• 한국자동차공학회논문집
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• 제16권1호
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• pp.114-120
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• 2008

Recently, the nano-PM's number concentration emitted by diesel internal combustion engine has focused on attention because this particulate matters are suspected being hazardous of human health. In this study, The nano-PM mass and size of diesel passenger vehicles were measured on chassis dynamometer test bench. The particulate matters(PM) emissions of these vehicles were investigated by number concentration too. A condensation particle counter(CPC) system was applied to measure the particle number and size concentration of diesel exhaust particles at the end of dilution tunnel along the NEDC(ECE15+EUDC) and CVS-75 vehicle test mode. As the research result, the characteristic of vehicle test mode on the diesel nano-particle number and size distribution was investigated in this study.

• 한국수소및신에너지학회논문집
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• 제23권1호
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• pp.65-72
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• 2012

Rankine cycle using ammonia-water mixture as a working fluid has attracted much attention, since it may be a very useful device to extract power from low-temperature heat source. In this work, the thermodynamic performance of regenerative ammonia-water Rankine cycle is thoroughly investigated based on the second law of thermodynamics and exergy analysis, when the energy source is low-temperature heat source in the form of sensible energy. In analyzing the power cycle, several key system parameters such as ammonia mass concentration in the mixture and turbine inlet pressure are studied to examine their effects on the system performance including exergy destructions or anergies of system components, efficiencies based on the first and second laws of thermodynamics. The results show that as the ammonia concentration increases, exergy exhaust increases but exergy destruction at the heat exchanger increases. The second-law efficiency has an optimum value with respect to the ammonia concentration.

• 대한간호학회지
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• 제16권3호
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• pp.78-96
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• 1986

The sympathico-adrenergic system and the hypophyseal-adrenocortical system mediates the regulation of the internal milieu. And the kidneys regulate both water and electrolyte balance of the body fluid. The kidneys are the sites of production of renin which participate indirectly in maintaining renin. angiotensin-aldosterone system. These system de-serve special attention in the context of adjustment the effects on the body function. And so, maximal exercise and work load are associated with home-osthetic function. The nurses working in the hospital have been complained of fatigue and stress by frequent duty changes and overload. In order to define this, the possible changes of hormonal excretion during three-shift nursing practice were investigated. Urine samples were collected at pre-duty and post-duty, and were measured with chemical assay and radioimmunoassay in 30 nursing students, in nursing practice and 43 nursing students, in studying. The results obtained were as follows. 1. In nursing practice, urinary norepinephrine concentration showed a marked increase during day duty, urinary cortisol concentration showed a marked increase during evening duty, and urinary renin concentration was increased in night duty, 2. Corrected ratio of urinary sodium excreted by the urinary excretion of creatinin (UNa/UCr) and UCl/UCr showed a marked decrease during night duty. Nursing practice did not affect on the UK/UCr and urinary concentrating ability. From these results, it is suggested that further studies the define the effects on some physiological function of the three-shift nursing practice against circadian rhythm are needed for better working condition of nurses.

• Environmental Engineering Research
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• 제24권3호
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• pp.382-388
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• 2019

Although nanobubbles attract significant attention, their characteristics and applications have not been thoroughly defined. There are diverse opinions about the definition of nanobubbles and controversy regarding methods that verify their characteristics. This study defines nanobubbles as having a size less than $1{\mu}m$. The generation of these sub-micron (nano) bubbles may be verified by induced coalescence or light scattering. The size of a sub-micron (nano) bubbles may be measured by optical, and confocal laser scanning microscopy. Also, the size may be estimated by the relationship of bubble size with the dissolved oxygen concentration. However, further research is required to accurately define the average bubble size. The zeta potential of sub-micron (nano) bubbles decreases as pH increases, and this trend is consistent for micron bubbles. When the bubble size is reduced to about 700-900 nm, they become stationary in water and lose buoyancy. This characteristic means that measuring the concentration of sub-micron (nano) bubbles by volume may be possible by irradiating them with ultrasonic waves, causing them to merge into micron bubbles. As mass transfer is a function of surface area and rising velocity, this strongly indicates that the application of sub-micron (nano) bubbles may significantly increase mass transfer rates in advanced oxidation and aeration processes.

