: 1. The dynamic characteristics with a/H, 1) As the a/H increases, the amplitude of displacement increased. 2) The values of displacement Dynamic Magnification Factor (DMF) range from 2.9 to 6.3 in the crown of shell and the values of factor in the mid-point of shell range from 1.8 to 2.6. 3) As the a/H increases, the values of DMF in the crown of shell is decreased rapidly but the values of DMF in mid-point of shell is increased gradually. 4) The values of DMF of hoop-stresses range from 3.6 to 6.8 in the crown of shell and the values of factor in the mid-point of shell range from 2.3 to 2.6, the values of DMF of stress were larger than that of displacement. 2. The dynamic characteristics with t/R, 1) With the decrease of thickness of shell decreses, the amplitude of the displacement and the period increased. 2) The values of DMF of the displacement were range from 2.8 to 3.6 in the crown of shell and the values of factor in the mid-point of shell were range from 2.1 to 2.2.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.6
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• pp.394-404
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• 2013

In the present study, the characteristics of spectral peakedness parameter $Q_p$, bandwidth parameter ${\varepsilon}$, and spectral width parameter ${\nu}$ were analyzed as a first step to define the swell waves quantitatively. For the analysis, the joint probability density function of significant wave heights and peak periods were newly developed. The MCMC(Markov Chain Monte Carlo) simulations have been performed to generate the significant wave heights and peak periods from the developed probability density functions. Applying the simulated significant wave heights and peak periods to the theoretical wave spectrum models, the spectral shapes parameters were obtained and analyzed. Among the spectral shape parameters, only the spectral peakedness parameter $Q_p$, is shown to be independent with the significant wave height and peak wave period. It also best represents the peakedness of the spectral shape, and henceforth $Q_p$ should be used to define the swell waves with a wave period. For the field verification of the results, wave data obtained from Hupo port and Ulleungdo were analyzed and results showed the same trend with the MCMC simulation results.

• Korean Journal of Applied Biomechanics
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• v.19 no.2
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• pp.399-406
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• 2009

The purpose of this study was to compare the effect of wearing roller shoes and jogging shoes on kinematic characteristics in lower extremity during walking. Eight male middle school students(age: $15.0{\pm}0.0^{\circ}$ yrs, height $175.9{\pm}6.6cm$, weight: $616.3{\pm}84.9$ N) who have no musculoskeletal disorder were recruited as the subjects. Temporal parameters, step length, stride length, center of mass, velocity of CM, angle of segment, angular velocity and range of motion were determined for each trial. For each dependent variable, paired t-test was performed to test if significant difference existed between shoe conditions(p < .05). The results showed that stride length and velocity of CM in wearing roller shoes were significantly less than those found in wearing jogging shoes. These indicated that walking patterns may be changed by different shoe conditions and unstable braking condition because of wheel. Angle of ankle joint at LHC1 and LHC2 in wearing roller shoes was greater than the corresponding value for wearing jogging shoes. It seems that the ankle joints are locked in an awkward fashion at the heel contact to compensate for imbalance. Otherwise, dorsi flexion was not produced at the heel contact point in wearing roller shoes.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.6
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• pp.25-34
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• 2012

New calibration method for the near-field scanning (NFS) system is presented. The proposed calibration method consisted of a new near-field antenna (NFP) and newly devised patterns as circular patch patterns (CPPs) and meander patterns (MPs). The proposed patterns were used for improving spatial resolutions and simplifying a calibration procedure of the NFP compared to the conventional method defined in the IEC61967-3 and 6. Also, the effect of the length of NFPs on attenuation characteristics was investigated with length of 8mm and 30mm. For them, we designed and fabricated CPPs of diameter (D) = 20, 40, 60, and 100mm and MPs of various widths and spaces. We found the reverse relations between spatial resolutions and heights of measuring points by using simplified calibration procedure. The testing result shows that the spatial resolution of $120{\mu}m$ at height of $200{\mu}m$ was verified without complex correlation algorithms under 8GHz. For manufacturing cost all patterns and the NFP were realized with low-cost fabrication using PCB (FR-4) not by a conventional LTCC process. For verification of chip-level EMC from the results, near-field scanning system (NFSS) having step resolution of Sub-micron scale was produced and by using the proposed NFSS and proposed NFP measurement of chip shows accurately the shape of the resolution of $200{\mu}m$ patterns for securing a high level of chip-level EMC verification.

• Journal of Forest and Environmental Science
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• v.13 no.1
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• pp.66-80
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• 1997

Pinus koraiensis is one of the major speciese which have been recently planted for ten years and consists of 31% of total plantation. Presently young stand less than 30 years consists of 87% of total forest, but tending thinning of it is hardly carried out and the desirable direction for the thinning is not established yet. The objective of the study is to introduce the optimum thinning plan and thinning method through the long-run experiment of tending thinning for the Pinus koraiensis stand. The experiments carry out to interprete its growth model on the subject of two thinning experimental plots and yield table of Pinus koraiensis. As the basic step for understanding the thinning process, a theoretical growth model which is suitable to express the growth process is required. For that purpose, three growth functions (Mitscherlich, 4 parameter Richards, 3 parameter Richards) are applied to the diameter growth of the sample trees which are taken in the two plots. The results show that 3 parameter Richards is the most suitable. It is also verified that the diameter growth, the height growth, and the decrease in the number of stocks can be estimated by this function. To estimate the growth change of single tree, growth model including parameter h which is related to the occupation area of single tree are introduced. The parameter h can be estimated by using the data of the diameter growth obtained from the established experimental plots. Therefore, if both verification and modification of the usefulness of the model suggested is made, equations which tell about the thinning effects could be drived by estimating the growth process of single tree in advance.

