• Journal of Hydrogen and New Energy
• /
• v.21 no.5
• /
• pp.355-363
• /
• 2010

High purity hydrogen, 97-99 vol.%, with CO at just ppm levels was obtained in a fixed bed of iron oxide employing the steam-iron cycle operation with reduction at 823K and oxidation in a steam-$N_2$ mixture at 773K TGA experiments indicated that temperature of the reduction step as well as its duration are important for preventing carbon build-up in iron and the intrusion of $CO_2$ into the hydrogen product. At a reduction temperature of 823K, oxide reduction by $H_2$ was considerably faster than reduction by CO. If the length of the reduction step exceeds optimal value, low levels of methane gas appeared in the off-gas. Furthermore, with longer durations of the reduction step and CO levels in the reducing gas greater than 10 vol.%, carbidization of the iron and/or carbon deposition in the bed exhibited the increasing pressure drop over the bed, eventually rendering the reactor inoperable. Reduction using a reducing gas containing 10 vol.% CO and a optimal reduction duration gave constant $H_2$ flow rates and off-gas composition over 10 redox reaction cycles.

• Journal of Environmental Impact Assessment
• /
• v.20 no.1
• /
• pp.71-78
• /
• 2011

This paper aims to assessing impact of reduction of non-point source pollution in the Bokha Stream watershed. The BASINS/HSPF model was calibrated and verified for water flow and water qualities using Total Maximum Daily Load 8days data from 2006 to 2007. Accuracy of the BASINS/HSPF models in simulating hydrology and water quality was compared and there were somewhat differences of statistical results, but water flow and water quality were simulated in good conditions over the study period. The applicability of models was tested to evaluate non-point source control scenarios to response hydrology and water quality in the Bokha stream using various measures which include BMPs approach and change of landuse. The evaluation of reduction of non-point source pollution was developed using load-duration curve. Despite strong reduction of non-point source, there are not satiated target quality at low flow season.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.9
• /
• pp.1073-1080
• /
• 1999

Optimal routing of distribution networks can be attained by keeping the line power capacity limit to handle load requirements, acceptable voltage at customer loads, and the reliability indices such as SAIFI, SAIDI, CAIDI, and ASAI limits. This method is composed of optimal loss reduction and optimal reliability cost reduction. The former is solved relating to the conductor resistance of all alternative routes, and the latter is solved relating to the failure rate and duration of each alternative route. The routing considering optimal loss only and both optimal loss and optimal reliability cost are compared in this paper. The case studies with 10 and 24 bus distribution networks showed that reliability cost should be considered as well as loss reduction to achieve the optimal routing in the distribution networks.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.10 no.1
• /
• pp.7-11
• /
• 2010

In this paper, we propose an improved speech/music discrimination method based on a feature combination and dimensionality reduction approach. To improve discrimination ability, we use a feature based on spectral duration analysis and employ the hierarchical dimensionality reduction (HDR) method to reduce the effect of correlated features. Through various kinds of experiments on speech and music, it is shown that the proposed method showed high discrimination results when compared with conventional methods.

• Advances in pediatric surgery
• /
• v.15 no.2
• /
• pp.132-140
• /
• 2009

The purpose of this study was to determine the success rate of air reduction as the primary treatment of intussusception and whether the success of air reduction could be predicted by plain x-ray. The authors reviewed the medical records of 54 consecutive patients diagnosed with intussusception from Jan 2005 to Dec 2007 at the Department of Surgery, Masan Samsung Hospital. The natures of symptoms and findings of plain abdominal radiography performed in the emergency department (ED) were reviewed. Air reduction failed more frequently (26.3 %) in patients who visited ED more than 24 hours after symptom onset (p=0.009). The mean duration of symptom for operated patients was longer than air reduction group (p=0.01). Also, 3/4 of patients having localized distension of small bowel in the left upper quadrant abdomen had unsuccessful air reduction (p=0.002). In conclusion, the time interval from symptom onset to arrival at ED and localized distension of small bowel in the left upper quadrant abdomen significantly increased the failure rate of air reduction.