• 멤브레인
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• 제30권6호
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• pp.373-384
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• 2020

바이오의약품 중에서도 항체의약품의 수요가 증가함에 따라 항체를 상업용으로 개발하기 위한 연구가 활발히 진행되고 있다. 항체의약품의 제조공정 중 downstream 공정은 의약품 성능에 직접적으로 영향을 미치기 때문에 중요하게 다뤄지며, 본 총설은 그 중에서도 농축 및 제제화를 목적으로 행해지는 한외여과 및 정용여과 공정에서 사용되는 한외여과막의 주요 제품 및 공정 특성을 살펴보고, 최근 연구 동향에 대해 소개하고자 한다.

• Physical Therapy Rehabilitation Science
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• 제5권4호
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• pp.193-197
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• 2016

Objective: In the present study, the effects of visual restriction and unstable base dual-task training (VUDT), stable base dual-task training (SDT), and on stroke patients' balance and concentration abilities were examined. Design: Two-group pretest-posttest design. Methods: Dual-task training was conducted for thirty persons with chronic stroke who were hospitalized or receiving physical therapy and were randomly assigned to either the VUDT group (n=15) or the SDT group (n=15). The subjects were divided into two groups of 15 participants each, the VUDT group and the SDT group. Dual-task training was administered for 30 minutes per session, three times a week for 8 weeks. The participants' balance was measured via the center of pressure migration distances, functional reach test (FRT), Berg Balance Scale (BBS), and attention was measured using the trail-making test and the Stroop test. Results: In comparisons within each group, the two groups showed significant differences before and after the training (p<0.05). In the comparisons between the groups, the VUDT group showed significant improvements in center of pressure (COP), FRT, and BBS, and TMT compared to the SDT group (p<0.05). Conclusions: It would be more effective to conduct dual-task training as a rehabilitation training program under vision restriction and unstable supporting surface conditions than to conduct the test under unstable supporting plane conditions to improve balance and attention in chronic stroke patients.

• 한국방사선학회논문지
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• 제10권3호
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• pp.171-180
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• 2016

본 연구는 고 에너지 방사선 조사에 기인된 방사선치료실 내 오존 농도의 변화를 비교 분석하고자 하였다. 이를 위하여 치료실 주변 대기 중 오존 농도와 치료실 내 배경 오존 농도를 분석하여 고 에너지 방사선 조사에 기인된 치료실 내 평균 오존 농도를 비교하였다. 치료실 내 배경 오존 농도는 평균 $17.4{\pm}7.9ppb$로 방사선치료실 주변의 대기 중 오존 농도(평균 $36.8{\pm}22.3ppb$)보다 약 50% 정도 통계적으로 유의하게 낮게 나타났다(p<0.05). 고 에너지 방사선 조사에 기인된 치료실 내 오존 농도는 방사선이 조사됨과 동시에 배경 오존 농도의 약 2배 수준으로 급격하게 증가되었으며 조사시간이 증가함에 따라 기울기가 일정한 증가 추이를 보이다가 약 130초에서 180초 부근에서 최대 오존 농도를 이루고 점차 포화되는 경향을 보였으며 배경 오존 농도로 감소하는데 소요되는 시간은 약 10분 이상이었다. 본 연구 결과를 토대로 고 에너지 방사선 조사에 기인된 방사선치료실 내 오존 농도는 후각을 자극하는 오존의 특이한 냄새를 맡거나 순간적인 호흡 곤란과 마른기침으로 가슴 통증 등의 신체적 증상이 나타날 수 있는 수준으로 밀폐된 방사선치료실에서 고농도 오존에 장시간 노출될 경우 폐 질환을 악화시킬 수 있기 때문에 각별한 주의가 요구된다.

