• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.433-433
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• 2016

Carbon nanotubes (CNT) emitter has widely become an attractive mechanism that draws growing interests for cold cathode field emission. CNT yarns have demonstrated its potential as excellent field emitters. It was demonstrated that a small focal spot size was achieved by manipulating some electrical parameters, such as applied bias voltage at the mesh gate, and electrostatic focal lenses, geometrical parameters, such as axial distances of the anode, and the electrostatic focal lens from the cathode assembly, and the dimension of the opening of the electrostatic lens. Electrical-optics software was used to systematically investigate the behavior of the electron beam trajectory when the aforementioned variables were manipulated. The results of the experiment agree with the theoretical simulation results. Each variable has an individual effect on the electron beam focal spot size impinging on the target anode. An optimum condition of the parameters was obtained producing good quality of X-ray images. Also, MWCNT yarn was investigated for field emission characteristics and its contribution in the X-ray generation. The dry spinning method was used to fabricate MWCNT yarn from super MWCNTs, which was fabricated by MW-PECVD. The MWCNT yarn has a significant field emission capability in both diode and the triode X-ray generation structure compared to a MWCNT. The low-voltage-field emission of the MWCNT yarn can be attributed to the field enhancing effect of the yarn due to its shape and the contribution of the high-aspect-ratio nanotubes that protrude from the sides of the yarn. Observations of the use of filters on the development of X-ray images were also demonstrated. The amount of exposure time of the samples to the X-ray was also manipulated. The MWCNT yarn can be a good candidate for use in the low voltage field emission application of X-ray imaging.

• Journal of Advanced Marine Engineering and Technology
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• 제29권5호
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• pp.495-501
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• 2005

Al is a active metal that owes its resistance to a thin, protective, barrier oxide surface layer, which is stable in air and neutral aqueous solution. Thus Al alloys are widely used in architectural trim. cold & hot-water storage vessels and piping. However Al and most of its alloy may corrode with some forms such as pitting corrosion, intergranular corrosion and galvanic corrosion in the case of exposure to various industrial and marine atmosphere. Therefore a correct evaluation of corrosion resistance for their Al and Al alloys may be more important in a economical point of view. In this study. a relative evaluation of corrosion resistance for three kinds of Al alloys such as ALDC2, ALDC3, and ALDC8 series was carried out with electrochemical method. There is a tendency that corrosion potential is shifted to positive or negative direction by alloying components regardless of corrosion resistance. Moreover the data of corrosion properties obtained from cathodic Polarization curve, cyclic voltammogram and AC. DC impedance respectively showed a good correspondence each other against the corrosion resistance but variation of corrosion potential. passivity current density of anodic polarization curve and corrosion current density by Tafel extrapolation and Stern-Geary method didn't correspond with not only each other but also considerably the data of corrosion properties discussed above. Therefore it is suggested that an optimum electrochemical evaluation for corrosion resistance of Al alloy is to calculate the diffusion limiting current density of cathodic polarization curve, impedance of AC or DC and polarization resistance of cyclic voltammogram.

• Journal of Periodontal and Implant Science
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• 제23권1호
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• pp.127-134
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• 1993

The purpose of this study was to observe the control effect of hypersensitivity after periodontal treatment in the 19% microcrystalline hydroxyapatite containing toothpaste for the subject of 85 persons of both sexes, who complained hypersensitivity. At 2 weeks and 4 weeks after periodontal treatment, comparison of control effect was performed between the 19% microcrystalline hydroxyapatite containing toothpaste group and control group. The result were as follows, 1. The main causes of dentin hypersensitivity are the root exposure with gingival recession and cervical abrasion. 2. The occurance rate of hypersensitive tooth in the upper jaw was higher than that of the lower jaw, and more or less, the molar area showed more occlurance of hypersensitivity than the premolar and incisor area in both jaw. 3. Patients showed very sensitive response to the thermal stimulus, especially cold stimulus. 4. Exellent control effect of hypersensitivity in 19% microcrystalline hydroxyapatite containing toothpaste group showed 83.02% at 2weeks, 92.45% at 4weeks and these values were higher than the control group. In conclusion, we find that 19% microcrystalline hydroxyapatite containing toothpaste have the control effect of hypersensitivity and the proper toothbrushing method is the key in attaining more effectiveness of the toothpaste.

• 한국의류산업학회지
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• 제11권5호
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• pp.833-839
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• 2009

This study was to investigate the human's physiological responses and subjective sensations with wear trial through seasonal condition by age. Climate chamber was set $5^{\circ}C$, RH 45% for winter and $30^{\circ}C$, RH 65% for summer condition. Thirty male subjects were volunteered consisted of 10 people in their 20s, 40s, and 60s. In this study physiological responses such as rectal temperature, skin temperature, clothing microclimate, heart rate and blood pressure were measured. As for age, 60s was the highest in rectal temperature regardless of seasonal condition. In skin temperature, 40s was the highest in winter and 20s was the highest in summer. In clothing microclimate temperature and heart rate, 20s was the highest regardless of seasonal condition. And blood pressure was appeared the highest in 20s regardless of seasonal condition. Subjective sensations such as temperature sensation, wetness sensation and thermal comfort were measured. The subjects revealed that temperature sensation was higher 20s than 60s. Compare of other age group, 60s felt colder in the same environment and clothing. It suggested that temperature susceptibility in 60s became weakened showing no change sensation during the cold exposure. Wetness sensation was higher 20s than 60s. Thermal comfort of 60s was felt more discomfortable than any other age group. This means require the supplement of a suitable clothing in order to adjust to change of environmental conditions.

