• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.3
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• pp.69-75
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• 2000

The object of the research is to estimate for pearlite structure of quenched carbon steels. The effects of temperature on physical properties metallic structures and the latent heat by phase transformation were considered. In this study a set of constitutive equations relevant to the analysis of thermo-elasto plastic materials with pearlite phase transformation during quenching process way presented on the basis of continuum thermo-dynamics. The iso-thermal transformation curve of the SM50C was formlated by cubic spline curve. The formulated equations of evolution in pearlite transformation was used for structure analysis. The volume fraction of pearlite was obtained from the results of calculated metallic structure by Finite element equation.

• Journal of Forest and Environmental Science
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• v.30 no.1
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• pp.101-106
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• 2014

The purpose of this research was to figure out the stand structure and growth characteristic with relation to DBH, height, and volume in sixteen Pinus koraiensis plantations of Gangwon province region. Age class was diversely distributed from age class II (16 yr) to age class VIII (77 yr), and, in terms of site index, sixteen regions were superior: nine regions 'high', seven regions 'middle'. The distribution of DBH by sites appeared a bell-shaped curve, and the number of trees was the most in diameter section of 18-22 cm. The dispersion of DBH was various with age and widest ranging from 18 cm to 58 cm in age class VII-VIII. The distribution of height was also a bell-shaped curve with the smaller deviation than the distribution of DBH, and most of trees were in height section of 14-18 m. The correlation of DBH and height was high (r=0.75), and the volume bigger than 1.0 $m^3$ was presented from DBH 35 cm, height 20 m.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.61-70
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• 2004

Generally, ceramics are very difficult-to-cut materials because of its high strength and hardness. The machining process of ceramics can be characterized by cracking and brittle fracture. In the machining of ceramics, edge chipping and crack propagation are the principal reasons to cause surface integrity deterioration. Such phenomenon can cause not only poor dimensional and geometric accuracy, but also possible failure of the ceramic parts. Ceramics can be machined with traditional method such as grinding and polishing. However, such processes are generally cost-expensive and have low material removal rate. Thus, in this paper, to overcome these problems. BN powder, which gives good cutting property, is added for the fabrication of machinable ceramics by volume of 5,10,15,20,25 and 30%. And, mechanical properties, R-curve behavior and machining tests are carried out to evaluate the machining properties of the manufactured machinable ceramics.

• Computers and Concrete
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• v.4 no.6
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• pp.425-436
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• 2007

This study is mainly focused on applying Fuller's ideal gradation curve to theoretically design blended ratio of all solid materials of a reactive powder mortar (RPM), also known as reactive powder concrete (RPC), with the aid of error function, and then to study the effect of fly ash/slag on the performance of RPM. The solid particle is assumed to be spherical particles. Then, the void volume of paste ($V_{\nu}$) and the paste content with specific quality can be obtained. As conclusion, under Fuller's ideal grading curve, the amount of fly ash/slag mixture is higher than that with silica fume along due to it better filled the void within solid particle and obtains higher packing density.

• The KSFM Journal of Fluid Machinery
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• v.18 no.6
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• pp.76-80
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• 2015

The purpose of this study is to understand the cavitation phenomena in centrifugal pumps through computational fluid dynamics method. NPSH characteristic curve is measured from different flow operating conditions. Steady state, liquid-vapor homogeneous method with two equations transport turbulence model is employed to estimate the NPSH curve in centrifugal pumps. The Rayleigh-Plesset cavitation model is adapted as source term for inter-phase mass transfer in order to understand cavitation phenomena in centrifugal pumps. The cavitation incipient curve is clearly estimated at different flows operating conditions. A relationship is made between cavitation incipient and NPSH curve. Also the effects on water vapor volume fraction and pressure load distributions on the impeller blade are also described.

• KCID journal
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• v.17 no.2
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• pp.57-70
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• 2010

This study was performed to analyze the affect of water supply capacity followed by allocating flood control volume in heightening reservoir, of which Baekgog reservoir was selected as a case study in here. Baekgog reservoir is located in Jincheon county, Chungbuk province, of which full water level will be heightened from EL. 100. 1m to EL. 102.1m, and total storage from 21.75M $m^3$ to 26.67M $m^3$. Flood inflow with 200year frequency was estimated to 997 $m^3$/s in peak flow and 22.54M $m^3$ in total volume. Reservoir flood routing was conducted to determine flood limited water levels, which was determined to have scenarios such as EL 97-98-99m in periods of 6.21.-7.20., 7.21.-8.20., and 8.21.-9.20., respectively, EL 97-97-97m, EL 98-98-98m in present reservoir, and EL 99-100-101m, EL 99-99-99m, and EL 100-100-100m in heightened reservoir. Reservoir inflow was simulated by DAWAST model. Annual paddy irrigation requirement was estimated to 33.19M $m^3$ to 2,975ha. Instream flow was allocated to 0.14mm/d from October to April. Operation rule curve was drawn using inflow, irrigation and instream flow requirements data. In case of withdrawal limit reservoir operation using operation rule curve, reduction rates of annual irrigation supply before and after flood control by reservoir were 2.0~4.3% in present size and 1.5~3.6% in heightened size. Reliability on water supply was decreased from 77.3% to 63.6~68.2% in present size and from 81.6% to 72.7~79.5% in heightened size. And reduction rates of water storage at the end of year before and after flood control by reservoir were 7.3~16.5% in present size and 7.7~16.9% in heightened size. But water supplies were done without any water deficiency through withdrawal limit reservoir operation in spite of low flood regulating water level.

