• Journal of Korea Water Resources Association
• /
• v.39 no.5 s.166
• /
• pp.405-415
• /
• 2006

The deposition of sewer solids during dry weather in combined sewer systems results in a loss of flow capacity that may restrict flow and cause a local flooding and enhanced solids deposition. Sewer solid accumulations in drainage systems also create the 'first-flush' phenomena during wet weather runoff periods. In order to solve these problems, measurement of these loadings for a given sewer system for extended period is needed but this task is very difficult and extremely expensive. In this study, generalized procedures for estimating sewer sediment solid during dry weather in combined sewer systems developed by the U. S. Environmental Protection Agency were applied in a drainage system in Korea. As result, the appropriate equation can be selected and applied according to the available data. However, the estimated solid sediment shows considerable difference between methods which classified by model and estimation methods of variable. The estimated values using equations (1) $\sim$ (4) are greater than that of equations (5) $\sim$ (9) and intermediate models show greater values than elaborate or simplest models. The comparison between simulated and measured solid deposition is difficult due to the absent of measurement data, but this estimation method can be used usefully for the management of sewer solid with reduction of cost and effort if the measurement is carried out and the equation is adjusted according to the actual drainage systems in Korea.

• Advances in nano research
• /
• v.9 no.1
• /
• pp.1-13
• /
• 2020

In this work, the electrical potential (EP) technique with an artificial neural networks (ANNs) for monitoring of nanostructures are used for the first time. This study employs an expert system to identify size and localize hidden nano-delamination (N.Del) inside layers of nano-pipe (N.P) manufactured from Basalt Fiber Reinforced Polymer (BFRP) laminate composite by using low-cost monitoring method of electrical potential (EP) technique with an artificial neural networks (ANNs), which are combined to decrease detection effort to discern N.Del location/size inside the N.P layers, with high accuracy, simple and low-cost. The dielectric properties of the N.P material are measured before and after N.Del introduced using arrays of electrical contacts and the variation in capacitance values, capacitance change and node potential distribution are analyzed. Using these changes in electrical potential due to N.Del, a finite element (FE) simulation model for N.Del location/size detection is generated by ANSYS and MATLAB, which are combined to simulate sensor characteristic, therefore, FE analyses are employed to make sets of data for the learning of the ANNs. The method is applied for the N.Del monitoring, to minimize the number of FE analysis in order to keep the cost and save the time of the assessment to a minimum. The FE results are in excellent agreement with an ANN and the experimental results available in the literature, thus validating the accuracy and reliability of the proposed technique.

• Journal of the Korean Arthroscopy Society
• /
• v.2 no.1
• /
• pp.25-32
• /
• 1998

The distinction between isolated and combined injuries is crucial both for treatment and prognosis. For most combined injuries, surgical treatment continues to be favored over nonoperative treatment. It is generally agreed that isolatel PCL injuries do well without surgery. There has been an interest by many authors to fix the graft directly to the posterior aspect of the tibia(tibial inlay). With this procedure, tibial graft fixation will be more direct and theoretically reduce the bending effects of the graft with a fixation site far away from the tibial insertion. Modified tibial inlay technique, which is the posterior approach does not require the patient to be in the prone or lateral decubitus position during the operation. Use of a double-bundle reconstructive technique is attractive and has been performed by some surgeons. At this time, this procedure is still being investigated and should not be routinely used in the clinical setting until studies have indicated an advantage over current single-bundle techniques. However theologically, double-bundle reconstructive technique is more useful in severe posterior unstable knee. Recent advances have increased our knowledge of the anatomy and mechanical characteristics of the PCL. Basic science research has further increased our awareness of the interaction of the posterolateral structures with the PCL. To achieve restoration of normal posterior laxity, it is critical to address the posterior as well as the postero-lateral structures. Surgical treatment is often complex and requires a wide range of surgical techniques and skills to treat associated injuries. When the PCL is reconstructed, most surgeons choose to reconstruct the anterolateral component using a graft of sufficient size and strength. The initial postoperative rehabilitation should be addressed cautiously in an effort to avoid excessive forces on delicate repairs and reconstructions in these complex injuries. Further research is necessary to evaluate new surgical approaches such as double-bundle reconstructions and tibial inlay techniques as well as improved techniques for capsular and collateral ligament injuries.

• Journal of Korea Water Resources Association
• /
• v.39 no.7 s.168
• /
• pp.575-581
• /
• 2006

This paper presents a systematic approach for the economical design of stormwater quality control systems. For the design of runoff quality control system (RQCS), the rainfall-runoff process requires the local rainfall data recorded continuously. In this study the rainfall probability distribution is assumed to follow an exponential decay function. Applying the exponential decay function, the normalized curves are derived to explain the non-exceedance probability distributions. The optimal curves for the determination of the RQCS size are derived based on the overflow risk. Comparison of the optimal capture volume and peak runoff rate to those computed by an urban rainfall-runoff model(ILLUDAS) demonstrates that the optimal CSOs(Combined Sewer Overflows) curves derived in this study can be utilized for the design of stormwater quality control systems in Korea avoiding an excessive computational effort based on over flow risks.

• Advances in aircraft and spacecraft science
• /
• v.5 no.4
• /
• pp.431-444
• /
• 2018

Numerical simulations have been conducted to study the unstart/restart characteristics of an over-under turbine-based combined-cycle propulsion system (TBCC) inlet during the inlet transition phase. A dual-solution area exists according to the Kantrowitz theory, in which the inlet states may be different even with the same input parameters. The entire transition process was divided into five stages and the unstart/restart hysteresis loop for each stage was also obtained. These loops construct a hysteresis surface which separates the operating space of the engine into three parts: in which a) inlet can maintain a started state; b) inlet keeps an unstarted state; c) inlet state depends on its initial state. During the transition, the operation of the engine follows a certain order with different backpressures and splitter angles, namely control route, which may result in disparate inlet states. Nine control routes with different backpressures and transition stages were designed to illuminate the route-dependent behavior of the inlet. The control routes operating towards the unstart boundary can make the inlet transit from a started state into an unstarted one. But operating backward the same route cannot make the inlet restart, additional effort should be made.

