• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.9
• /
• pp.1045-1050
• /
• 2014

$N_2O$(Nitrous Oxide) is known as the third major GHG(Green House Gas) following $CO_2$(Carbon Oxide) and $CH_4$(Methane). The GWP(Global Warming Potential) factor of $N_2O$ is 310 times as large as that of $CO_2$ because $N_2O$ in the atmosphere is very stable, and it becomes a source of secondary contamination after photo-degradation in the stratosphere. Investigation on the cause of the $N_2O$ formation have been continuously reported by several researchers on power sources with continuous combustion form, such as a boiler. However, in the diesel engine, research on $N_2O$ generation which has effected from fuel components has not been conducted. Therefore, in this research, author has investigated about $N_2O$ emission rates which was changed by nitrogen and sulfur concentration in fuel on the diesel engine. The test engine was a 4-stroke direct injection diesel engine with maximum output of 12 kW at 2600rpm, and operating condition of that was set up at a 75% load. Nitrogen and sulfur concentrations in fuel were raised by using six additives : nitrogen additives were Pyridine, Indole, Quinoline, Pyrrol and Propionitrile and sulfur additive was Di-tert-butyl-disulfide. In conclusion, diesel fuels containing nitrogen elements less than 0.5% did not affect $N_2O$ emissions in the all concentrations and kinds of the additive agent in the fuel. However, increasing of the sulfur additive in fuel increased $N_2O$ emission in exhaust gas.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.17 no.2
• /
• pp.72-77
• /
• 2013

Purpose: Whole-body PET using radiopharmaceutical is one of the imaging study methods for physiological changes of body. High specificity of the PET-CT examination is used to detect an early stages of cancer and metastatic cancer by imaging a physiological changes. During the imaging process, PET image has been characterized by a relatively low image quality due to its low sensitivity and the acquisition of random and scatter coincidences as well as patients figure. Therefore, the image quality as the changes of the acquisition times of patient weight was evaluated in this study. Materials and Methods: Thirty patients who presented to our hospital were enrolled. They were divided to normal, overweight, and obese group using BMI index, respectively. The patients with a liver disease and diabetes were excluded. $^{18}F-FDG$ was administered to the patients as 5.2 MBq per kg. After an hour from an injection, image acquisition was obtained as List mode in a part of liver in 1 bed. SNR (signal-to-noise ratio) of each groups acquisition times were confirmed from the calculated radiation counts and random fractions. The statistical significance of three groups was confirmed through one-way ANOVA test. On the basis of the counts of 2 minutes on normal group, the SNR of overweight group and obese group were compared. Results: The SNR were increased with loger aquisition time in 3 groups. In the condition of same acquisition time, the SNR had a statistical significance (P<0.05). The SNR were decreased to the normal, overweight, and obese, respectively. Liver activity had no significance difference on each group and RF had the significance differences (P<0.05). On the basis of the counts of 2 minutes on normal group, there were no statistical significance in a three minute acquisitions of overweight group and two minute acquisitions of obese group (P=0.150). Conclusion: In this study, the administrated amount of radiation dose did not adjust as the change of the patients weight. Increasing the acquisition time when the administration of the same amount of dose was able to get a good result of SNR. When the Based 2 minute on normal group, if overweight and obese case the increased acquisition time of 3 minute was able to obtain a similar SNR. On the basis of the normal group, the acquisition times of overweight and obese group were increased to 3 minutes per bed and the SNR were similar to the normal group.

• Journal of Energy Engineering
• /
• v.25 no.4
• /
• pp.159-169
• /
• 2016

In this study, the effects of MTBE contents as oxygenates in gasoline on exhaust emissions and fuel economy in MPI and GDi vehicles have been investigated. Various oxygen contents have been selected such as 0, 1.0, 2.3 and 2.7 wt%. FTP-75 and HWFET modes as fuel economy test methods which are widely used in Republic of Korea and US were applied to investigate exhaust emissions from the test vehicles. Emissions of CO, NMHC and NOx did not show significant correlation with oxygen contents in gasoline fuels, although having slight difference with these contents. In addition, CO2 emissions were not significantly changed with respect to oxygen content. But in case of warm-up and FTP-75 and HWFET modes including high speed regimes, CO2 emissions showed inverse correlation with oxygen contents. Particulate number concentration was inversely proportional to the oxygen contents, having the minimum value at the condition of 2.3 wt%. In case of fuel economy through carbon balance method, the highest value has been obtained at 2.3 wt% and there was positive correlation with oxygen contents and fuel economy.

