• Korean Journal of Food Science and Technology
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• v.5 no.2
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• pp.129-135
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• 1973

The accumulation of peroxides, acid values, and carbonyl values during irradiation and post-irradiation storage of the ricebran oil has been studied. The rice bran oils were irradiated two doses of 2 and 7 megarads (300 rads/sec) at $23^{\circ}C$ atmospheric circumstance. The acid values, peroxide values and carbonyl values were measured at regular intervals of one week during the storage at $5^{\circ}C$ and $25^{\circ}C$. 1) During the storage, the acid values of the irradiated rice bran oils increased or decreased insignificantly regardless of the addition of antioxidants and storage temperature. 2) The peroxide values were not increased continuously but increased zigzag. The result was indicated that the composition and decomposition of peroxides occurred continuously throughout the storage. 3) As the peroxide values increased, carbonyl values decreased and changed quite differently, but, especially in 7th week, they were constant or insignificant. 4) Dibutylhydroxytoluene is more effective than caffeic acid in retarding the formation of peroxides during irradiation of rice bran oils and post-irradiation storage. The effect of antioxidant is more efficient at 2 megarads than at 7 megarads irradiation. When we store the rice bran oil, the addition of antioxidants of post-irradiation is more desirable than that of preirradiation. 5) In spite of changing conditions such as storage temperature and addition of antioxidants, the peroxide values of rice bran oils irradiated at 2 megarads were always greater than those at 7 megarads during the storage. Peroxide values of samples at high temperature $(25^{\circ}C)$ storage increased as twice as those of low temperature $(5^{\circ}C)$ storage samples. At low temperature, peroxide values in the first week increased twice during the period of 8th weeks storage, but those did from three to four times at higher temperature in the same period Therefore, the low temperature storage is recommandable too.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.2
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• pp.161-170
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• 1997

This is an effort to confirm changes biological monitoring according to changes in levels of exposure to styrene for industrial workers. This study was conducted on 108 workers, including male of 64 and female 44 who were working at factories of FRP, dipping, and coating. An improved passive monitor method(organic vapor monitor; OVM) was employed to determine levels of exposure. The biological monitoring include blood styrene concentration, urinary mandelic acid(MA), and urinary phenylglyoxylic acid(PGA). Biological monitoring were made through the Collection of blood and urine. The mean value of exposure to styrene was 21.0ppm, which is measured by organic vapor monitor, one of improved passive monitors. The highest exposure level was observed among workers in boat factories, laminating procedure workers, processing workers, respectively(p<0.01). For exposure level, 11% of subjects under study showed over 50ppm which is time weighted average(TWA). The correlation coefficient between biological specimens and the exposure level was 0.62 for blood styrene concentration, 0.58 for MA corrected by creatinine, and 0.70 for PGA corrected by creatinine, respectively(p<0.01). The regression analyses found exposure level relative importance in explaining variance in biological monitoring. In additional to that, gender was a significant factor in explaining variance of MA and MA+PGA. Almost half of variance(49%) in blood styrene concentration was explained by predictors, including exposure level, age, gender, duration, and drinking volume during the last week(p<0.01). The very high correlation(higher than 0.95 was found when a comparison was made among three types of corrected methods, including uncorrected specific gravity and creatinine. In conclusion, these findings suggest OVM to represent levels of exposure to styrene for industrial workers. A discussion was made on possible use of specific gravity sample for biological monitoring. Exposure level may be predicted on MA, PGA in urine, which could be applied to represent biological monitoring.

• Tuberculosis and Respiratory Diseases
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• v.40 no.5
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• pp.540-547
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• 1993

