• Membrane and Water Treatment
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• v.3 no.3
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• pp.169-179
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• 2012

One of the major limitations in the use of commercial aromatic polyamide thin film composite (TFC) reverse osmosis (RO) membranes is to maintain high performance over a long period of operation, due to the sensitivity of polyamide (PA) skin layer to oxidizing agents, such as chlorine, even at very low concentrations in feed water. This article reports surface modification of a commercial TFC RO membrane (BW30-Dow Filmtec) by covering it with a thin film of poly(vinyl alcohol) (PVA) crosslinked with glutaraldehyde (GA) to improve its resistance to chlorine. Crosslinking reaction was carried out at 25 and $40^{\circ}C$ by using PVA 1.0 wt.% solutions at different GA/PVA mass ratio, namely 0.0022, 0.0043 and 0.013. Water swelling measurements indicated a maximum crosslinking density for PVA films prepared at $40^{\circ}C$ and GA/PVA 0.0043. ATR-FTIR and TGA analysis confirmed the reaction between GA and PVA. SEM images of the original and modified membranes were used to evaluate the surface coating. Chlorine resistance of original and modified membranes was evaluated by exposing it to an oxidant solution (NaClO 300 mg/L, NaCl 2,000 mg/L, pH 9.5) and measuring water permeability and salt rejection during more than 100 h period. The surface modification effectively was demonstrated by increasing the chlorine resistance of PA commercial membrane from 1,000 ppm.h to more than 15.000 ppm.h.

• Journal of Korean Foot and Ankle Society
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• v.14 no.1
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• pp.25-30
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• 2010

Purpose: The purpose of this study was to evaluate the clinical and radiological outcomes of the S.E.R.I. (simple, effective, rapid, inexpensive) operation for the bunionette deformity. Materials and Methods: Between March 2005 and February 2009, 22 patients (26 feet) who had been treated for the bunionette deformity with minimally invasive osteotomy were reviewed retrospectively. Clinically, Visual Analogue Scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) score, shoes selectivity, disappearance of callus and patient's satisfaction level by Coughlin scoring system were evaluated. Radiologically, the bunionette was classified as four types according to the Fallat classification. The 4-5$^{th}$ intermetatarsal angle (4-5$^{th}$ IMA), the 5$^{th}$ metatarsophalangeal angle (5$^{th}$ MPA) and the length of 5th metatarsal bone (5$^{th}$ MTL) were analyzed at preoperatively and at final follow up visit. Results: VAS improved from $6.8{\pm}1.8$ points to $2.2{\pm}1.8$ points (p<0.05). AOFAS score improved from $54.0{\pm}14.2$ points to $90.0{\pm}4.8$ points (p<0.05). There was no change in shoes selectivity. 9 feet (34.6%) were satisfied with excellent results, 16 feet (61.5%) with good results and 1 foot (3.9%) with fair results. The average 4-5$^{th}$ IMA was corrected from $10.1{\pm}2.3^{\circ}$ to $4.4{\pm}1.7^{\circ}$ (p<0.05). The average 5$^{th}$ MPA was corrected from $11.5{\pm}8.6^{\circ}$ to $-0.1{\pm}4.1^{\circ}$ (p<0.05). The average 5$^{th}$ MTL was changed from $66.1{\pm}4.3$ millimeters to $64.1{\pm}4.4$ millimeters (p=0.069). There was no malunion, nonunion or delayed union and other perioperative complications. Conclusion: S.E.R.I. operation is less invasive and easy technique. This procedure is recommendable for the treatment of the bunionette deformity.

