• Membrane and Water Treatment
• /
• 제8권2호
• /
• pp.137-147
• /
• 2017

A water treatment utility in South Korea operates a large system of pressurized hollow fiber membrane (PHFM) modules. The optimal selection of membrane module for the full scale plant was critical issue and carried out using Risk-based Life Cycle Cost (RbLCC) analysis based on the historical data of operation and maintenance. The RbLCC analysis was used in the process of decision-making for replacing aged modules. The initial purchasing cost and the value at risk during operation were considered together. The failure of modules occurs stochastically depending on the physical deterioration with usage over time. The life span of module was used as a factor for the failure of Poisson's probability model, which was used to obtain the probability of failure during the operation. The RbLCC was calculated by combining the initial cost and the value at risk without its warranty term. Additionally, the properties of membrane were considered to select the optimum product. Results showed that the module's life span in the system was ten years (120 month) with safety factor. The optimum product was selected from six candidates membrane for a full scale water treatment facility. This method could be used to make the optimum and rational decision for the operation of membrane water purification facility.

• Nuclear Engineering and Technology
• /
• 제53권11호
• /
• pp.3528-3542
• /
• 2021

A detailed geometrical model of a Krško reactor core was developed using a Monte Carlo neutron transport code MCNP. The main goal of developing an MCNP core model is for it to be used in future research focused on ex-core calculations. A script called McCord was developed to generate MCNP input for an arbitrary fuel cycle configuration from the diffusion based core design package CORD-2, taking advantage of already available material and temperature data obtained in the nuclear core design process. The core model was used to calculate 3D power density profile inside the core. The applicability of the calculated power density distributions was tested by comparison to the CORD-2 calculations, which is regularly used for the nuclear core design calculation verification of the Krško core. For the hot zero power and hot full power states differences between MCNP and CORD-2 in the radial power density profile were <3%. When studying axial power density profiles the differences in axial offset were less than 2.3% for hot full power condition. To further confirm the applicability of the developed model, the measurements with in-core neutron detectors were compared to the calculations, where differences of 5% were observed.

• The Journal of Asian Finance, Economics and Business
• /
• 제8권7호
• /
• pp.365-373
• /
• 2021

This paper investigates the presence of momentum profits in the Saudi stock market. The study applied a quantitative method by utilizing monthly closing prices of 194 listed firms on Tadawal (Saudi Stock Market). The data from January 2010 to February 2019 is taken from the Tadawal market database for analysis. The sample is further divided into two equal sub-samples based on the structural changes that occurred in the Saudi stock market. Moreover, the high- and low-value traded portfolios are also constructed to examine the presence of momentum profits. Sixteen investment strategies are formed for each sample. The results show a very strong presence of momentum profits in the Saudi stock market for the full sample as well as for the sub-samples. The momentum profits are observed for a longer investment horizon. The results confirm that the short or medium-term formation of portfolios produces negative momentum returns for high-value traded stocks. The low-value traded stocks portfolios give similar results to the full sample results in terms of momentum profits. The results suggest that an investor should keep an eye on the past performance of desired stocks for at least three-nine months in which they are willing to invest.

• 대한두개안면성형외과학회지
• /
• 제22권6호
• /
• pp.337-340
• /
• 2021

Full-thickness nasal tip reconstruction is a challenging process that requires provision of ample skin and soft tissue, and intricate cartilage structure that maintains its architecture in the long term. In this report, we describe reconstruction of a full-thickness nasal tip and ala defect using a posterior auricular artery perforator based chondrocutaneous free flap. The flap consisted of two lay ers of skin covering conchal cartilage, and was based on a perforating branch of the posterior auricular artery. A superficial vein was secured at the posterior margin. The donor perforator was anastomosed to a perforating branch of the lateral nasal artery. The superficial vein was connected to a superficial vein of the surrounding soft tissue. The donor healed well after primary closure. The flap survived without complications, and the contour of the nasal rim was sustained at follow-up 6 months later. As opposed to combined composite reconstructions using a free cartilage graft together with a small free flap or pedicled nasolabial flap, the posterior auricular artery perforator free flap encompasses all required tissue types, and is similar in contour to the alar area. This flap is a useful option in single-stage reconstruction of nasal composite defects.

• Structural Monitoring and Maintenance
• /
• 제9권4호
• /
• pp.359-371
• /
• 2022

Bridges are critical to the civil engineering infrastructure network as they facilitate movement of people, the transportation of goods and services. Given the aging of bridge infrastructure, federal officials mandate visual inspections biennially to identify necessary repair actions which are time, cost, and labor-intensive. Additionally, the expansion joints of bridges are rarely monitored due to cost. However, expansion joints are critical as they absorb movement from thermal effects, loadings strains, impact, abutment settlement, and vehicle motion movement. Thus, the need to monitor bridge expansion joints efficiently, at a low cost, and wirelessly is desired. This paper addresses bridge joint monitoring needs to develop a cost-effective, real-time wireless system that can be validated in a full-scale bridge structure. To this end, a wireless expansion joint monitoring was developed using commercial-off-the-shelf (COTS) sensors. An in-service bridge was selected as a testbed to validate the performance of the developed system compared with traditional displacement sensor, LVDT, temperature and humidity sensors. The short-term monitoring campaign with the wireless sensor system with the internet protocol version 6 over the time slotted channel hopping mode of IEEE 802.15.4e (6TiSCH) network showed reliable results, providing high potential of the developed system for effective joint monitoring at a low cost.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2023년도 봄 학술논문 발표대회
• /
• pp.175-176
• /
• 2023