• 한국실내디자인학회논문집
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• 제21권4호
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• pp.87-95
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• 2012

This study is for the analysis to which element of space the users observing the lobby at a public space pay more attention for their visual perception. It is focused on the typology process of observation characters. The subjects, in the observation process, came to be interested in the circumstantial clues for space perception and the detailed characters drawing their interest. I could analyze the observation characters of the subjects observing the space by the comprehension and typology of their observation characters. First, from the viewpoint of successive 9 times of observations, each subject observed for 0.32 second to get the visual perception in the applied space, but spent another 0.39 second for the exploration of another observation object or the space roaming. The observation character of the subjects at the lobby of the public space selected for this experiment was that they spent more time on space exploration than on concentration on a point in the space. Second, I analyzed the typology process through the time range. Since the subjects' frequency varied depending on the way to set up the time range, the necessity was proposed that the time range for the analysis of observation characters should be set up more objectively. Third, in case of analyzing the observation characters by 10-second-unit time range, the concentration in the beginning and the middle was 25%, and that in the beginning and the final 41.7%, which showed that 75% of the subjects concentrated in the beginning of the observation time when the concentration in the beginning is added to it. Fourth, the type 3 categorized as "concentration in the beginning and the middle" is the group 47.1 percent of the subjects belong to, and each subject concentrated 1.1 times in the beginning and 2.1 times in the final, which showed that the concentration in the final was 1.75 times as high as that in the beginning.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.148.2-148.2
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• 2013

We prepared hydrophobic PDMS-coated porous silica as pre-concentration adsorbent for chemical warfare agents (CWAs). Since CWAs can be harmful to human even with a small amount, detecting low-concentration CWAs has been attracting attention in defense development. Porous silica is one of the promising candidates for CWAs pre-concentration adsorbent since it is thermally stable and its surface area is sufficiently high. A drawback of silica is that adsorption of CWAs can be significantly reduced due to competitive adsorption with water molecule in air since silica is quite hydrophilic. In order to solve this problem, hydrophobic polydimethylsiloxane (PDMS) thin film was deposited on silica. Adsorption and desorption of chemical warfare agent (CWA) simulants (Dimethylmethylphosphonate, DMMP and Dipropylene Glycol Methyl Ether, DPGEM) on bare and PDMS-coated silica were studied using temperature programed desorption (TPD) with and without co-exposing of water vapor. Without exposure of water vapor, desorbed amount of DMMP from PDMS-coated silica was twice larger than that from bare silica. When the samples were exposed to DMMP and water vapor at the same time, no DMMP was desorbed from bare silica due to competitive adsorption with water. On the other hand, desorbed DMMP was detected from PDMS-coated silica with reduced amount compared to that from the sample without water vapor exposure. Adsorption and desorption of DPGME with and without water vapor exposing was also investigated. In case of bare silica, all the adsorbed DPGME was decomposed during the heating process whereas molecular DPGME was observed on PDMS-coated silica. In summary, we showed that hydrophobic PDMS-coating can enhance the adsorption selectivity toward DMMP under humid condition and PDMS-coating also can have positive effect on molecular desorption of DPGME. Therefore we propose PDMS-coated silica could be an adequate adsorbent for CWAs pre-concentration under practical condition.

• 상하수도학회지
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• 제33권2호
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• pp.95-101
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• 2019

High voltage impulse(HVI) has been gained attention as an alternate technique controlling $CaCO_3$ scale formation. Investigation of key operational parameters for HVI is important, however, those had not been reported yet. In this study, the effect of temperature and applied voltage of HVI on $Ca^{2+}$ concentration was studied. As the applied voltage from 0 to 15kV and the temperature increased from 20 to $60^{\circ}C$, the $Ca^{2+}$ concentration decreased, indicating that the aqueous $Ca^{2+}$ precipitated to $CaCO_3$. The $Ca^{2+}$ concentration decreased up to 81% under the condition of 15kV and $60^{\circ}C$. Rate constant for the precipitation reaction, k was determined under different temper1ature and voltage. The reaction rate constant under the 15kV and $60^{\circ}C$ condition was evaluated to $66{\times}10^{-3}L/(mmol{\cdot}hr)$, which was 5 times greater than the k of the reaction without HVI at same temperature. The increases in k by HVI at higher temperature region(40 to $60^{\circ}C$) was much greater than at lower temperature region(20 to $40^{\circ}C$), which implies temperature is more important parameter than voltage for reducing $Ca^{2+}$ concentration at high temperature region. These results show that the HVI induction accelerates the precipitation to $CaCO_3$, particularly much faster at higher temperature.