• Journal of Korean Foot and Ankle Society
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• v.24 no.4
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• pp.135-141
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• 2020

Purpose: This study evaluated the results of two groups-the early group and midterm group-comparatively in the treatment of hallux valgus using a scarf osteotomy. Materials and Methods: From January 2005 to December 2009 (Group 1) and from January 2010 to December 2013 (Group 2), this study compared hallux valgus cases treated by a scarf osteotomy by a single surgeon with at least a five-year follow-up. Results: The average ages of Group 1 and Group 2 were 50.5 and 51.7 years old, respectively. The average follow-up of Groups 1 and 2 were 7.4 and 6.2 years, respectively. Groups 1 and 2 had 86 cases (53 patients) and 93 cases (64 patients) with at least a five-year follow-up, respectively. The average hallux valgus angle (HVA) and 1-2 intermetatarsal angle (IMA) of Group 1 were improved from 31.3° and 13.9° preoperatively to 11.3° and 6.8° at the final follow-up, respectively (p<0.001). The average HVA and 1-2 IMA of Group 2 were improved from 31.7° and 13.4° preoperatively to 8.9° and 6.6° at the final follow-up, respectively (p<0.001). The mean American Orthopaedic Foot and Ankle Society (AOFAS) score of both groups increased from 48.5 and 45.0 points preoperatively to 73.7 and 82.4 points at the final follow-up, respectively. The numbers of patient-assessed subjective satisfaction of Groups 1 and 2 at the final follow-ups were as follows: excellent, 27 and 36 (31.4%, 38.7%); good, 34 and 49 (39.5%, 52.7%); fair, 13 and 5 (15.1%, 5.4%); poor, 12 and 3 (13.9%, 3.2%); respectively. Neither troughing nor stress fractures occurred in both groups. Conclusion: Scarf osteotomy for treating hallux valgus is an excellent surgical method with a relatively low incidence of complications. The results in Group 2 were better than those in Group 1, showing that more surgical experience and evolution of the techniques provided better results.

• Journal of Korean Society for Quality Management
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• v.32 no.1
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• pp.144-154
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• 2004

The bounded adjustment is known to be more efficient than repeated adjustment when the cost is incurred for engineering process control. The procedure of the bounded adjustment is to adjust the process when the one-step predicted deviation exceeds the adjustment limit by the amount of the prediction. In this paper, two run rules are proposed and studied In order to improve the efficiency of the traditional bounded adjustment procedure. The efficiency is studied in terms of the standardized cost through Monte Carlo simulation when the procedure is operated with and without the run rules. The adjustment procedure operated with run rules turns out to be more robust for changes in the process and cost parameters.

• Journal of Korean Foot and Ankle Society
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• v.27 no.4
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• pp.123-130
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• 2023

Purpose: "Hallux valgus" is a common disease encountered in clinical practice and is accompanied by foot deformities. Conservative treatment is commonly used in the early stages of hallux valgus. On the other hand, surgical treatment often becomes necessary as the deformity progresses. Surgical treatments involve various osteotomy methods or joint fusion procedures combined with soft tissue release, and outcomes from these surgical treatments are generally favorable. This study compared two soft tissue release techniques in the hallux region. Materials and Methods: This study conducted a retrospective cohort study on 48 participants who underwent surgical treatment for hallux valgus at a single institution from March 1, 2018, to March 31, 2023. A scarf osteotomy was performed in all cases, and the "Modified Mcbride procedure" or "Trans-articular approach" was done for soft tissue release. Hallux valgus angle (HVA), intermetatarsal angle (IMA), and the degree of subluxation of the lateral sesamoid were measured through simple foot radiographs taken before surgery and one year after surgery. Results: In the Modified Mcbride procedure group, HVA, IMA, and the sesamoid position grade decreased from 34.94° to 9.98°, 15.64° to 5.44°, and 2.47 to 0.44, respectively. In the trans-articular approach group, HVA, IMA, and the sesamoid position grade decreased from 33.42° to 7.34°, 15.06° to 6.03°, and 2.17 to 0.58, respectively. There was no significant difference in these changes between the preoperative and one-year postoperative measurements for both techniques (p-value>0.05). Conclusion: A radiological assessment of soft tissue release through the Modified Mcbride procedure and trans-articular approach in hallux valgus did not show significant differences. Therefore, both surgical techniques can be considered in the distal soft tissue release for a hallux valgus correction.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.723-729
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• 2005

