• Corrosion Science and Technology
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• 제14권2호
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• pp.47-53
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• 2015

Recently, the bending process is greatly applied to fabricate the pipe line. Bending process can reduce welding joints and then decrease the number of inspection. Thus, the maintenance cost will be reduced. Induction heat bending process is composed of bending deformation by repeated local heat and cooling. By this thermal process, corrosion properties and microstructure can be affected. This work focused on the effect of induction heating bending process on the properties of ASME SA106 Gr. C low carbon steel pipes. Microstructure analysis, hardness measurements, and immersion corrosion test were performed for base metal and bended area including extrados, intrados, crown up, and down parts. Microstructure was analyzed using an optical microscope and SEM. Hardness was measured using a Rockwell B scale. Induction heat bending process has influenced upon the size and distribution of ferrite and pearlite phases which were transformed into finer structure than those of base metal. Even though the fine microstructure, every bent area showed a little lower hardness than that of base metal. It is considered that softening by the bending process may be arisen. Except of I2, intrados area, the others showed a similar corrosion rate to that of base metal. But even relatively high rate of intrados area was very low and acceptable. Therefore, it is judged that induction heat bending process didn't affect boric acid corrosion behaviour of carbon steel.

• 한국농공학회논문집
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• 제58권3호
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• pp.29-38
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• 2016

There have been only a few studies focused on the stabilization of metal (loid)s in anaerobic soils such as paddy soils. In this study, laboratory-scale column tests were conducted to artificially manipulate anoxic conditions in submerged paddy fields and we observed the release behavior of As, Cd, Pb, and Zn, as well as to examine the stabilization effect of steel refining slag (SRS) on the metal(loid)s. The leachate samples were collected and chemical parameters were monitored during the test period. Results suggest that anoxic conditions were developed during submersion, and that As or heavy metals (particularly Cd) fractions bound to ferrous (Fe) /manganese (Mn) oxides were easily dissociated. Moreover, As is also reduced by itself to a trivalent form with higher mobility in the reducing environment of rice paddy soil. However, it was also shown that SRS significantly decreased the dissolution of Zn, Pb, Cd, and As in the the leachates; their removal rates in the SRS-treated soil were 66 %, 45 %, 24 %, and 84 %, respectively, of those in the control soil.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권6호
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• pp.102-111
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• 2012

Fine suspended solids generated effluence from treatment process of mine drainage could destroy environment as the aesthetic landscapes, and depreciate water quality. Therefore, the purpose of this research is focused on process development applied the actual field for controlling fine suspended solids and heavy metals, and so lab-scale test was performed for inducement of basic data. The mine drainage used in this research was sampled in H mine located Jeongseon-gun, Gangwon-do. Concentration of suspended solid, arsenic, iron and manganese was exceeded the standard of contaminant limitation for the clean water, and particle size of suspended solid was less than 10 m as fine particle. Although hydraulic retention time of mine drainage for effective settling was required more than 6 hours, hydraulic retention time would be increased in winter season when the settling efficiency could be reduced because of viscosity decreasing. Moreover, installed inclination plate helped to increase settling efficiency of suspended solid about 48 %. Filtering media that was the most effective removal of suspended solids and heavy metal was decided granular activated carbon of 1~2 mm was the optimal size.

• Journal of Yeungnam Medical Science
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• 제37권4호
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• pp.349-355
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• 2020

Active and prompt scale-up screening tests are essential to efficiently control the coronavirus disease 2019 (COVID-19) outbreak. The goal of this work was to identify shortcomings in the conventional screening system (CSS) implemented in the beginning of the outbreak. To overcome these shortcomings, we then introduced a novel, independently developed system called the Yeungnam University type drive-through (YU-Thru), and distributed it nationwide in Korea. This system is similar to the drive-throughs utilized by fast food restaurants. YU-Thru system has shortened the time taken to test a single person to 2-4 minutes, by completely eliminating the time required to clean and ventilate the specimen collection room. This time requirement was a major drawback of the CSS. YU-Thru system also reduced the risk of subjects and medical staff infecting one another by using a separate and closed examination system. On average, 50 to 60 tests were conducted per day when using the CSS, while now up to 350 tests per day are conducted with the YU-Thru system. We believe that the YU-Thru system has made an important contribution to the rapid detection of COVID-19 in Daegu, South Korea. Here, we will describe the YU-Thru system in detail so that other countries experiencing COVID-19 outbreaks can take advantage of this system.

• The Journal of Korean Physical Therapy
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• 제29권4호
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• pp.158-163
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• 2017

Purpose: The purpose of this study was to investigate the relationship among pain, range of motion of the neck, neck disability index and grip strength after thoracic manipulation and cervical stabilization training in patients with chronic neck pain. Methods: In this study, twelve subjects with chronic neck pain were included. All participants had thoracic manipulation and cervical stabilization training. Intervention was conducted three times per a week, for 4 weeks. The visual analogue scale (VAS), range of motion of neck, neck disability index (NDI), as well as the grip strength before and after intervention were measured in all participants. Paired t-test was used to compare variables before and after intervention. Pearson correlation analysis was used to identify the correlations between the variables. Results: All variables after the intervention were significantly improved. There was a significant negative correlation between VAS and flexion angle of the neck (r=-0.669, p<0.05). Moreover, there was a significant positive correlation between NDI and VAS (r=0.636, p<0.05), and a significant negative correlation between NDI and flexion angle of the neck (r=-0.692, p<0.05). Conclusion: Patients with reduced pain following therapeutic intervention illustrated that there would be an improvement in the flexion angle rather than the extension angle of the neck, and that those with increased flexion angle would have less restriction of activities in daily living.

