• Corrosion Science and Technology
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• 제7권5호
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• pp.283-287
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• 2008

The drag reduction agency (DRA) for gas pipeline, a novel method used for reducing friction or drag on a gas flowing to increase the transmission efficiency of gas pipeline, is a more flexible and economical technology than internal flow efficient coatings. In this paper, an effective DRA has been developed in Authors' Institute by analyzing the hydrodynamic friction resistance on internal gas pipeline and then studying the work mechanism and molecular structure of DRA. In the meantime, a group of property test for selecting DRA material has been determined, including viscosity, contact angle, volatility, corrosion, slab extending, and flow behavior in horizontal tube. The inhibition efficiency and drag reduction efficiency of the developed DRA have been investigated finally based on the relevant test methods. Results of corrosion test show that the developed DRA has very good inhibition effect on mild steel by brushing a thin layer of DRA on steel specimens, giving inhibition efficiency of 91.2% and 73.1% in 3%NaCl solution and standard salt fog environment respectively. Results of drag-reducing test also show that the Colebrook formula could be used to calculate friction factors on internal pipes with DRA as the Reynolds number is in the range of $0.75\times10^5\sim2.0\times10^5$. By comparing with normal industrial pipes, the friction resistance coefficient of the steel pipe with DRA on internal wall decreases by 13% and the gas flux increases by 7.3% in testing condition with Reynolds number of $2.0\times10^5$.

• Restorative Dentistry and Endodontics
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• 제16권1호
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• pp.41-59
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• 1991

This study was performed to elucidate the distribution and correlation of immunoglobulin G subclasses with the degree of inflammation in the experimentally induced rat pulp and periapical pathoses. The pulp exposures were made in 108 mandibular 1st molars of 54 rats and the teeth were left open to the oral environment The animals were sacrified at 3, 7, 15, 30, 60 and 90 days after pulp exposure, and examined microscopically and radiographically Seventy one specimens were routinely sectioned at the thickness of 4 - $6{\mu}$ and stained with Hematoxylin - eosin for histologic examination, with toluidine blue for mast cells, and with the primary antibodies against rat IgG subclasses by using the Avidin - Biotin complex method. The following results were obtained: 1. As the degree of inflammation of rat pulp and periapeces intensified, the number of IgG subclass containing cells per unit area, especially IgG2a and IgG2c, decresased. 2. The IgG2c cells were most predominantly found in the lesions with slight inflammation, IgG1 cells in mild or severe inflammation, and IgG2a cells in moderate inflammation. 3. IgG subclass containg cells were more predominantly observed in the periapical granuloma than periapical abscess or cyst(p<0.01). 4. IgG2a containing cells were predominant in pulp inflammation, IgG1 containing cells in periapical granuloma, IgG2a cells and IgG1 cells in periapical abscess, and IgG2a cells were significantly predominant in periapical cyst. 5. The number of IgG subclass containing cells and mast cells in periapical tissue decreased with time lapse after pulp exposure. And correlation index between mast cells and IgG1, IgG2a, IgG2b was stastically high.

• 한국동물위생학회지
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• 제33권2호
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• pp.97-103
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• 2010

Foot-and-mouth disease (FMD) commonly infects cloven-hoofed livestock animals such as cattle, pig, sheep, and goat and its clinical signs are well-known. Besides livestock, FMD can be transmitted among cloven-hoofed animals in the wild. FMD mostly affects livestock animals in farms, but, wild animals are likely to play a pivotal role in spreading the disease due to their way of free living. In the case of deer, the clinical signs of FMD vary widely from subclinical to severe infections. Thus, in some deer species, it may be hard to verify clinical signs of FMD. A deer may carry the virus up to 11 weeks after exposure, shedding the virus during the period. However, deer is not considered as a typical host for persistent infection like buffalo, cattle or sheep. In Korea, small-scale livestock farms which have less than 10 animals make up 63.6% of the entire livestock farms. Considering raising environment in deer farms, it is assumed that the risk of virus excretion and consequent transmission of FMD among deers is relatively lower than other cloven-hoofed animals. However, Sika deer and Elk which are typical deer species in Korea would manifest mild to subclinical symptoms upon FMD infection. Therefore, laboratory testing is necessary to confirm FMD in these animals because of difficulty in verifying clinical signs and the risk of virus shedding during inapparent infection.

