• Journal of Korean Society of Water and Wastewater
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• v.34 no.4
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• pp.259-266
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• 2020

In this study, a pilot-scale (3 ㎥/day) membrane distillation (MD) process was operated to treat digestate produced from anaerobic digestion of livestock wastewater. In order to evaluate the performance and energy cost of MD process, it was compared with the pilot scale (10 ㎥/day) reverse osmosis (RO) process, expected competitive process, under same feed condition. As results, MD process shows stable permeate flux (average 10.1 L/㎡/hr) until 150 hours, whereas permeate flux of RO process was decreased from 5.3 to 1.5 L/㎡/hr within 24 hours. In the case of removal of COD, TN, and TP, MD process shows a high removal rate (98.7, 93.7, and 99% respectively) stably until 150 hours. However, in the case of RO process, removal rate was decreased from 91.6 to 69.5% in COD and from 93.7 to 76.0% in TP during 100 hours of operation. Removal rate of TN in RO process was fluctuated in the range of 34.5-62.9% (average 44.6%) during the operation. As a result of energy cost analysis, MD process using waste heat for heating the feed shows 18% lower cost compare with RO process. Thus, overall efficiency of the MD process is higher then that of the RO process in terms of permeate flux, removal rate of salts, and operating cost (in the case of using waste heat) in treating the anaerobic digestate of livestock wastewater.

• Membrane and Water Treatment
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• v.3 no.2
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• pp.99-111
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• 2012

The performance of ultrafiltration (UF) membranes with molecular weight cut off (MWCO) of 1000 and 3500 Da in clarifying sugar cane juice was investigated, as well as the performance of a nanofiltration (NF) membrane with MWCO of 200 Da and a reverse osmosis (RO) membrane in concentrating sugar cane juice. For both cases the sugar cane juice had been limed and partially clarified. The UF membranes were found to be effective at clarifying the sugar cane juice in terms of purity rise and reduction in turbidity, colour, starch and protein. A purity rise of approximately 6 was achieved by both UF membranes at trans-membrane pressures (TMP) from 15 to 25 bar. However, Brix reduction in the permeate was between 14.5 and 41.85% and 12.11 and 26.52% for 1000 Da and 3500 Da membranes respectively. For the 200 Da and RO membranes the Brix in the concentrate was increased from 7.65 to 12.3 after 3 hours of operation for the 200 Da membrane at a TMP of 10 bar, whilst the Brix in the concentrate was increased from 15.65 to 27.6 after 3 hours of operation for the RO membrane at a TMP of 35 bar. Overall, UF membranes were found to be unsuitable for clarification of sugar cane juice since significant amount of Brix is reduced in the permeate, whilst RO membranes were found to be effective for concentration of sugar cane juice.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.1
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• pp.93-101
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• 2010

Reverse osmosis (RO) membranes have been widely used for desalination as well as water and wastewater treatment facilities. Cleaning process is important to maintain stable operation as well as prevention of membrane fouling. Purpose of this research is to analyze electrostatistic and chemical characteristics after cleaning of RO membrane against $SiO_2$ scale. Four RO membranes of polyamide are used and examined about effect of chemical cleaning. EDTA (ethylene diamine tetraacetic acid) and SDS (sodium dodecil sulfate) and NaOH are applied for cleaning process after operation in synthetic water. Then, cleaning was performed with chemicals such concentration as 6hr, 12hr and 24hr, respectively. As a result, transmittances of FT-IR of four membranes are compared at each cleaning concentration. Ta/Tv shows difference of chemical composition between new membrane and cleaning membrane after cleaning. Type B of RO membrane is turned out to be most vulnerable to cleaning among four membranes. In terms of zeta potential, new membrane has -16 mV to +6 mV on pH while scaled membrane has -18 mV to 2 mV. However, it changed -23mV to 0.9 mV after cleaning. In comparison with existing salt rejection of RO membranes after cleaning, the rejection of the membranes goes down 0.7% maximum. Though cleaning changes the characteristics of membrane surface, it does not greatly affect salt rejection. pH is a critical factor to flux change in PA (polyamide) membrane.