Backgrounds: The measurement of volume of isoflow has been considered as a sensitive test for detecting small airway diseases showing normal pulmonary function in a routine pulmonary function test. To evaluate the functions of small airway among dust exposed workers, the changes of volume of isoflow were measured and its applicability of managing early stage pneumoconiosis patients was studied. Method: The subjects were 67 male, pneumoconiosis with small opacity and FEV1>80%, FEV1/FVC>75% in spirometry and the controls were 20 male, no dust-exposed office workers. The maximal epiratory volume curves after inhalation of indoor air and $He-O_2$ gas mixtures were measured and ${\Delta}V_{max50},\;{\Delta}V_{max75},\;V_{iso}V/VC$ between the dust exposed and control workers were compaired. Results: 1) There were no significant differences between two group in ${\Delta}V_{max50}$ and ${\Delta}V_{max75}$. But the ratio of $V_{iso}V/VC$ of the subjects was siginificantly higher than that of the control (p<0.01). This study confirms that $V_{iso}V/VC$ is a very useful index in early detection of small airway dysfunction. 2) The ratio of $V_{iso}V/VC$ of the subjects was signigicantly different between only smoker group and mixed group(smoker and nonsmoker). It suggestes that smoking is an important cousative factor of small airway dysfunction. 3) As the profusion of the chest X-ray increased, the rartio of $V_{iso}V/VC$ increased, but no significant difference of $V_{iso}V/VC$ was found between categories of pneumoconiosis. The categories of pneumoconiosis and small airway dysfunction may not be related. 4) No significant relationship was established between the duration of work and the ratio of $V_{iso}V/VC$. Conclusions : It is concluded that the measurement of $V_{iso}V/VC$ is useful to detect small airway dysfuction of early stage pnuemoconiosis patents with small opacities but showing normal pulmonary function in a routine pulmonary function test.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.3
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• pp.179-187
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• 2018

Purpose: The purpose of this study was to investigate the effect of heat applied to disintegrate cement on the removal torque value and fracture strength of titanium abutment and abutment screw. Materials and methods: Implants, titanium abutments and abutment screws were prepared for each 20 piece. Implant abutments and screws were classified as the control group in which no heat was applied and the experimental group was heated in a vacuum furnace to $450^{\circ}C$ for 8 minutes and cooled in air. The abutments and screws were connected to the implants with 30 Ncm tightening torque at interval 10 minutes and the removal torque value was measured 15 minutes later. And the fracture strength of abutment screw was measured using universal testing machine. Results: The mean removal torque value was $27.84{\pm}1.07Ncm$ in the control group and $26.55{\pm}1.56Ncm$ in the experimental group and showed statistically significant difference (P < .05). The mean fracture strength was $731.47{\pm}39.46N$ in the control group and $768.58{\pm}46.73N$ in the experimental group and showed statistically no significant difference (P > .05). Conclusion: The heat applied for cement disintegration significantly reduced the removal torque value of the abutment screw and did not significantly affect fracture strength of the abutment screw. Therefore, in the case of applying heat to disintegrate cement it is necessary to separate the abutment screw or pay attention to the reuse of the heated screw. However further studies are needed to evaluate the clinical reuse of the heated screw.

• The Journal of Engineering Geology
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• v.21 no.2
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• pp.133-145
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• 2011

Unsaturated soil column tests were performed for weathered gneiss soil and weathered granite soil to assess the relationship between infiltration velocity and rainfall condition for different rainfall durations and for multiple rainfall events separated by dry periods of various lengths (herein, 'rainfall break duration'). The volumetric water content was measured using TDR (Time Domain Reflectometry) sensors at regular time intervals. For the column tests, rainfall intensity was 20 mm/h and we varied the rainfall duration and rainfall break duration. The unit weight of weathered gneiss soil was designed 1.21 $g/cm^3$, which is lower than the in situ unit weight without overflow in the column. The in situ unit weight for weathered granite soil was designed 1.35 $g/cm^3$. The initial infiltration velocity of precipitation for the two weathered soils under total amount of rainfall as much as 200 mm conditions was $2.090{\times}10^{-3}$ to $2.854{\times}10^{-3}$ cm/s and $1.692{\times}10^{-3}$ to $2.012{\times}10^{-3}$ cm/s, respectively. These rates are higher than the repeated-infiltration velocities of precipitation under total amount of rainfall as much as 100 mm conditions ($1.309{\times}10^{-3}$ to $1.871{\times}10^{-3}$ cm/s and $1.175{\times}10^{-3}$ to $1.581{\times}10^{-3}$ cm/s, respectively), because the amount of precipitation under 200 mm conditions is more than that under 100 mm conditions. The repeated-infiltration velocities of weathered gneiss soil and weathered granite soil were $1.309{\times}10^{-3}$ to $2.854{\times}10^{-3}$ cm/s and $1.175{\times}10^{-3}$ to $2.012{\times}10^{-3}$ cm/s, respectively, being higher than the first-infiltration velocities ($1.307{\times}10^{-2}$ to $1.718{\times}10^{-2}$ cm/s and $1.789{\times}10^{-2}$ to $2.070{\times}10^{-2}$ cm/s, respectively). The results reflect the effect of reduced matric suction due to a reduction in the amount of air in the soil.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.1
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• pp.36-42
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• 2007

