• Journal of ILASS-Korea
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• v.20 no.4
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• pp.217-222
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• 2015

In this study, Injection rate tests of a Diesel common-rail injector have been performed with injection volume measurement type injection rate test system EMI21 for construction of injector model can be used in an engine calibration mean valued model. The measuring principle of the test system is based on measurement of dispalcement of a movable measurement piston by the volume of fluid released by the injector. From these injection rate test results, the characteristics on shape of instantaneous injection rate and injection fuel amount have been investigated and injection fuel amount calculation equation based on test results has been newly constructed. This equation is very simple and calculation error is less than 5% with test results for wide range injection pressure (200~1800 bar) and injection duration ($200{\sim}1800{\mu}s$) conditions. So, it is anticipated that newly constructed simple injection fuel amount model in this study can be efficiently used on engine calibration and control model.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.1
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• pp.60-71
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• 1999

This study was performed to improve underirable warm greenhouse environment by fog cooling system in summer season. The resultsof droplet size analysis and cooling effects for fog cooling system are summarized as follows ; 1. At the pump pressure of 70kgf/$\textrm{cm}^2$ , the mean (SMD) drop size was 22.6${\mu}{\textrm}{m}$ and the maximum and minimum drop size was 45.68${\mu}{\textrm}{m}$ and 1.73${\mu}{\textrm}{m}$ , respectively, and almost all of the drop size was less than 40${\mu}{\textrm}{m}$. 2. The temperature of fog cooling greenhouse with 60% shading was dropped more than 2$^{\circ}C$ below the ambient temperature , while the greenhouse temperature without shading was 1$^{\circ}C$ higher than the ambient temperature. 3. It was found that fog spraying intervals were significantly influential on cooling effect. 4. When the greenhouse was ventilated sufficiently by natural vent system, green house temperature could be maintained by 2.5$^{\circ}C$ lower than the ambient temperature, while it was difficult to drop the greenhouse temperature below ambient temeperature without sufficient ventilation. 5. It was found that the temperature of experimental greenhouse could be maintained 3$^{\circ}C$ to 14$^{\circ}C$ lower that of control greenhouse though there were variations depending on experimental and weather conditions.

• Korean Journal of Veterinary Research
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• v.45 no.3
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• pp.423-427
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• 2005

Color Doppler imaging (CDI) was carried out to evaluate the anesthetics effect on ophthalmic circulation using CDI-derived resistive index (RI) values. CDI was preformed on 24 dogs, and RI values were calculated for the medial long posterior ciliary artery (mLPCA) and ophthalmic artery (OA) before and after administration of anesthetics. After administration of benoxinate or acepromazine, a significant change of the mLPCA RI was not found. But, a significant decrease of the RI following ketamine (p < 0.001) or xylazine (p < 0.01) administration could be observed as compared with the self-control. Mean RI value of OA also showed this same trend. Intraocular pressure was significantly decrease following benoxinate (p < 0.01), acepromazine (p < 0.01), and xylazine (p < 0.001) administration within normal range. The results suggest that some anesthetics influence on ophthalmic vascular resistance. Therefore, chemical restraint was carefully used in clinical application of CDI-derived RI measurement. Particularly, benoxinate and acepromazine is useful chemical restraint without a change of the ophthalmic vascular resistance.

• Journal of Powder Materials
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• v.2 no.1
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• pp.29-35
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• 1995

In this study the calcined condition and characteristic of Cu-Ni-Zn ferrite powder were investigated. The Cu-Ni-Zn ferrite powder has been synthesized by the thermal decomposition of the organic acid salt. This process did not require a strict pH control and provided the uniform composition and fine powder with about 0.3 $\mu\textrm{m}$. The XRD diffraction pattern of this powder showed about 50% spinel phase. The optimum calcination was found to be done at $700^{\circ}C$ for one hour. After the calcination, the amount of spinel increased to 90%. The distribution of the particle size showed bimodal peaks, one was about 0.5 $\mu\textrm{m}$ and the other was about 20 $\mu\textrm{m}$. The large particles of 20 $\mu\textrm{m}$ were the agglomeration of fine Particles. The mean Particle size of the powder was about 0.4 $\mu\textrm{m}$. The powder was compacted under 100 MPa pressure and sintered at 1100~ $1250^{\circ}C$ for one hour in air. The density of ferrites specimen was a function of the sintering temperature. The higher the temperature, the denser the ferrite. The maximum relative density of the sintered ferrite was about 93% at $1250^{\circ}C$. The grain size of sintered specimen at $1200^{\circ}C$ was 5 $\mu\textrm{m}$ and homogeneous.