• Clinics in Shoulder and Elbow
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• v.26 no.4
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• pp.416-422
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• 2023

Background: Advancements in airport screening measures in response to 9/11 have resulted in increased false alarm rates for patients with orthopedic and metal implants. With the implementation of millimeter-wave scanning technology, it is important to assess the changes in airport screening experiences of patients who underwent total shoulder arthroplasty (TSA). Methods: Here, 197 patients with prior anatomic and reverse TSA completed between 2013 and 2020 responded to a questionnaire regarding their experiences with airport travel screening after their operation. Of these patients, 86 (44%) stated that they had traveled by plane, while 111 (56%) had not. The questionnaire addressed several measures including the number of domestic and international flights following the operation, number of false alarm screenings by the millimeter-wave scanner, patient body habitus, and presence of additional metal implants. Results: A total of 53 patients (62%) responded "yes" to false screening alarms due to shoulder arthroplasty. The odds of a false screening alarm for patients with other metal implants was 5.87 times that of a false screening alarm for patients with no other metal implants (P<0.1). Of a reported 662 flights, 303 (45.8%) resulted in false screening alarms. Greater body mass index was not significantly lower in patients who experienced false screening alarms (P=0.30). Conclusions: Patients with anatomic and reverse TSA trigger false alarms with millimeter-wave scanners during airport screening at rates consistent with prior reports following 9/11. Patient education on the possibility of false alarms during airport screening is important until improvements in implant identification are made. Level of evidence: IV.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.692-698
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• 2016

Recently, the facility extension construction and maintenance market portion has increased instead of decreased the newly facility construction. In this context, it is important to examine the reverse engineering of MEP (Mechanical Electrical and Plumbing) facilities, which have the high operation and management cost in the architecture domains. The purpose of this study was to suggest the Large Point Cloud-based Pipe Shape Reverse Engineering Method. To conduct the study, the related researches were surveyed and the reverse engineering automation method of the pipe shapes considering large point cloud was proposed. Based on the method, the prototype was developed and the results were validated. The proposed method is suitable for large data processing considering the validation results because the rendering performance standard deviation related to the 3D point cloud massive data searching was 0.004 seconds.

• Journal of Korean Foot and Ankle Society
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• v.14 no.1
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• pp.16-20
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• 2010

Purpose: This study analyzed the clinical and radiographic outcome of the severe hallux valgus corrected with proximal reverse chevron metatarsal osteotomy and Akin osteotomy. Materials and Methods: The study was based on 18 feet (15 patients) of severe hallux valgus (hallux valgus angle ${\geq}40^{\circ}$ or intermetatarsal angle ${\geq}18^{\circ}$) treated with proximal reverse chevron metatarsal osteotomy and followed for more than 1 year. Akin osteotmy was added in 72% of the patients. Clinically preoperative and postoperative AOFAS Hallux Metatarsophalangeal-interphalangeal score, VAS pain score and satisfaction after the surgery were analyzed. Radiologically hallux valgus angle, hallux valgus interphalangeal angle, the intermetatarsal angle and sesamoid position before and after the operation were analyzed. Results: AOFAS Hallux Metatarsophalangeal-interphalangeal score improved from 54.5 (25-78) to 87.7 (70-100) and VAS pain score decreased from 6.0 (3-8) to postoperative 1.2 (0-5). Ninety-six percents of the patients were satisfied with results. Radiologically hallux valgus angle was decreased from $43.3^{\circ}(31-58^{\circ})$ preoperatively to $6.8^{\circ}(-8-27^{\circ})$ postoperatively. The intermetatarsal angle was decreased from $18.4^{\circ}(11-24)^{\circ}$ preoperatively to $5.3^{\circ}(1-12^{\circ})$postoperatively. The sesamoid subluxation was improved from $2.8{\pm}0.4$ preoperatively to $0.4{\pm}0.6$ postoperatively. Conclusion: Proximal reverse chevron metatarsal osteotomy and lateral soft tissue release with additional Akin osteotomy is good treatment option for severe hallux valgus.