• Journal of Korea Water Resources Association
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• v.48 no.6
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• pp.425-438
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• 2015

The objective of this study was to evaluate simulation of agricultural water supply considering yearly variation of irrigation efficiency. The water supply data of the Idong reservoir from 2001 through 2009 was collected and used for this study. Total 6 parameters including irrigation efficiency (Es), drainage outlet height, and infiltration, were used for sensitivity analysis, calibration, and validation. Among the parameters, the Es appeared to be the most sensitivity parameter. The Es was calibrated on a yearly basis considering sensitivity and time-varying characteristic, while other parameters were set to fixed values. The statistics of percent bias (PBLAS), Nash-Sutcliffe efficiency (NSE), and root means square error to the standard deviation of measured data (RSR) for a monthly step were 2.7%, 0.93, and 0.26 for the calibration, and 3.9%, 0.89, and 0.32 for the validation, correspondently. The results showed a good agreement with the observations. This implies that the modeling only with appropriate parameter values, apart from modeling approaches, can simulate the real supply operation reasonably well. However, the simulations with uncalibrated parameters from previous studies produced poor results. Thus, it is important to use calibrated values, and especially, we suggest the Es's yearly calibration for simulating agricultural water supply.

• Journal of Korea Water Resources Association
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• v.41 no.3
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• pp.305-314
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• 2008

Urban sewer systems are designed to operate in open-channel flow regime and energy loss at circular manholes are usually not significant. However, the energy loss at manholes, often exceeding the friction loss of pipes under surcharge flow, is considered as one of the major causes of inundation in urban area. Therefore, it is necessary to analyze the head loss associated with manholes, especially in surcharge flow. Hydraulic experimental apparatus which can be changed the invert type(CASE A, B, C) and step height(CASE I, II, III) was installed for this study. The range of the experimental discharges were from $1.0{\ell}/sec$ to $5.6\;{\ell}/sec$. As the manhole diameter ratio($D_m/D_{in}$) increases, head loss coefficient increases due to strong horizontal swirl motion. Head loss coefficient was maximum because of strong oscillation of water surface when the range of manhole depth ratios($h_m/D_{in}$) were from 1.0 to 1.5. The average head loss coefficients for CASE A, B, and C were 0.45, 0.37, and 0.30, respectively. Accordingly, U-invert is most effective for energy loss reduction at circular manhole. This head loss coefficients could be available to design the urban sewer system with surcharge flow.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.337-345
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• 1999

The purpose of this study was to compare the shape of root canal after instrumentation with some engine driven NiTi files. Thirty narrow and curved canals(15-35 degree) of mesial canals of extracted human mandibular first molars were divided into three groups. Group 1: After radicular access with Gates Glidden drill, apical shaping using step back method with Flexo file Group 2: After radicular access with Gates Glidden drill, apical shaping with Profile .04 Group 3: Canal shaping with GT file and Profile .04. Using modified Bramante technique, the root was sectioned at 2 mm from apical foramen, height of curvature, 2 mm from canal orifice. Canal centering ratio, amount of transport, amount of dentin removed, shape of canal were measured and statistical analysis is done using SPSS Program V 7.5. The results were as follows: 1. Canal centering ratio of group 3 was the lowest at coronal part, but there was no statistical difference. Centering ratio of group 2 was the lowest at curve part, and there was statistical difference between group 1(P<0.05). Centering ratio of group 2 was the lowest at apical part, but there was no statistic difference. 2. Amount of transport of group 3 was the lowest at coronal part, but there was no statistical difference. Amount of transport of group 2 was the lowest at curve part, and there was statistical difference between group 1(P<0.05). Amount of transport of group 3 was the lowest at apical part, and there was statistical difference between group 1 and group 2, group 1 and group 3(P<0.05). 3. Amount of dentin removed of group 3 was the lowest at coronal part, bur there was no statistical difference. Amount of dentin removed of group 2 was the lowest at curve part, but there was no statistical difference. Amount of dentin removed or group 2 was the lowest at apical part, and there was statistical difference between group 1 and group 2, group 1 and group 3(P<0.05). 4. The shape of the canals after instrumentation varied among the groups. The majority of canals at coronal and curve part for group 1 were round in shape(7 in 10), those at apical part were oval(8 in 10). The majority of canals at coronal part for group 2 were round in shape(7 in 10) and there was no difference in the number of shape at other part. There was no difference in the number of shape at every part for group 3. As above results, NiTi rotary instrumentation showed a trend to remain more centered in the canal than SS file instrumentation. At using NiTi file, coronal shaping with Gates Glidden drill was not statistically different from shaping with GT file. But shaping with GT file showed tapered canals, so it may be said that shaping with GT file is a safe and valuable instrumentation method.