• Proceedings of the KSME Conference
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• 2001.06a
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• pp.951-955
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• 2001

The experimental comparison between bonded and unbonded types stem-cement interface was carried out on axisymmetric stem-cement-aluminum model of the femoral component of a total hip replacement. Human femur was modeled in non-tapered and tapered($7.5^{\circ}$) aluminum hollow cylinders to emulate the diaphyseal and metaphyseal segments of the femur. For unbonded type, we tested stems with three different taper angles($5^{\circ},\;7.5^{\circ},\;10^{\circ}$). In every case, the cement-aluminum interface was designed to endure 8MPa shear strength. (a measured value at cement-bone interface) We tested aluminum models under axial loading for both cases. As an experimental result, it was found that unbonded stem sustained more axial load as bonded stem in both cases, diaphyseal and metaphyseal models. The unbonded types failed in cement mantle under axial compressive load, while the bonded ones failed in shear at cement-aluminum interface. These results suggest that a polished stem will sustain much higher axial load than a roughened stem. And a polished stem will make more stable cement-bone interface that may promote better osteosythesis around the stem.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.387-392
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• 2000

In cementless total hip replacement(THR), an initial stability of the femoral component is important to long term fixation of femoral stem. The initial stability has close relationship with the relative displacement of prosthesis and spongy bone at the proximal of femur. After implantation of the prosthesis. the surrounding bone is partially shielded from load carrying and starts to resort. Stress shielding is the cause of the loss of proximal bone. Assessing stress distribution of femur is important to predict stress shielding. The initial stability and the stress shielding were investigated for two loading conditions approximating a single leg stance and a stair climbing. Three types of stems were studied by the finite element method to analyze the biomechanical effects of distal filling of cementless femoral stems, Three types of stems employed are a distal filling stem, a distal flexible stem, and a distal tapered stem.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.11
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• pp.2777-2785
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• 2000

In cementless total hip replacement(THR), an initial stability of the femoral component is important to long term fixation of femoral stem. The intial stability has close relationship with the relative displacement of prosthessis and sponge bone at the proximal of femur. After implantation of the proshesis, the surrounding bone is partially shielded from load carrying and starts to resorb. Stress shielding is the cause of the loss of proximal bone. Assessing stress distribution of femur is important to predict stress shielding. The initial stability and the stress shielding were investigated for two loading conditions approximating a single leg stance and a stair climbing. Three types of stems were studied by the finite element method to analyze the biomechanical effects of distal filling of cementless femoral stems. Three types of stems empolyed are a distal filling stem, a distal flexible stem, and a distal tapered stem.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.313-317
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• 2000

In this research, a grafting robot with plug in method is used. Plug in method is a method that uses a tapered axis for scion and a tapered hole for stock as processing style of conjugation parts. In the case of handling a grafting seedling, gripping a stem is doing with simple mechanisms of devising to reduce damages to stems. For example, providing cushions between gripper and stem, and fitting a gripper to a stem. Both scions and stocks need cutting, but there is bigger influence for scions than stocks, so problems of cutting scions and special qualities of grippers are necessary to investigate.

• Hip & pelvis
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• v.35 no.2
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• pp.88-98
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• 2023

Purpose: The objectives of this study were to examine the prevalence and risk factors for development of periprosthetic occult femoral fractures during primary cementless total hip arthroplasty (THA) and to assess the clinical consequences of these fractures. Materials and Methods: A total of 199 hips were examined. Periprosthetic occult femoral fractures were defined as fractures not detected intraoperatively and on postoperative radiographs, but only observed on postoperative computed tomography (CT). Clinical, surgical, and radiographic analysis of variables was performed for identification of risk factors for periprosthetic occult femoral fractures. A comparison of stem subsidence, stem alignment, and thigh pain between the occult fracture group and the non-fracture group was also performed. Results: Periprosthetic occult femoral fractures were detected during the operation in 21 (10.6%) of 199 hips. Of eight hips with periprosthetic occult femoral fractures that were detected around the lesser trochanter, concurrent periprosthetic occult femoral fractures located at different levels were detected in six hips (75.0%). Only the female sex showed significant association with an increased risk of periprosthetic occult femoral fractures (odds ratio for males, 0.38; 95% confidence interval, 0.15-1.01; P=0.04). A significant difference in the incidence of thigh pain was observed between the occult fracture group and the non-fracture group (P<0.05). Conclusion: Occurrence of periprosthetic occult femoral fractures is relatively common during primary THA using tapered wedge stems. We recommend CT referral for female patients who report unexplained early postoperative thigh pain or developed periprosthetic intraoperative femoral fractures around the lesser trochanter during primary THA using tapered wedge stems.