• Journal of Veterinary Clinics
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• v.40 no.6
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• pp.438-444
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• 2023

The aim of this study was to analyze the learning curve of a low-volume veterinary surgeon for laparoscopic salpingectomy of Asiatic black bear. A total of 66 Asiatic black bears (Ursus thibetanus) were presented for sterilization using laparoscopic salpingectomy. These 66 bears were divided into three groups of 22 bears according to the order of surgery (A, B, and C groups, 22 bears per group). One veterinarian performed laparoscopic salpingectomy. There was no significant difference in age, body weight, or crown-rump length between groups. The hazard of completion for salpingectomy by 5 minutes was higher (p < 0.0001) in B and C groups than A group, whereas the hazard was not significant different between B and C groups. The factor that affected the hazard of completing salpingectomy by 5 minutes was heart rate, not age or weight. Operation time was 12.61 ± 8.04 minutes for group A, 5.35 ± 4.38 minutes for group B, and 2.80 ± 1.16 minutes for group C. The operation time for salpingectomy shortened over time. However, significant difference in operation time was present only between groups A and C (p = 0.001). The operation time for laparoscopic salpingectomy decreased rapidly for the first 7 bears (p < 0.05). It then decreased gradually until the 66th case. Operation time of laparoscopic salpingectomy was significantly decreased and stabilized after 33 cases (p < 0.05). As a result, the number of bears required for a low-volume veterinary surgeon to be proficient in laparoscopic salpingectomy is 33 or more.

• Journal of International Academy of Physical Therapy Research
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• v.9 no.1
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• pp.1393-1397
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• 2018

The purpose of this study was to examine the effects of combined respiratory physical therapy on respiratory function, spinal curve and spinal mobility for community-dwelling elderlies with restrictive lung diseases. In total, 10 patients participated in an 8-week intervention program of thoracic cage mobilization and breathing exercise in combination. The results of the study are as follows: for respiratory function, the forced expiratory volume in 1 second (FEV1), forced vital capacity(FVC), and FEV1/FVC were significantly improved to $.30{\pm}0.31{\ell}$, $.46{\pm}.42{\ell}$, and $18.10{\pm}11.39%$, respectively (p<.05). For spinal curve, the thoracic curve and the lumbar curve were improved significantly to $-2.20{\pm}1.40^{\circ}$ and $-1.20{\pm}1.14^{\circ}$, respectively (p<.01). For spinal mobility, the thoracic flexion ($3.40{\pm}2.99^{\circ}$), thoracic extension ($3.50{\pm}1.43^{\circ}$), lumbar flexion ($4.50{\pm}4.74^{\circ}$), and lumbar extension($-1.50{\pm}1.84^{\circ}$) were all significantly improved (p<.05). These findings indicate that thoracic cage mobilization and breathing exercise in combination improve the respiratory function, spinal alignment, and spinal mobility in elderly people with restrictive lung diseases.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.2
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• pp.81-91
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• 1998

Water level of irrigation reservoir during the flood season could be kept to a certain level, so called, flood control level by releasing the flood inflow in advance in order to reduce the peak discharge of next coming flood and the damage of inundation. Concept of restriction intensity of water supply was introduced to evaluate the influence of flood control volume on the irrigation water supply. Restriction intensity can be calculated by multiplying the ratio of restriction to the days of restriction which are obtained from the operation rule curve and daily water level of irrigation reservoir and it has the dimension of % day. The method of restriction intensity was applied to the Yedang irrigation reservoir with the observed data of 30 years to review whether the present flood control volume is reasonable or not, and suggest the optimal flood control volume, if possible.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.417-422
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• 2002

The main purpose of this paper is to determine the dynamic optimal shapes of tapered column with constant volume. The linear, parabolic and sinusoidal tapers with the regular polygon cross-section are considered, whose material volume and span length are always held constant. The ordinary differential equation including the effect of axial load is applied to calculate the natural frequencies. The Runge-Kutta method and Regula-Falsi methods are used to integrate the differential equation and compute the frequencies, respectively. Then the dynamic optimal shape whose lowest natural frequency is highest is determined by reading the critical value of the frequency versus section ratio curve plotted by the frequency data. In the numerical examples, the tapered columns are analysed and the numerical result of this study are shown in table and figures.