• Food Science and Biotechnology
• /
• v.16 no.3
• /
• pp.337-342
• /
• 2007

Conventional methods for pathogen detection and identification are labor-intensive and take days to complete. Biosensors have shown great potential for the rapid detection of foodborne pathogens. Fiber-optic biosensors have been used to rapidly detect pathogens because they can be very sensitive and are simple to operate. However, many fiber-optic biosensors rely on manual sensor handling and the sandwich assay, which require more effort and are less sensitive. To increase the simplicity of operation and detection sensitivity, a binding inhibition assay method for detecting Listeria monocytogenes in food samples was developed using an automated, fiber-optic-based immunosensor: RAPTOR (Research International, Monroe, WA, USA). For the assay, fiber-optic biosensors were developed by the immobilization of Listeria antibodies on polystyrene fiber waveguides through a biotin-avidin reaction. Developed fiber-optic biosensors were incorporated into the RAPTOR to evaluate the detection of L. monocytogenes in frankfurter samples. The binding inhibition method combined with RAPTOR was sensitive enough to detect L. monocytogenes ($5.4{\times}10^7\;CFU/mL$) in a frankfurter sample.

• Journal of computational fluids engineering
• /
• v.16 no.1
• /
• pp.30-35
• /
• 2011

In this paper, our effort to apply 3-D Virtual Reality system for stereoscopic visualization of mesh data on the web is briefly described. This study is an extension of our previous and on-going research efforts to develop an automatic grid generation program specialized for wing mesh, named as eGWing. The program is developed by using JAVA programming language, and it can be used either as an application program on a local computer or as an applet in the network environment. In this research advancing layer method(ALM) augmented by elliptic smoothing method is used for the structured grid generation. And to achieve a stereoscopic viewing capability, two graphic windows are used to render its own viewing image for the left and right eye respectively. These two windows are merged into one image using 3D monitor and the viewers can see the mesh data visualization results with stereoscopic depth effects by using polarizing glasses. In this paper three dimensional mesh data visualization with stereoscopic technique combined with 3D monitor is demonstrated, and the current achievement would be a good start-up for further development of low-cost high-quality stereoscopic mesh data visualization system which can be shared by many users through the web.

• Development and Reproduction
• /
• v.14 no.1
• /
• pp.27-34
• /
• 2010

A fertilized oocyte can get the competence for implantation through cleavage and stage-specific gene expression. These are under the control of autonomous and exogenous regulators including physiological culture condition. Endogenous and exogenous growth factors are considered as critical regulators of cleaving embryos during travel the oviduct and uterus. In this study, an effort was made to evaluate comprehensively the quality of embryos for implantation, grown in media enriched with EGF and PAF. The study evaluated developmental rates on given time, blastulation and hatching rates, and adhesion rates. Developmental rates of blastocyst to the hatching stage were significantly high in PAF treated group compared to the control in a dose-dependent manner but not in EGF group. Implantation rates were significantly high both PAF and EGF in a dose-dependent manner. H7, a PKC inhibitor, blocked the process of hatching of the blastocysts but combined treatment of EGF and PAF enhanced the hatching and implantation of blastocsyts. Based on these results it is suggested that EGF and PAF support acquirement of implantation competence at blastocyst stage through a PKC pathway.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.15 no.2
• /
• pp.65-73
• /
• 2007

The use of an Exhaust Gas Recirculation(EGR) for a diesel engine with variable geometry turbocharger(VGT) has confronted how to obtain the amount of EGR for NOx reduction requirement at wide operating range and less side effect. Through a combined effort of modeling(wave action simulation) and experiment, an investigation into the effect of EGR area ratio and pipe length on EGR characteristics of common rail diesel engine with VGT has been performed. For accurate computation, calibration of constants involved in empirical and semi-empirical correlations has been performed at a specific operating point, before of its use for engine simulation. From the results of this study, it was found that EGR rate is sharply increased with increasing EGR area ratio until area ratio of 0.3. However, the effect of EGR area ratio on EGR rate is negligible beyond this criteria. This study also investigates the effect of EGR pipe length on a EGR amount and pulsating flow characteristics at EGR junction. The results showed that the longer EGR pipe length, the lower EGR amount was achieved due to the flow loss resulting in lower amplitude of pressure wave.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.8 no.2
• /
• pp.240-253
• /
• 1996

The refrigeration cycle of automobile air-conditioners is simulated in an effort to provide a computational tool for optimum thermodynamic design. In the simulation, thermodynamic and heat transfer analysis was performed for the four major components : evaporator, condenser, compressor, and expansion valve. Effectiveness-NTU method was used for modeling both evaporator and condenser. The evaporator was divied into many subgrids and simultaneous cooling and dehumidifying analysis was performed for each grid to predict the performance accurately. Blance equations were used to model the compressor instead of using the compressor map. The performance of each component was checked against the measured data with CFC-12. Then, all the components were combined to yield the total system performance. Predicted cycle points were compared against the measured data with HFC-134a and the deviation was found to be less than 5% for all data. Finally, the system model was used to predict the performance of CFC-12 and HFC-134a for comparison. The results were very reasonable as compared to the trend deduced from the measured data.