• Tunnel and Underground Space
• /
• v.8 no.3
• /
• pp.209-225
• /
• 1998

Recently, Umbrella Arch Method(UAM), one of the auxiliary techniques for tunnelling, is used to reinforce the ground and improve stability of tunnel face. Because UAM combines the advantages of a modern forepoling system with the grouting injection method, this technique has been applied in subway, road and utility tunnel sites for the last few years in Korea. Also, several research results are reported on the examination of the roles of inserted pipes and grouted materials in UAM. But, because of its empirical design and construction methodology, more qualitative and systematic design sequences are needed. Therefore, above sequences using numerical analysis are proposed and, the effects of some design parameters were studied in this research. In order to acco,mplish these objects, first, the roles of pipe and grouting materials, steel-rib and the others in ground improving mechanism of UAM are clarified. Second, the effects of design parameters are investigated through parametric studies. Design parameters are as follows; 1) ground condition, 2) overburden, 3) geometrical formulation of pipes, 4) grouting region and 5) characteristics of pipes.

• Tunnel and Underground Space
• /
• v.23 no.4
• /
• pp.297-307
• /
• 2013

In this study, the thermal analysis is carried out for a result of borehole heater test using ABAQUS ver 6.10 based on finite element analysis code. Thermal-mechanical rock properties as determined by laboratory tests before the in situ test and characteristics of the atmosphere at the test section are used as the initial condition. When comparing the results of the in situ test and thermal analysis, the temperature of C3 observation hole that is 0.9 m away from the heater showed very similar patterns and figures (about $1.3^{\circ}C$ difference). But the results of the A and B observation hole showed a significant difference around $15^{\circ}C{\sim}20^{\circ}C$. To find the reason for these results, the over-coring is carried out for the A1 and B1 observation holes. As a result of checking the excavated rock core with the naked eye, there is no problem on the number and position of the sensor as the test plan. However the state of cement injection in the observation hole is poor.

• The Journal of Korean Academy of Prosthodontics
• /
• v.56 no.3
• /
• pp.199-205
• /
• 2018

Purpose: This study evaluated the effect of nonthermal plasma treatment on the bond strength of autopolymerizing relining resin to the injection molded thermoplastic denture base resins (TDBRs) with different surface treatments. Materials and methods: Acrylic Resin (Acrytone), Polyester (Estheshot-Bright), Polyamide (Valplast) and Polypropylene (Weldenz) were subjected to various surface treatments: No treatment, Nonthermal plasma, Sandblasting, Sandblasting and nonthermal plasma. Specimens were bonded using an autopolymerizing relining resin. Shear bond strength was tested using universal testing machine with crosshead speed of 1 mm/min. Statistical analysis by two-way analysis of variance with Tukey's test post hoc was used. Results: Acrytone showed significantly higher shear bond strength value among other TDBR group while Weldenz had the lowest. The sandblasting and nonthermal plasma condition had significantly higher shear bond strength value in all of the resin groups (P < .05). Conclusion: The use of nonthermal plasma treatment showed limited effect on the shear bond strength between TDBRs and relining resin, and combination of nonthermal plasma and sandblasting improved the shear bond strength between TDBR and reline material.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.32 no.6
• /
• pp.544-558
• /
• 2006

Trismus is a common problem to most people experiencing at once in his or her life and to most dental practitioners experiencing frequently. It has a number of potential causes which are single factor or complex factors. Its treatment will depend on the cause. The purpose of this study was to discuss the causes of trismus condition and the various treatments available. This study was made by reviewing of collected data from 86 patients complained of trismus among patients who were diagnosed by TMD, tumor, infection including tetanus, soft tissue anomalies, bony fracture and ankylosis from Jan 2002 to Dec 2004 on department of oral and maxillofacial surgery at Pusan National University Hospital, South Korea. The clinical reviews regarding chief complaints, clinical characteristics, diagnostic examination, treatments and the results on the patients were given as follows. 1. The etiology of trismus commonly were derived from temporomandibular joint(TMJ) disorder, TMJ ankylosis, TMJ tumor, odontogenic maxillofacial infection, mandibular condylar fracture, tetanus. 2. The chief complaints of trismus patients were progressive mouth opening limitation, TMJ pain, malocclusion, facial asymmetry, retrognathic state. 3. Especially, for the differential diagnosis between the fibrous ankylosis and true bony ankylosis, computed tomogram (CT) was useful. Surgical gap arthroplasty on bony ankylosis patients was applied and the gain of mouth opening after operation was average 35.8 mm during 19 months. 4. The tetanus, rarely, also induced the trismus with the range of mouth opening less than 10 mm. The average serum level of tetanus anti-toxin was 0.02-0.04 IU/mL. The limitation of mouth opening was improved into average 38 mm on 4 weeks after injection of 10,000 units of tetanus immune globulin. 5. In the treatment of osteochondroma, TMD, odontogenic infection and fracture, and the others inducing trismus, to obtian the maximum result and decreased inadequate time and effort, it is important to finding the causes from the exact clinical examination and diagnosis.