• Corrosion Science and Technology
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• 제7권6호
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• pp.315-318
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• 2008

The atmospheric corrosion performance of Al-alloying, Si-alloying and Al-Si-alloying steel were studied by wet/dry cyclic corrosion tests (CCT) at $30^{\circ}C$ and 60% relative humidity (RH). The corrosion electrolyte used for CCT was 0.052 wt% $NaHSO_{3}$ (pH~4) solution. The result of gravimetry demonstrated that Al-Si-bearing steels showed lower corrosion resistance than other rusted steels. But the rusted 0.7%Si-alloying steel showed a better corrosion resistance than rusted mild steel. Polarization curves demonstrated that Al-/Si-alloying and Al-Si-alloying improved the rest potential of steel at the initial stage; and accelerated the cathodic reduction and anodic dissolution after a rust layer formed on the surfaces of steels. XRD results showed that Al-Si-alloying decreased the volume fraction of $Fe_{3}O_{4}$ and $\alpha-FeOOH$. The recycle of acid accelerated the corrosion of steel at the initial stage. After the rust layer formed on the steel, the leak of rust destabilized the rust layer due to the dissolution of compound containing Al (such as $FeAl_{2}O_{4}$, $(Fe,\;Si)_{2}(Fe,\;Al)O_{4}$). Al-Si-alloying is hence not suitable for improving the anti-corrosion resistance of steel in industrial atmosphere.

• 대한기계학회논문집B
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• 제36권1호
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• pp.75-81
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• 2012

고온의 동축류 공기와 수소가 함유된 메탄 연료제트에서 자발화된 층류 부상화염의 특성을 실험적으로 조사하였다. 그 결과로 순수 메탄 제트에서 자발화되는 경계 온도인 920 K 를 초과하는 초기 온도에서 메탄/수소 혼합기의 자발화된 부상화염은 연료 몰분율에 따라 삼지화염 또는 마일드 연소를 보였고, 제트속도에 따라 부상화염의 높이가 증가하는 전형적인 특성을 보였다. 소량의 수소가 첨가된 부상화염의 높이는 메탄의 경우와 유사하게 단열적 점화지연시간의 2 승에 대한 의존성이 유지되었다. 반면에, 초기 온도가 920 K 미만인 경우에서 화염은 수소의 점화 촉진에 의해서 자발화 되었다. 그리고 제트속도가 증가함에 따라 자발화된 부상화염의 높이는 비선형적으로 감소하는 독특한 특성을 보였으며, 수소의 선호확산이 그 현상에 대해서 중요한 역할을 할 것으로 예상된다.

• Corrosion Science and Technology
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• 제9권6호
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• pp.310-316
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• 2010

Recently a fuel oil of the diesel engine of the marine ship is being changed with heavy oil of low quality as the oil price is higher more and more. Therefore the wear and corrosion in all parts of the engine such as cylinder liner, piston crown, spindle and seat ring of exhaust valves are predominantly increased. In particular the degree of wear and corrosion of piston crown is more seriously compared to the other parts of the engine due to operating in severe environment such as the high temperature of exhaust gas and repeating impact. Thus the repair weldment of the piston crown is a unique method to prolong the its life in a economical point of view. In this case, filler metals having a high corrosion and wear resistance such as stellite 6, Inconel 625 and Inconel 718 are mainly being used for repair welding. However it has been often happened that piston crown on the ship,s job site is being actually inevitably welded with mild filler metals. Therefore in this study, filler metals such as E4301, E4313 and E4316 were welded at SS401 steel as the base metal, and corrosion property of their weld metals in the case of post weld heat treatment or not was investigated with some electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram and polarization resistance etc. in 0.1% $H_2SO_4$ solution. Corrosion resistance of the weld metal of E4301 was better than the other weld metals in the case of no heat treatment, however, its resistance was considerably decreased with post weld heat treatment(annealing:$625^{\circ}C$, 2 hr) compared to other weld metals. The weld metals of E4313 and E4316 showed a relatively good corrosion resistance by post weld heat treatment.

• 한국실내디자인학회논문집
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• 제16권6호
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• pp.250-257
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• 2007

Characteristics of color application indicated from Kirchsteigfeld is presented the various points of view to be preserved urban housing color. It had been handled as environmental color by view point of community and connectivity rather than color scheme of single housing. First, color to be consisted of basis for urban entirely as background color in urban housing complex has been indicated the bright and cheerful feelings and expressed to be introduced mostly from the single color system. Second, characteristics to be inhibited strongly from housing complex had been indicated by restricted four types of color, formulated the overall context and change through accent and the change from disposition of principal and the accessary of color scheme. In this case, it was not regular formulation, but as a whole category view, it could be provided by orderly regularity system strictly Particularly it had been applied as a whole for lightness change by single color, introduced the different color of building to be centered or remained by a visual point. This had been formed to introduction of color by stand points of housing group not introduction to color by sole concept of building. Third, emphasizing of morphologic feeling by using of difference of lightness, it could be indicated the mild and comfortable stereo-type sensibility from the overall types of housing, we could understand for formation of color code by lightness of slightly differences. Fourth, it had been taken the convenient adaptation method for maintenance of simple graphic system as a environmental color. It has considerable advantage for sustainability of color to indicate on finishing material, form and detail in architecture, as the sole separated color not to be complicated when to be painted over and again or managed continuously.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 1999년도 추계학술대회 논문집
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• pp.216-221
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• 1999