• Asian Pacific Journal of Cancer Prevention
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• 제17권sup3호
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• pp.59-64
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• 2016

Breast cancer (BC) is the most common cancer in females (27% of the total) and the main cause of death (16%) due to cancer in women in developed and developing countries. Variations in its incidence rate among geographical areas are due to various contributing factors. Since there have been a lack of studies on this topic in our country, the present spatial analysis of breast cancer incidence in Iran in 2009 was conducted using data from the national cancer registry system. The reported incidences of the disease were standardized according to the World Health Organization population and the direct method. Then data was inserted into the GIS software and finally, using the Hot Spot Analysis (Geties-Ord Gi), high-risk areas were drawn. Provinces with incidences 1.96 SD higher or lower than the national average were considered as hot spots or cold spots, at the significance level of 0.05%. In 2009, a total of 7,582 cases of BC occurred in Iran. The annual incidence was 33.2 per hundred thousand people. Our study showed that the highest incidence of BC in women occurred in the central provinces of the country, Tehran, Isfahan, Yazd, Markazi and Fars. The results of hot spots analysis showed that the distribution of high-risk BC was focused in central parts of Iran, especially Isfahan province (p <0.01). The other provinces were not significantly different from the national average. The higher incidence in central provinces may be due to greater exposure to carcinogens in urban areas, a Western lifestyle and high prevalence of other risk factors. Further epidemiological studies about the etiology and early detection of BC are essential.

• 폴리머
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• 제26권2호
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• pp.279-286
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• 2002

기능성고분자표면으로 개질하기 위해서 polyethylene(PE)표면에 아크릴산을 알곤 플라즈마를 이용하여 고정화와 그라프팅을 행하고 고정화와 그라프딩에 의한 개질효과를 ATR적외선스펙트럼의 분석, 접촉각과 접착강도 측정에 의하여 평가하였다. 아크릴산의 특성흡수띠와 접촉각의 현저한 감소사실로부터 친수성개질을 평가하였다. 그라프팅된 PE의 접촉각은 플라즈마처리시간에 따라서 무처리 PE에 비하여 47~$53^{\circ}$ 감소하였고 고정화된 PE는 이보다 작은 23~$26^{\circ}$ 감소하여 그라프팅이 고정화보다 더 효과적인 친수화 수단이 됨을 관찰할 수 있었다. 표면친수화의 정도는 플라즈마 처리시간과 방전출력에 강하게 의존하였다. 그라프팅의 경우 처리시간이 증가할수록 더욱 친수화되지만 고정화의 경우는 처리시간의 증가와 방전출력의 증가는 오히려 친수성을 감소시켰다. 개질된 PE표면의 peel test에 의한 접착강도측정 전파 역시 접촉각과 같은 경향을 나타내었다. 이러한 현상은 고정화과정 중에 아크릴산이 ablation되어 표면의 카복시친수성기가 감소하는 현상 때문으로 해석되었다.

• Applied Biological Chemistry
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• 제35권1호
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• pp.36-41
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• 1992

면실유, 옥배유 및 채종유의 산패도를 신속하고 재현성 있게 측정하고자 $60^{\circ}C$ 및 $70^{\circ}C$로 저장한 식용유의 pentanal과 hexanal을 headspace 가스크로마토그라피 방법으로 분석하였고, 그 결과를 관능검사 결과와 상관분석을 실시하였다. Headspace 가스크로마토그라피 방법에서 휘발성 산화생성물의 포집 및 용출은 cold trap-thermal desorption 방법으로 실시하였으며, GC 주입부에 들어가는 splitless mode glass liner insert에 Tenax GC를 충전하여 사용하였다. 23종의 휘발성 산화생성물이 gas chromatography 및 gas chromatography-mass spectrometry에 의하여 검출되었으며, 저장 기간에 따른 pentanal과 hexanal 함량 변화와 관능검사에 의한 산패취 측정 결과의 상관분석을 실시한 결과, pentana(PE), hexanal(HE) 및 log{PE) log(HE) $log(PE){\times}log(HE)$의 세 가지를 변수로 한 회귀식의 상관계수의 값이 각각 0.831, 0.866 및 0.896으로 다같이 높을 값을 보였다. 따라서 headspace 가스크로마토그라피를 이용하여 면실유, 옥배유 및 채종유의 휘발성 산화생성물 중 pentanal과 hexanal을 분석하면 각각의 식용유의 산패도를 객관적으로 평가할 수 있음을 알 수 있었다.