• Tunnel and Underground Space
• /
• v.22 no.6
• /
• pp.403-411
• /
• 2012

In recent, the using of the hydraulic filling method has increased on the underground reinforcement of the abandoned mine in Korea, however it is the lack of research on the efficient filling method. In this study, tank model tests and field tests were conducted for development of tip device for filling efficiency improvements on the hydraulic filling method. In tank model experiments, the filling efficiency was evaluated according to the form and angle of the nozzle on tip device in the same condition. Then tip device model designed by tank model tests was applied to the field experiment. As a result, the amount of filling of nozzle $90^{\circ}$ tube is increased by approximately 18% compared to the common vertical injection pipe. The angle of repose was $30.82^{\circ}$. Filling hole spacing in the field is usually designed from 5m up to 10m assumed to be $40^{\circ}$ of the angle of repose. According to the results of this study, it is possible that the filling hole spacing expands at least 10m up to 15m applied to be $30^{\circ}{\sim}35^{\circ}$ of the angle of repose. Therefore, it is expected to be economical and efficient mine filling.

• Tunnel and Underground Space
• /
• v.24 no.4
• /
• pp.297-307
• /
• 2014

Cavern Thermal Energy Storage system stores thermal energy in caverns to recover industrial waste heat or avoid the sporadic characteristics of renewable-energy resources, and its advantages include high injection-and-extraction powers and the flexibility in selecting a storage medium. In the present study, the structural stability of rock mass pillar between these silo-type storage caverns was assessed using a coupled thermal-mechanical model in $FLAC^{3D}$. The results of numerical simulations showed that thermal stresses due to long-term storage depended on pillar width and had significant effect on the pillar stability. A sensitivity analysis of main factors indicated that the influence on the pillar stability increased in the order cavern depth < pillar width < in situ condition. It was suggested that two identical caverns should be separated by at least one diameter of the cavern and small-diameter shaft neighboring the cavern should be separated by more than half of the cavern diameter. Meanwhile, when the line of centers of two caverns was parallel to the direction of maximum horizontal principal stress, the shielding effect of the caverns could minimize an adverse effect caused by a large horizontal stress.

• Korean Journal of Veterinary Research
• /
• v.47 no.1
• /
• pp.103-115
• /
• 2007

The aim of this study was to compare the reaction of the cardiovascular system, and the anesthetic effect among 3 experimental groups, epidural administration of medetomidine as a single agent, the combination of buprenorphine and medetomidine, and the combination of fentanyl and medetomidine. Twenty one dogs were anesthetized with isoflurane and allowed to breathe spontaneously. Epidural, arterial, and venous catheters were inserted. The tip of epidural catheter was positioned at the level of the space between the sixth and seventh lumbar vertebra. After a stable plane of anesthesia was achieved, these dogs were each administered one of the following treatments epidurally : medetomidine $10{\mu}g/kg$ (Group M), a combination of medetomidine $5{\mu}g/kg$ and buprenorphine $10{\mu}g/kg$ (Group M/B), and a combination of medetomidine $5{\mu}g/kg$ and fentanyl $10{\mu}g/kg$ (Group M/F). Heart rate (HR), Respiratory rate (RR), End-tidal carbon dioxide (EtCO2), and arterial blood pressure were measured before drug administration (base line) and 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 min postinjection. Blood gas analysis was performed before injection and 5, 15, 25, 35, 45, 60 min postinjection. Isoflurane was discontinued 80 min postinjection and pain/motor function were evaluated up to 260 min postinjection every 15 min. At the early stage of drug introduction (until 5 min), the HR was decreased significantly in all 3 groups compared with base line. In Group M, HR was significantly decreased compared with the other 2 groups. With time (starting 20 min after drug introduction), the HR was decreased significantly in Group M/B in respect to base line. However, no significant difference was seen number-wise in all 3 groups. During 60 min after drug introduction, the systolic, diastolic and mean arterial pressures were highest in Group M and lowest in Group M/F. Among 3 groups, drug action and motor loss duration were longest in Group M/F. Analgesic effect observed in the M/F group was the most prominent and long-lasting, compared to those seen in the other 2 groups. Given the fact that the recovery of motor function takes place in a short period of time after analgesic effects disappeared, additional use of M/F depending on the patient's condition would be a good way to achieve effective pain management. However, proper care should be taken to ensure the function of cardiovascular system in the patient because the administration of M/F under isoflurane anesthesia results in a significant decline in arterial blood pressure ($65{\pm}10mmHg$).