• Journal of Korean Public Health Nursing
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• v.22 no.1
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• pp.27-38
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• 2008

Purpose: To determine the degree of cardiovascular disease risk according to socioeconomic factors among midlife women in the community and thereby provide baseline data for the development of health promotion programs. Method: A total of 200 women participated in health screenings and a health survey. The survey was performed in November and December, 2006. The survey instruments included socioeconomic factors, health behavior (smoking and exercise), and family history. Biophysical measurement included BMI and blood pressure. Blood samples were drawn for glucose and total cholesterol tests. Results: The mean age was 52.5 years, 34.0% had received education less than 6 years, 70.0% earned a monthly income of less than \1,500,000, and 61.5% were homemakers. Cardiovascular disease risk was significantly different by age (BMI, systolic BP, and exercise), education (systolic BP), monthly income (T. cholesterol), marital status (smoking), and occupation (exercise). Most women had 2 or 3 cardiovascular disease risks. Older age, lower education, and lower income were significantly associated with increased cardiovascular disease risk. Conclusion: Efforts should be made to decrease the number and severity of cardiovascular disease risk factors for midlife women in the community by developing health promotion programs targeting to modify their cardiovascular disease risk factors.

• Journal of Korean Academy of Nursing
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• v.35 no.4
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• pp.694-700
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• 2005

Purpose. The purpose of this study was to determine the relationship between peer and parental factors and smoking behavior of adolescents in urban cities and to investigate whether there are gender differences. Methods. A stratified and random cluster sampling design was used to obtain a cross-sectional sample of high school students in two urban cities. The sample consisted of 512 Korean adolescents (256 boys and 256 girls) aged 15 to 18 (mean age 16.7$\pm$.58). Self-reported questionnaire consisted of adolescent smoking behavior, peer smoking and alcohol use, parental smoking and alcohol use, father-mother-peer relationships and perceived social support from peers and parents. Multiple logistic regression analysis was used to examine the hypothesized model. Results. The findings showed that peer and parental factors accounted for $30.3\%$ of the variance in adolescent smoking and peer smoking was most strongly associated with adolescent smoking behavior (OR = 10.18). In addition, peer smoking (OR = 4.71), peer alcohol use (OR = 4.21), and peer relationships (OR = 1.03) were significantly associated with boys' smoking behavior. In girls, peer smoking (OR = 26.50) and parent smoking (OR = 5.48) were significantly associated with smoking behavior. Conclusions. Consistent with previous findings, peer smoking is a significant factor on adolescent smoking. Specifically, boys would be more influenced from peers than girls. Therefore, smoking prevention programs for adolescents might be focused on the social context such as, resisting to peer pressure and enhancing the self-efficacy to control.

• Journal of Drive and Control
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• v.19 no.4
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• pp.29-35
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• 2022

In this paper, we developed a workload index for monitoring the durability test using operation information of an excavator. First, the acceleration and cylinder pressure were selected as load factors by analyzing operation data. Through load correlation analysis according to each load factor, Root Mean Square (RMS) and Work Load Range (WLR) were respectively derived as a load feature representing mechanical load. In addition, the workload index was used to quantify load features. For applying the workload index to monitoring, a real-time monitoring system consisting of sensors and embedded controller was installed on the excavator and the system was integrated with a remote monitoring environment using a wireless network. Results of load monitoring and analysis verified that the developed workload index was effective from the viewpoint of the relative comparison of the workload.

• Journal of Society of Preventive Korean Medicine
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• v.19 no.3
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• pp.155-170
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• 2015