To compare the survival rate of periodontal ligament cells preserved in storage media with good availability at the time of an avulsion injury, periodontal ligament cells were incubated in ${\alpha}-MEM$ culture medium containing 10% FBS in condition of $37^{\circ}C$, 5% $CO_2$. These cells were then cultured in HBSS, ${\alpha}-MEM$, milk(S co., P. co.) and tap water at the temperature of 4, 25, $37^{\circ}C$ each in 60 min. The groups were measured by MTT assay. The results were as follows : 1. Among the storage media at $4^{\circ}C$, ${\alpha}-MEM$ and P-milk had the highest preserving ability of periodontal ligament cells, while that of HBSS S-milk and tap was low in order. 2. Among the storage media at $25^{\circ}C$, ${\alpha}-MEM$ had the highest preserving ability of periodontal ligament cells, while that of P-milk, HBSS, S-milk, tap water was low in order. 3. Among the storage media at $37^{\circ}C$, the preserving ability of periodontal ligament cells was very high in ${\alpha}-MEM$, P-milk, HBSS and S-milk, it's lowest in tap water. 4. The preserving ability of periodontal ligament cells in ${\alpha}-MEM$ was high at $4^{\circ}C$ and it's low in order of $25^{\circ}C$, $37^{\circ}C$, but in HBSS was high at $4^{\circ}C$ and it's low at $25^{\circ}C$, $37^{\circ}C$ 5. The preserving ability of periodontal ligament cells in S-milk and P-milk was high at $4^{\circ}C$, $25^{\circ}C$ and it s low at $37^{\circ}C$. In conclusion, HBSS is the storage medium of choice in an avulsion, but in this study it is preferable to choose milk at $4^{\circ}C$ for tooth since it is easy to get and affect cell viability.

• Management & Information Systems Review
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• v.37 no.3
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• pp.27-47
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• 2018

In this study, we examine how land use zoning affects the land price controlling other variables such as road-facing condition of the land, land form, land age after its development and land size. We employ geographically weighted regression analysis which reflects spatial dependency as methodology with a data sample of land transaction price data of Jangyu, a new town, in Korea. The results of our empirical analysis show that the respective coefficients of traditional regression and geographically weighted regression are not significantly different. However, after calculating Moran's Index with residuals of both OLS and GWR models, we find that Moran's Index of GWR decreases around 26% compared to that of OLS model, thus improving the problem of spatial autoregression of residuals considerably. Unlike our expectation, though, in both traditional regression and geographically weighted regression where residential exclusive area is used as a reference variable, the dummy variable of the residential land for both housing and shops shows a negative sign. This may be because the residential land for both housing and shops is usually located in the level area while the residential exclusive area is located at the foot of a mountain or on a gentle hill where the residents can have good quality air and scenery. Although the utility of the residential land for both housing and shops is higher than its counterpart's since it has higher floor area ratio, amenity which can be explained as high quality of air and scenery in this study seems to have higher impact in purchase of land for housing. On the other hand, land for neighbourhood living facility seems to be valued higher than any other land zonings used in this research since it has much higher floor area ratio than the two land zonings above and can have a building with up to 5 stories constructed on it. With regard to road-facing condition, land buyers seem to prefer land which faces a medium-width road as expected. Land facing a wide-width road may have some disadvantage in that it can be exposed to noise and exhaust gas from cars and that entrance may not be easy due to the high speed traffic of the road. In contrast, land facing a narrow road can be free of noise or fume from cars and have privacy protected while it has some inconvenience in that entrance may be blocked by cars parked in both sides of the narrow road. Finally, land age variable shows a negative sign, which means that the price of land declines over time. This may be because decline of the land price of Jangyu was bigger than that of other regions in Gimhae where Jangyu, a new town, also belong, during the global financial crisis of 2008.