• 한국지반신소재학회논문집
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• 제16권4호
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• pp.177-190
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• 2017

본 연구에서는 운영 중인 교량하부에 근접 시공되는 지하철 터널의 형식에 대한 비교분석 내용을 다루었다. 이를 위해 먼저 실제현장에 대해 상사비를 적용하여 각각의 터널 형식에 대한 터널 구조물 및 교량에 대해 축소 모형을 제작하고 시공과정을 모사하는 실험을 수행하였다. 실험결과는 사진 이미지 분석법인 PIV 기법과 LVDT에 의한 지반 거동 및 터널구조물의 변형률 등을 이용한 분석을 통해 각각의 터널 구조물 시공이 교량 말뚝 및 터널 주변 지반의 거동에 미치는 영향을 고찰하였다. 실험결과 파이프 추진 공법이 2-Arch 터널 시공법에 비해 주변지반에 미치는 영향 및 교량의 침하에 미치는 영향을 최소화할 수 있는 것으로 검토되었다. 아울러 PIV 기법은 터널시공 모사 실험과 같이 시공과정이 주변지반의 거동에 절대적인 영향을 미치는 조건에 대한 실험결과 분석에 매우 유용하게 적용될 수 있는 것으로 검토되었다.

• 대한지하수환경학회지
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• 제4권3호
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• pp.116-121
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• 1997

정화 효율과 운영상의 문제점을 파악하였다. 반응조 유입수 및 방류수에 대하여 현장에서 pH 및 Eh(산화환원전위)를 측정하였고 Cd, Pb, As, Zn, Cu, Fe, Al 및 Mn 등을 실험실에서 분석 하였다. 반응조 방류수에 대한 수질분석 결과 우분 및 석회석이 섞인 볏짚 반응조의 Cu, Zn, Fe, Cd, Al, Mn및 Pb의 정화효율(최대)은 98%, 100%, 99%, 100%, 97%, 61% 및 100%였고 이때 반응조의 수질환경은 pH 6 그리고 Eh 값이 -300 mV부근의 환원환경이었다. 그러나 시간이 경과함에 따라 Eh 값은 상승하였고 Al을 제외한 금속성분의 정화효율도 낮아져 반응조의 혐기환경유지는 금속성분의 정화에 매우 중요하였다. 반응조 시설을 운영한 결과 배관내의 산화물 Scale 및 기질물질의 부피 변화는 광산배수의 흐름을 방해하는 요소로 나타났다.

• 상하수도학회지
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• 제19권1호
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• pp.68-77
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• 2005

This study was performed to evaluate the application of corrosion inhibitor and to examine the correlation between corrosion rate and red water in a series of batch tests and a test using auto corrosion monitoring system at A water treatment plant in Gyeonggido. The corrosion study in the auto corrosion monitoring system indicated that Fe concentration decreased by 30~50% and corrosion rate also reduced remarkably with corrosion inhibitor at $1.8mg\;PO_4/L$. After addition of corrosion inhibitor, it was indicated the effective adsorption of the inhibitor on the surface of the pipe line forming a protective film. The corrosion rate increases with the increase in Fe concentration. With $1.8mg\;PO_4/L$ of corrosion inhibitor, the corrosion rate decreased remarkably. Fe concentration had correlation to not only red water problems but also the corrosion rate that actually dissolved into the water, primarily due to the deposition of oxidized iron or other compounds as a scale, which serves as a large reservoir of corrosion by-product. Therefore, corrosion rate can be estimated by Fe concentration. For these reasons, an effective corrosion inhibitor is also an effective red water control reagent. The effect of the corrosion inhibition can last for some time even the application the corrosion inhibitor is discontinued. For the cost effective and efficient corrosion control, the concentration and timing of corrosion inhibitor addition must be determined properly.

• Journal of Acupuncture Research
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• 제28권2호
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• pp.165-172
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• 2011

Objectives : The objective of this case report was to observe the effect of musculoskeletal ultrasound-guided acupotomy therapy on posterior headache caused by traffic accident. Methods : Musculoskeletal ultrasound-guided acupotomy therapy was performed to two patients whose brain MRI or CT results were normal, but posterior headache did not improve with general eastern medical treatment. Results : One patient's VAS(visual analogue scale) of posterior headache was decreased for the first time after ultrasound-guided acupotomy therapy, and steadily reduced. The other patient's VAS was also decreased for the first time after musculoskeletal ultrasound-guided acupotomy therapy. Two patient's Korean HIT-6(Korean headache impact test-6) scores were decreased after one month. Conclusions : If general eastern medical treatment had little effect on traffic accident induced posterior headache, musculoskeletal ultrasound-guided acupotomy therapy can be applied.

• 한국환경보건학회지
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• 제35권5호
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• pp.411-416
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• 2009

This study was initiated to improve the cooling water quality by chemical coagulation and sedimentation in steel mills. Due to the inefficient flocculation in the settling tanks of blast furnace cooling water systems, the solid particles in the cooling water overflow accumulate and clog the cooling system. To protect the cooling water system from such fouling, proper flocculants must be continuously used. Laboratory tests were performed for the indirect cooling water system of a plate mill. The batch test in the gas scrubbing cooling water system of a blast furnace showed that the proposed coagulant was more effective for the improvement of coagulation and sedimentation than the existing one. During the tests, cationic flocculants were more effective than use of only an anionic flocculant. The suggested combination of anionic and cationic flocculants can probably improve the turbidity removal efficiency of the cooling water. Proper control of the overflow rate by the designed residence time would help turbidity removal efficiency in the settling tank. In addition, the settling can be enhanced by adopting rapid and slow mixing alternatively. Scale problems in blast furnace cooling water system were reduced to some extent by efficient settling.