Objective : Jaeumgeonbitang have been used in Korean medicine for many centuries as a therapuetic agent of vertigo. JAE was extract of Jaeumgeonbitang adding Evodiae Fructus. The effects of JAE on the cerebral blood flow and blood pressure is not known. This study was designed to investigate the effects of JAE on the ischemic crebral injuries. Method : We performed to investigate effects of JAE on the changes of regional cerebral blood flow(rCBF) and mean arterial blood pressure (MABP) in normal and ischemic rats, and further to determine the mechanism and cytokines production ($IL-1{\beta}$, $TNF-{\alpha}$, IL-10, $TGF-{\beta}$) of JAE. Results : In normal rats, JAE significantly increased rCBF and significantly decreased MABP in a dose-dependent manner. This result suggested that JAE significantly increased rCBF by dilating pial arterial diameter. Increase of JAE-induced rCBF was significantly inhibited by the pretreatment with indomethacin (1 mg/kg, i.p.), an inhibitor of cyclooxygenase, and was significantly inhibited by methylene blue ($10{\mu}g/kg$, i.p.), an inhibitor of guanylate cyclase. Decrease of JAE-induced MABP was significantly increased by the pretreatment with indomethacin (1 mg/kg, i.p.), an inhibitor of cyclooxygenase. So, these results suggested that the mechanism of JAE was mediated by cyclooxygenase. In ischemic rat, the rCBF was significantly and stably increased by JAE (10 mg/kg, i.p.) during the period of cerebral reperfusion, which contrasted with the findings of rapid and marked increase in Control group. In cytokine production of serum by drawing from femoral arterial blood at 1 hr after reperfusion, Sample group (JAE 10 mg/kg treated group) was significantly decreased $IL-1{\beta}$ and $TNF-{\alpha}$ production compared with Control group. In cytokine production of serum by drawing from femoral arterial blood at 1 hr after reperfusion, Sample group was significantly increased IL-10 production compared with Control group. Conclusion : These results suggested that JAE was significantly and stably increased regional cerebral blood flow by inhibited $IL-1{\beta}$ and $TNF-{\alpha}$ production, and increased IL-10 production.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.61-75
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• 1997

The bond strengths of composite resin to tooth dentin vary with the methods of cavity preparation and surface treatment. Recent developments in techniques of dentinal surface treatment have renewed interest in microabrasive as a means of tooth preparation, The purpose of this study was to determine the effects of a new method of cavity preparation on the bond of composite resin to dentin. Freshly extracted 144 healthy human third molars were used in this study. The dentin surfaces prepared with #600 SiC abrasive paper were divided into control and air abrasion groups according to the method of dentin surface preparation using different combinations of delivery pressure, time, and acid etching. The shear bond strengths were measured after the composite resin (Clearfil Photo Bright) was bonded to prepared dentin surfaces by light-curing using a dentin bonding system (All-bond 2), In addition, the average surface roughness was measured to investigate the effect of differently prepared dentin surfaces on the shear bond strengths. The surface changes of prepared dentin and the debonded dentin surfaces were observed with SEM (S-2300, Hitachi Co., Japan). The following results from this-study were obtained ; 1. There was no significant difference of shear bond strengths according to the changes of delivery pressure and time. 2. The shear bond strengths were lower than the control in the air abraded-only groups, but those of the additional acid-etched groups were higher than the control. 3. The shear bond strengths to all air-abraded surfaces were increased by acid etching. 4. The correlation between shear bond strengths and surface roughness was not certain, although the mean surface roughness of all air-abraded surfaces has increased evidently while it has slightly decreased for additional acid etching. 5. On SEM examination, the dentinal tubules were almost occluded in the air abraded-only groups, but those were opened in the additional acid-etched groups. 6. The debonded surfaces were showed adhesive failure mode in the air abraded- only groups, while those were showed mainly the mixed and cohesive failure mode in the additional acid-etched groups. These results suggest that the layer produced during cavity preparation or surface treatment with air abrasion must be removed for maximum bond strength of composite resin to dentin.

• Journal of Drive and Control
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• v.13 no.2
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• pp.10-18
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• 2016

A front-end loader (FEL) mounted on an agricultural tractor is one of the most commonly used implements to mechanize routine agricultural tasks. When the FEL is used with a loaded bucket, careful operation is required to maintain safety and avoid spillage when the tractor passes a bump because a change in the gravity center of the tractor due to varied loadings can affect the stability of the tractor. Use of a boom suspension system consisting of accumulators and orifice dampers can be instrumental in reducing pitching vibrations while increasing the handling performance of the FEL-mounted tractor. The objective of this research was to reduce bump shocks by adding an orifice and a flow control valve to the original hydraulic circuit composed solely of accumulators. A simulation study was performed using the SimulationX program to investigate the effects of an accumulator and an orifice-throttle damper on bump shocks. Results showed that the peak pressure on a boom cylinder and the vertical acceleration of a bucket were significantly affected by use of both an accumulator and an orifice damper. In a field test conducted with a 75-kW tractor, the peak pressure of the boom cylinder, and the root mean square (RMS) vertical acceleration of the bucket and seat were reduced by on average, 23.0, 42.2, and 44.9% respectively, as compared to those measured with the original accumulator system, showing that an improved design for the accumulator hydraulic circuit can reduce bump shocks. Further studies are needed to design a tractor suspension system that includes the effects of cabin suspension and tires as well as dynamic analysis.