• The Transactions of the Korea Information Processing Society
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• v.1 no.3
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• pp.367-379
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• 1994

This paper describes scheduling algorithms of the UNIX operating system and shows an analytical approach to approximate the average conditional response time for a process in the UNIX operating system. The average conditional response time is the average time between the submittal of a process requiring a certain amount of the CPU time and the completion of the process. The process scheduling algorithms in thr UNIX system are based on the priority service disciplines. That is, the behavior of a process is governed by the UNIX process schuduling algorithms that (ⅰ) the time-shared computer usage is obtained by allotting each request a quantum until it completes its required CPU time, (ⅱ) the nonpreemptive switching in system mode and the preemptive switching in user mode are applied to determine the quantum, (ⅲ) the first-come-first-serve discipline is applied within the same priority level, and (ⅳ) after completing an allotted quantum the process is placed at the end of either the runnable queue corresponding to its priority or the disk queue where it sleeps. These process scheduling algorithms create the round-robin effect in user mode. Using the round-robin effect and the preemptive switching, we approximate a process delay in user mode. Using the nonpreemptive switching, we approximate a process delay in system mode. We also consider a process delay due to the disk input and output operations. The average conditional response time is then obtained by approximating the total process delay. The results show an excellent response time for the processes requiring system time at the expense of the processes requiring user time.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.126-135
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• 2002

Plate bonding technique has been widely used in strengthening of existing concrete structures, although it has often a serious problem of premature falure such as interface separation and rip-off. However, this premature failure problem has not been well explored yet especially in view of local failure mechanism around the interface of plate ends. The purpose of the present study is, therefore, to identify the local failure of strengthened plates and to derive a separation criterion at the interface of plates. To this end, a comprehensive experimental program has been set up. The double lap pull-out tests considering pure shear force and half beam tests considering combined flexure-shear force were performed. The main experimental parameters include plate thickness, adhesive thickness, and plate end arrangement. The strains along the longitudinal direction of steel plates have been measured and the shear stress were calculated from those measures strains. The effects of plate thickness, bonded length, and plate end treatment have been also clarified from the present test results. Nonlinear finite element analysis has been performed and compared with test results. The Interface properties are also modeled to present the separation failure behavior of strengthened members. The cracking patterns as well as maximum failure loads agree well with test data. The relation between maximum shear and normal stresses at the interface has been derived to propose a separation failure criterion of strengthened members. The present study allows more realistic analysis and design of externally strengthened flexural member with steel plates.

• Journal of Chest Surgery
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• v.32 no.3
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• pp.281-286
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• 1999

Background: The purpose of this study is to analyze the types of complications, the incidences of complications, and preoperative and postoperative risk factors affecting the incidence of the complication. Material and Method: Between August 1990 and August 1997 in Asan Medical Center, 42 patients(24 men and 18 women) underwent surgical resection for pulmonary aspergilloma. The mean age was 46.6${\pm}$11.5 years(range 29 to 69 years). Hemoptysis(90%) was the most common presentation. Pulmonary tuberculosis was the most common predisposing cause(81%). The associated diseases were bronchiectasis(n=11), active puolmonary tuberculosis(n=9), diabetes mellitus(n=8), lung carcinoid(n=1), and acute myeloblastic leukemia(n=1). Lobectomy was done in 32 cases(76%), segmentectomy or wedge resection in 4, pneumonectomy in 2, and lobectomy combined with segmentectomy in 4. Result: Operative mortality was 2%. The most common postoperative complication was persistent air leakage(n=6). The variables such as age, sex, pulmonary function test, amount and duration of hemoptysis, associated diseases(diabetes mellitus, active pulmonary tuberculosis), mode of preoperative management(steroid, antifungal agent, bronchial arterial embolization), and modes of operative procedures were statistically insignificant. The radiologic extent of infiltration to normal lung parenchyme was statistically significant(p=0.04). Conclusion: We conclude that the extent of the infiltration to normal lung parenchyme in preoperative radiologic studies should be carefully evaluated to reduce the postoperative complications in surgery for pulmonary aspergilloma.