The masonry structure is constructed by cement mortar binding material of brick objects and uses reinforced hardware(connected hardware or wall tie) together when building. However, over time, the corrosion of reinforced steel and the deterioration of joint mortar as well as bricks cause the risk of collapse. In particular, when the externally decorated brick wall is installed on the concrete girder for each floor, the angle bracket is not constructed or corroded, the full-layer weight load is applied to the wall of 0.5B, which is an example of full-scale or collapse. As a result of the evaluation, it was confirmed that the performance was improved compared to the existing bracket, and we plan to carry out a real-life test and long-term performance review of the building using the bracket in the future.

• 대한치과보철학회지
• /
• 제38권3호
• /
• pp.360-365
• /
• 2000

The completely edentulous patient has few treatment options in conventional dentistry. When implants are considered, treatment plans range from a 2-implant overdenture to a completely implant-supported prosthesis. Fixed prosthesis is often the preferred selection of the edentulous patient. fixed full-arch cert amo-metal restorations can be a predictable implant treatment modality for the edentulous patient. Implant-supported fixed prosthesis has several advantages: predictability, fixedness, retrievability, improved function, lower maintenance of prosthesis, long-term published success. Edentulous patients with a severely resorbed mandible often experience problems with their dentures. Treatment concepts involving two to four implants for the support of an overdenture have been proposed. There seems to be no need to insert more than two endosteal implants to support an overdenture, however, long-term prospective studies are needed to support this notion. Using short endosseous implants and an overdenture in the extremely resorbed mandible is a justified treatment option because of the relative simplicity and low morbidity of this treatment strategy. Implant-supported overdenture has several advantages: Cost, retrievability, hygiene access, profile and contour control, increased retention and stability, implant installed in a predicted region(ant. mandible).

• International Journal of Concrete Structures and Materials
• /
• 제10권4호
• /
• pp.407-424
• /
• 2016

This study tests ten full-size simple-supported beam specimens with the high-strength reinforcing steel bars (SD685 and SD785) using the four-point loading. The measured compressive strength of the concrete is in the range of 70-100 MPa. The main variable considered in the study is the shear-span to depth ratio. Based on the experimental data that include maximum shear crack width, residual shear crack width, angle of the main crack and shear drift ratio, a simplified equation are proposed to predict the shear deformation of the high-strength reinforced concrete (HSRC) beam member. Besides the post-earthquake damage assessment, these results can also be used to build the performance-based design for HSRC structures. And using the allowable shear stress at the peak maximum shear crack width of 0.4 and 1.0 mm to suggest the design formulas that can ensure service-ability (long-term loading) and reparability (short-term loading) for shear-critical HSRC beam members.

• 한국경영과학회지
• /
• 제23권2호
• /
• pp.187-200
• /
• 1998

This paper presents an original approach for solving short-term power scheduling in extended power system with two fuels in a unit and a limited fuel using Lagrangian relaxations. The underlying model incorporates the full set of costs and constraints including setup, production, ramping, and operational status, and takes the form of a mixed integer nonlinear control problem. Moreover, the mathematical model developed includes two fuels in a unit and a limited fuel, regulation reserve requirements of prespecified group of units. Lagrangian relaxation is used to disaggregate the model by generator into separate subproblems which are then solved with a nested dynamic program including empirical knowledges. The strength of the methodology lies partially in its ability to construct good feasible solutions from information provided by the dual. Thus, the need for branch-and-bound is eliminated. In addition, the inclusion of two fuels in a unit and a limited fuel provides new insight into the limitations of current techniques. Computational experience with the proposed algorithm indicates that Problems containing up to 23 units including 8 unit used two fuels and 24 time periods can be readily solved in reasonable times. Duality gaps of less than 4％ were achieved.

• Advances in pediatric surgery
• /
• 제19권2호
• /
• pp.130-139
• /
• 2013

The application of laparoscopic techniques for the surgical management of Hirschsprung's disease is the recent trend. We described the surgical technique and postoperative long-term outcomes of the one-stage, laparoscopic-assiseted endorectal pull-through operation for Hirschsprung's disease. The technique uses three to four small abdominal ports. Laparoscopic mobilization of the sigmoid colon and rectum is performed and marginal artery-preserving colon pedicle is prepared. The rectal mobilization is performed using a transanal endorectal sleeve technique. The anastomosis is performed 0.5~1 cm above the dentate line. The age at surgery ranged from 6 days to 4 years. The average operative time was 144 minutes. Almost all of the patients passed stool and flatus within 36 hours of surgery. The average hospital stay after surgery was 6.5 days. Among 42 patients, 32 patients older than 3 years old were evaluated for function on defecation. All 32 patients have been continent, of those who needed laxatives were 11 (34.3%) due to constipation and overflow incontinence. Four children (12.5%) have remained dependent on laxatives. Laparoscopic-assisted endorectal pull-through operation for Hirschsprung's disease appears to be safe, provides the less pain, shorter time to full feeding, shorter hospital stay, and excellent cosmetic outcomes. Helping patients and parents ensure the quality of life, they should be provided with counseling, education, and longer-term follow-up care.