• Korean Journal of Construction Engineering and Management
• /
• v.7 no.2 s.30
• /
• pp.109-117
• /
• 2006

Recent rapid changes such as construction market reduction, lowest bidding system of construction cost, five days per week system, and post-construction sale system are inevitably accelerating the competitiveness between construction companies. Those rapid changes of construction environment require construction companies, which are main participants of construction industry, to adapt to the changes and more to lead new construction environment. However, there are many construction uncertainties which could delay construction completion. Without the proper identification of construction uncertainties, structured strategy establishment and management of construction schedule, the competitive advantages of construction duration could not be made. Thus this paper limited the research boundary to construction duration competitiveness instead of general strategy establishment. Recognizing the importance of proper calculation of construction duration, requirements of construction duration reduction and limited researches related to construction schedule strategy, we established the 25 strategies for construction duration competitivenss by internal and external construction environment analysis and SWOT analysis, and then elicited the first considerations to accomplish the strategies through concensus of all the staffs by questionnaire, brainstroming and face-to-face interviews.

• ETRI Journal
• /
• v.35 no.1
• /
• pp.80-88
• /
• 2013

A passive infrared or pyroelectric infrared (PIR) sensor is mainly used to sense the existence of moving objects in an indoor environment. However, in an outdoor environment, there are often outbreaks of false alarms from environmental changes and other sources. Therefore, it is difficult to provide reliable detection outdoors. In this paper, two algorithms are proposed to reduce false alarms and provide trustworthy quality to surveillance systems. We gather PIR signals outdoors, analyze the collected data, and extract the target features defined as window energy and alarm duration. Using these features, we model target and false alarms, from which we propose two target decision algorithms: window energy detection and alarm duration detection. Simulation results using real PIR signals show the performance of the proposed algorithms.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.18 no.3
• /
• pp.88-94
• /
• 2010

In this paper, the effect of the ultrasonic energy on the diesel engine's smoke reduction has been investigated for indirect injection diesel engine. The smoke concentration of the ultrasonically reformed diesel fuel was reduced remarkably in comparison with conventional diesel fuel. And in-cylinder pressure, heat release rate and mass fraction burned was improved but combustion duration was decreased. However, The combustion durations and the smoke concentrations of both diesel fuels were proportional to the increases of engine loads. Also, When the combustion duration has been increasing, the smoke emission has been augmenting in the shape of the exponential functions.

• Journal of Korean Foot and Ankle Society
• /
• v.10 no.2
• /
• pp.190-195
• /
• 2006

Purpose: To evaluate the results of open reduction and internal fixation for displaced talar neck fracture. Materials and Methods: Fourteen patients were followed for more than 1 year after open reduction and internal fixation of displaced talar neck fracture. The mean age was 41.5 years, and the mean follow-up period was 3.8 years. There were 10 type II, 3 type III and 1 type IV fractures per Hawkins. There were 3 open fractures. Clinically AOFAS ankle-hindfoot scale and Hawkins criteria were utilized. Radiologically quality of reduction, duration of bony union, avascular necrosis and posttraumatic arthritis were evaluated. Results: At last follow-up, AOFAS scale was mean 89.1 points. There were 8 excellent, 4 good, and 2 fair results according to Hawkins criteria. Radiologically anatomical reduction was obtained in 13 cases. Mean duration of bony union was 11.8 weeks. There were 3 avascular necrosis and 2 post-traumatic arthritis. There was no significant difference in the incidence of avascular necrosis between early operation group and surgically delayed group. Conclusion: Accurate open reduction and rigid internal fixation seem to be prerequisites for satisfactory treatment of a displaced talar neck fracture.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.60 no.6
• /
• pp.97-109
• /
• 2018

The LDC (Load Duration Curve) method can analyze river water quality changes according to flow rate and seasonal conditions. It is also possible to visually recognize whether the target water quality is exceeded or the size of the reduction load. For this reason, it is used for the optimal reduction of TPLCs and analysis of the cause of water pollution. At this time, the flow duration curve should be representative of the water body hydrologic curve, but if not, the uncertainty of the interpretation becomes big because the damaged flow condition is changed. The purpose of this study is to estimate the daily mean flow of the unit watershed using the HSPF model and to analyze the difference of the flow duration curves according to the cumulative daily mean flow rate using the NSE technique. The results show that it is desirable to construct the flow duration curve by using the daily average flow rate of at least 5 years although there is a difference by unit watershed. However, this is the result of the water bodies at the end of Han River basin watershed, so further study on various water bodies will be necessary in the future.