• Research in Plant Disease
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• v.8 no.4
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• pp.224-227
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• 2002

From the necrotic stem of aquaculture Dracaena for living room decoration, we observed conidia on acervuli with occasional setae and perithecia in vivo. Morphological characters were; acervuli, dark brown and 300-500 ${\mu}{\textrm}{m}$ in diameter; conidia, hyaline, aseptate, cylindrical to slightly ellipsoid with rounded apex and narrow truncate base on phialidic conidiophores, 12.5-17.5 ${\mu}{\textrm}{m}$; setae, variable in length 1-4 septate, slightly swollen at the base and tapered to the apex, 200 ${\mu}{\textrm}{m}$; appressoria, dark brown ovate to obovate irregular 5-12.5 ${\mu}{\textrm}{m}$, perithecia on decayed stem, globose, dark brown and black 85-300 ${\mu}{\textrm}{m}$; asci 8 spored, clavate to cylindrical; 50-62.5$\times$8-10 ${\mu}{\textrm}{m}$; ascospores, oval to fusiform, sometimes slightly curved, aseptate, hyaline. Above characteristics were also confirmed in vitro. Colletotrichum state of this fungus was also compared with C. lindemuthianum and C. musae in terms of morphology of conidia and setae and growth on PDA etc. This fungus was identified as Glomerella cingulata(Stonem.) Spaulding & Schrenk(Colletotrichum gloeosporioides(Penz. Sacc.).

• Journal of the Korean Orthopaedic Association
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• v.55 no.6
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• pp.503-510
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• 2020

Purpose: Bipolar hemiarthroplasty is used as an alternative to open reduction and internal fixation for unstable intertrochanteric fractures in elderly patients. Recent advances in medical systems and technologies have resulted in increased survival rates after intertrochanteric fractures of the femur, requiring selection of the appropriate femoral stems considering the mid- to long-term duration of survival. Hemiarthroplasty was performed for unstable intertrochanteric fractures using a double tapered quadrilateral femoral stem (C2 stem), and the clinical and radiological results were evaluated as a five-year follow-up post-surgery. Materials and Methods: From January 2004 to December 2013, 43 patients (43 hips) who underwent hemiarthroplasty with a C2 stem were enrolled in this study. Their mean age was 78.6 years (range, 70-84 years), and the mean follow-up period was 85.4 months (range, 60-96 months). During the follow-up period, clinical parameters, such as the changes in pain, walking ability, and functional status, were examined. Radiologically, changes in the proximal femur, such as osteoporosis and bone resorption of cortical bone, were noted. Complications that occurred during the follow-up period, such as dislocation and prosthetic features, were also reviewed. Results: Initially, the pain was relieved postoperatively, but it increased four years after surgery. The walking ability was reduced by two steps in nine patients after 60 months, and the Harris hip score was reduced significantly postoperatively after two to three years. Radiologically, cortical osteoporosis occurred in 14 patients. Five patients developed cortical bone resorption. Four of them showed nonunion of the trochanteric fracture fragments, and three of them suffered reverse oblique fractures. Conclusion: Careful selection considering the general health condition and remaining lifespan of the patient would be necessary for primary hip hemiarthroplasty using a 3C type cementless femoral stem for unstable intertrochanteric fractures in elderly patients with osteoporosis.

• Journal of the Korean Society of International Agriculture
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• v.30 no.4
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• pp.370-375
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• 2018

In order to promote the mechanized cultivation of perilla for seed, which has been increasing in cultivation area and production recently as demand increases according to the health-functional effects, we carried out this experiment to determine the optimum sowing time of perilla to minimize the seed loss at harvest and increase the yield. We used two different types of perilla varieties, 'Sodam(small-branch)' and 'Deulsaem(multi-branch)', and the sowing time was June 15, June 30, July 15 and August 1. As the sowing time is late, days of growth from sowing to flowering were shortened, and they were shortened from 14, 26 and 31~32 days on June 30, July 15 and August 1 as compared with June 15, respectively. And, the stem length and culm diameter were shortened or tapered and the number of nodes tended to decrease. The number of effective branch was 82%, 61% and 56% on June 30, July 15 and August 1 as compared with June 15, respectively. Accordingly, it seems to make against in securing the yield from July 15. And, the lowest cluster height was generally shorter as the sowing time is late, and the height was below 15cm on July 15 and August 1. It seems that this may work against the machine harvest. There was a high degree of significance between the sowing time and the yield. Although, the total yield was not statistically significant among June 15, June 30 and July 15, the ratio of shattering seed at harvest was in order of July 15, August 1(30.3%)> June 15(15.3%)> June 30(13.5%). Therefore, the net yield except for shattered seed was higher in order of June 30${\geq}$ June 15> July 15> August 1. This tendency was characteristic regardless of variety and sowing method. And, the protein content in perilla seed increased as the sowing time was delayed, and the content was the highest on August 1. The content of crude fat was relatively high on June 15 and July 15 in 'Sodam', and June 30 and July 15 in 'Deulsaem', respectively. And, the content of linolenic acid was found to be the highest on August 1. As a result, the optimal sowing time for machine harvest of perilla for seed is about June 30. At this time, it is determined that the sowing time is the most suitable to be advantageous in increasing the yield of perilla seed, while minimizing the seed loss due to the shattering at harvest.