A mental task combined with noise background is an effective model of laboratory stress for study of psychophysiology of the autonomic nervous system (ANS). The intensity of the background noise significantly affects both a subjective evaluation of experienced stress level during test and the physiological responses associated with mental load in noisy environments. Providing tests of similar difficulties we manipulated the background noise intensity as a main factor influencing a psychophysiological outcome and the analyzed reactivity along withe the noise intensity dimension. The goal of this study was to identify the patterns of ANS responses and the relevant subjective stress scores during performance of word recognition tasks on the background of white noise (WN) of the different intensities (55, 70 and 85 dB). Subjects were 27 college students (19-24 years old). BIOPAC, Grass Neurodata System and AcqKnowlwdge 3.5 software were used to record ECG, PPG, SCL, skin temperature, and respiration. Experimental manipulations were effective in producing subjective and physiological responses usually associated with stress. The results suggested that the following potential autonomic mechanisms might be involved in the mediation of the observed physiological responses: A sympathetic activation with parasympathetic withdrawal during mild 55 and 70dB noise (featured by similar profiles) and simultaneous activation of sympathetic and parasympathetic systems during intense 85dB WN. The parasympathetic activation in this case might be a compensatory effect directed to prevent sympathetic domination and to maintain optimal arousal state for the successful performance on mental stress task. It should be mentioned that obtained results partially support Gellhorn's (1960; 1970) "tuning phenomenon" as a possible mechanism underlying stress response.

• Archives of Plastic Surgery
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• 제45권1호
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• pp.69-73
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• 2018

Background Temporal hollowing is inevitable after decompressive craniectomy. This complication affects self-perception and quality of life, and various techniques and materials have therefore been used to restore patients' confidence. Autologous fat grafting in postoperative scar tissue has been considered challenging because of the hostile tissue environment. However, in this study, we demonstrate that autologous fat grafting can be a simple and safe treatment of choice, even for postoperative depressed temporal scar tissue. Methods Autologous fat grafting was performed in 13 patients from 2011 to 2016. Fat was harvested according to Coleman's strategy, using a tumescent technique. Patient-reported outcomes were collected preoperatively and at 1-month and 1-year follow-ups. Photographs were taken at each visit. Results The thighs were the donor site in all cases for the first procedure. The median final volume of harvested fat was 29.4 mL (interquartile range [IQR], 24.0-32.8 mL). The median final volume of fat transferred into the temporal area was 4.9 mL on the right side (IQR, 2.5-7.1 mL) and 4.6 mL on the left side (IQR, 3.7-5.9 mL). There were no major complications. The patient-reported outcomes showed significantly improved self-perceptions at 1 month and at 1 year. Conclusions Despite concerns about the survival of grafted fat in scar tissue, we advise autologous fat grafting for patients with temporal hollowing resulting from a previous craniectomy.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제27권4호
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• pp.41-50
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• 2021

Purpose: This study is aimed at the case of the cognitive health design pilot projects promoted by the Seoul Metropolitan Government since 2014 in terms of design to solve social problems in accordance with the aging population of our society. The purpose of this study is to analyze the maintenance and management of the projects and to suggest implications for the promotion and expansion of sustainable cognitive health design in the future. Method: It set the analysis frame by dividing management into maintenance-damage-demolition for the spatial types and spatial elements suggested in the Seoul Cognitive Health Guidelines. And it analyze the actual conditions of four pilot projects based on the field survey. Results: First, the ratio of damage and demolition was higher than maintenance. Second, designs and techniques with low durability were applied. Most of the cases where floor marks were applied to the external environment were lost or difficult to recognize, and their functions were limited due to storage of goods and parking of vehicles and motorcycles. Third, there was a large variation according to the type of residence. The project contents that can be applied to the low-rise residential area were also limited, and more elements were demolished than in the apartment type. Implications: First, it should limit project contents of space types and space elements that can be maintained even over time. Second, it should seek sustainable design and technical solutions. Third, it should seek alternatives to cognitive health design in low-rise residential areas where a large number of elderly people live.