Traditional statistical process control(SPC) applied to discrete part industry in the form of control charts can look for and eliminate assignable causes by process monitoring. On the other hand, engineering process control(EPC) applied to the process industry in the form of feedback control can maintain the process output on the target by continual adjustment of input variable. This study presents controlling and monitoring rules adopted variable sampling interval(VSI) to change sampling intervals in a predetermined fashion on the predicted process levels for integrated EPC and SPC systems. Twelve rules classified by EPC schemes(MMSE, constrained PI, bounded or deadband adjustment policy) and type of sampling interval combined with EWMA chart of SPC are proposed under IMA(1,1) disturbance model and zero-order (responsive) dynamic system. The properties of twelve control rules under three patterns of process change(sudden shift, drift and random shift) are evaluated and discussed through simulation and control rules for integrated VSI EPC and SPC systems are recommended.

• Communications for Statistical Applications and Methods
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• v.7 no.2
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• pp.435-446
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• 2000

Statistical process control(SPC) and engineering process control(EPC) are two strategies for quality improvement that have been developed independently. EPC seeks to minimize variability by adjusting compensatory variables in order to make the process level close to the target, while SPC seeks to reduce variability by monitoring and eliminating causes of variation. One purpose of this paper is to propose the IMA(0,1,1) model as the in-control process model. For the out-of-control process model we consider two cases; one is the case with a step shift in the level, and the other is the case with a change in the nonstationarity. Another purpose is to suggest the use of an integrated process control procedure with adjustment and monitoring, which can consider the proposed process model effectively. An integrated control procedure will improve the process control activity significantly for cases of the proposed model, when compared to the procedure of using either EPC or SPC, since EPC will keep the process close to the target and SPC will eliminate special causes.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.1
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• pp.39-45
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• 2007

In this paper, we developed an intelligent web based e-learning system based on multi agents. To do development of the system, we applied an inclination test that is based on the education theory to do grouping the desirable e-learning community. The proposed system, Intelligent Web based e-learning Multi Agent System (IMAS), is used the multi agents paradigm including learning manner by neural network for grouping of e-learning community and a new distributed multi agent framework proposed here.

• Natural Product Sciences
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• v.1 no.1
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• pp.17-24
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• 1995

The effects of orchildectomy with/without testosterone replacement in wale rats, and ovarectomy with estrogen replacement in female rats on lipid peroxidation were studied in male and female rats fed with diets fortified with 20% w/w, soybean oil or palm oil for 4 months. Serum, liver and heart homogenates were assayed for malonaldehyde and conjugated diene levels. Orchidectomy was found to reduce levels of lipid peroxidation products in the serum, liver and heart. Testosterone replacement did not increase the lipid peroxidation products to levels in the non-orchildectomised rats, while estrogen did not influence lipid peroxidation significantly. Palm oil decreased, but soybean oil increased lipid peroxidation in the liver and heart of both the castrated and sex hormone-replaced male and female rats.

• Journal of Korean Foot and Ankle Society
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• v.11 no.2
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• pp.166-170
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• 2007

Purpose: To evaluate the clinical and radiologic results of the Ludloff osteotomy for moderate to severe hallux valgus deformity retrospectively. Materials and Methods: Between January 2003 and October 2006, 33 patients (42 feet) who had undergone with Ludloff osteotomy combined with distal soft tissue procedure were followed up for more than one year. The average follow-up period was 14.6 months and the average age at the time of surgery was 47.7 years (26-70 years). The American Othopeaedic Foot and Ankle Society (AOFAS) score was used for clinical outcome assessments. We analyzed the hallux valgus angle (HVA), the first-second intermetatarsal angle (IMA) and the degrees of the tibial sesamoid subluxation in preoperative and the last follow-up radiographs. Results: The AOFAS score improved from a preoperative average of 45.6 points to an average 84.3 points at the last follow-up. HVA and IMA were 34.8 and 14.5 degrees preoperatively, 17.2 and 5.9 degrees at the last follow-up. The tibial sesamoid position improved from a preoperative average of grade 2.5 to the last follow-up average of grade 1.2. Conclusion: Ludloff osteotomy produced satisfactory results for moderate to severe hallux valgus deformity.