• Archives of Plastic Surgery
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• v.36 no.2
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• pp.242-246
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• 2009

Purpose: The majority of nasal bone fractures have been managed by routine procedure of closed reduction and intranasal packing. However, nasal packing can cause nasal injury, hypoxia and patient's discomfort. And, synechiae formation is a frequently occurred after the nasal surgery. Various methods are used to reduce the incidence of synechiae formation. The purpose of this study was to compare routine procedure and nasal packing with reverse "U" shaped silicone sheet with respect to postoperative nasal synechiae formation and final outcome. Methods: We analyzed the medical records of 100 patients with nasal bone fracture who were operated by closed reduction in the last one year. The silicone sheet was designed in reverse "U" fan - shape and inserted between the middle turbinate and the septal wall. Nasal packing was removed at two days after the operation, and silicone sheet was removed at 10 to 14 days. Results: Synechiae in the middle meatus developed in 2 of 75 patients. Although synechiae between the middle meatus and nasal septum occurred in patients, the patients did not complaint of any olfactory disturbance and nasal obstruction. Conclusion: The reverse "U" fan - shape silicone sheet caused less pain for patients and no significant differences in outcome were found. The results of this study suggest that insertion of silicone sheet between the middle meatus and septum can be a useful method in the prevention of intranasal synechiae formation. The reverse "U" silicone sheet is a good alternative for routine packing methods.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.140-147
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• 2004

In reverse engineering, the whole surfaces of the three-dimensional product are measured using 3D positional scanners. The raw triangle meshes constructed from a scanned point set are not well fitted for direct use in the downstream engineering or graphic activities. No object can be fully described by a single scan. Although multiple scans are usually taken and aligned to achieve a complete model, a set of scanned points does not entirely wrap the whole object. This is because some surfaces may be inaccessible to the scanner, so some portion of the scanned surface may be missing. This paper discusses the algorithms of a hole-filling that are crucial to refine the triangle meshes. In this paper, the holes are filled with flat triangles first by subdivision operation and then smoothed with neighboring triangles. This process continues until it converges to a certain user-defined iteration number. Examples are given and discussed to validate the system.

• Environmental Engineering Research
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• v.16 no.4
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• pp.205-212
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• 2011

Reverse osmosis (RO) technology has developed over the past 40 years to control a 44% market share in the world desalting production capacity and an 80% share in the total number of desalination plants installed worldwide. The application of conventional and low-pressure membrane pretreatment processes to seawater RO (SWRO) desalination has undergone accelerated development over the past decade. Reliable pretreatment techniques are required for the successful operation of SWRO processes, since a major issue is membrane fouling associated with particulate matter/colloids, organic/inorganic compounds, and biological growth. While conventional pretreatment processes such as coagulation and granular media filtration have been widely used for SWRO, there has been an increased tendency toward the use of ultrafiltration/microfiltration (UF/MF) instead of conventional treatment techniques. The literature shows that both the conventional and the UF/MF membrane pretreatment processes have different advantages and disadvantages. This review suggests that, depending on the feed water quality conditions, the suitable integration of multiple pretreatment processes may be considered valid since this would utilize the benefits of each separate pretreatment.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.2
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• pp.258-267
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• 2010

The necessity of the new system development arises in both defence and commercial systems industry either when a breakthrough in technology needs to be realized in the form of a brand-new system or when the existing product already in operation needs to be upgraded to satisfy the increasing stakeholder's requirements. In the latter case, it is not rare that specific system technical specifications on the existing products are not available. The purpose of this study is to investigate how to handle the difficulty when an upgraded system is required to be developed based on the existing product whose detailed technical specifications cannot be obtained. A step-by-step process is described based on the reverse engineering of the existing product. As a result, a logical system model is obtained for the product. The process developed is further enhanced and evaluated by the computer-aided system engineering tool. The resulting logical system model should be helpful in the next phase of the new product development.