• Safety and Health at Work
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• 제3권4호
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• pp.268-277
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• 2012

Objectives: 1) To determine mercury levels in urine samples from garbage workers in Southern Thailand, and 2) to describe the association between work characteristics, work positions, behavioral factors, and acute symptoms; and levels of mercury in urine samples. Methods: A case-control study was conducted by interviewing 60 workers in 5 hazardous-waste-management factories, and 60 matched non-exposed persons living in the same area of Southern Thailand. Urine samples were collected to determine mercury levels by cold-vapor atomic absorption spectrometer mercury analyzer. Results: The hazardous-waste workers' urinary mercury levels (10.07 ${\mu}g/g$ creatinine) were significantly higher than the control group (1.33 ${\mu}g/g$ creatinine) (p < 0.001). Work position, duration of work, personal protective equipment (PPE), and personal hygiene, were significantly associated with urinary mercury level (p < 0.001). The workers developed acute symptoms - of head-aches, nausea, chest tightness, fatigue, and loss of consciousness at least once a week - and those who developed symptoms had significantly higher urinary mercury levels than those who did not, at p < 0.05. A multiple regression model was constructed. Significant predictors of urinary mercury levels included hours worked per day, days worked per week, duration of work (years), work position, use of PPE (mask, trousers, and gloves), and personal hygiene behavior (ate snacks or drank water at work, washed hands before lunch, and washed hands after work). Conclusion: Changing garbage workers' hygiene habits can reduce urinary mercury levels. Personal hygiene is important, and should be stressed in education programs. Employers should institute engineering controls to reduce urinary mercury levels among garbage workers.

• 한국식품영양과학회지
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• 제21권4호
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• pp.460-470
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• 1992

BAT는 신생아를 비롯하여 동면을 취하는 동물 그리고 설치류에 주로 많은 양이 분포되어 있으며, 세포내지방산을 산화시켜 열을 방출하여 체온조절 및 에너지균형 조절자로서 중요한 역할을 하고 있다. 그러므로 에너지 균형 조절을 통한 체중 조절을 통하여 비만과 밀접한 관련성을 맺고 있는 것으로 보인다. 유전적으로 비만인 실험동물의 경우에는 주로 주위온도, 식이량과 그 구성.성분비 변화와 같은 자극에 대해 민감하게 반응을 일으키지 못해 BAT의 열생성 결함으로 비만이 초래되는 것으로 보인다. 인간의 경우에 있어서는 어느 정도 실험동물의 경우와 비슷한 양상을 보이나, 체내 BAT의 분포량이나 BAT의 연소기질인 지방산의 합성능력 등에 많은 차이점들이 있기 때문에 실험동물의 경우를 인간에게 그대로 적용시킬 수는 없다. 뿐만 아니라 인간을 대상으로 연구하는 데에는 몇가지 문제점들이 있다. 우선 사람의 나이, 성, 실험시작전 영양상태, 스트레스 정도, 유전적 배경 그리고 날씨 에 대한 적응능력에 따라서 열생성 정도가 달라지므로 실험결과에 대한 정확한 해석을 하기가 어렵다. 또한 신생아에 비해서 성인의 경우 BAT의 양이 소량이고 분산되어 있기 때문에 BAT량 결정에 어려움이 있고 열생성 정도와 에너지 소비율과 같이 BAT의 열생성 기준을 나타내는 실험방법에도 많은 문제점이 있는 것으로 나타났다. 그러므로 많은 사람을 대상으로 하여 좀더 정확한 측정방법의 개발을 통해서 열생성에 미치는 타 요인들을 배제 시켜 실험을 하여 소비되는 에너지량을 정확하게 산출하고 BAT의 열생성 기전과 자극원인을 명확히 규명한다면 비만의 치료에 많은 도움을 줄 것으로 생각된다.

• Journal of Chest Surgery
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• 제14권4호
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• pp.381-387
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• 1981

Fourteen Infants with congenital cardiac anomalies underwent primary surgical Intervention within the first 12 months of life. There were eight patients with ventricular septal defect, two with total anomalous pulmonary venous return [TAPVR], and the remainders with tetralogy of Fallot, transposition of great arteries [d-TGA], Taussing-Bing malformation, and coronary A-V fistula. The age of the patients ranged from 5 to 12 months, with a mean age of 9.9 months. The mean weight was 6.7 Kg [3.8 to 9.5 KS]. Congestive heart failure persisting despite intensive medical treatment was present In 8 patients [56%], and was the most common indication for operation. Early operation was necessary in 5 of these patients [35%], because of failure to thrive and recurrent pulmonary infection. In one patient with TOF, frequent hypoxic spell prompted the necessity for early operation. In cases of VSD, TAP. VR, TOF, and coronary A-V fistula, Intracardiac repair was done with conventional cardiopulmonary bypass, chemical cold cardioplegia, and topical myocardial cooling. Deep hypothermic circulatory arrest with surface induced cooling, followed by core cooling and core rewarming, was employed .for better exposure in the cases of d-TGA and Taussing-Bing malformation. The results were however, not satisfactory. The overall mortality was 28 per cent. There were no deaths in the eight patients with VSD. The one with coronary A-V fistula survived. The other 5 cases all expired either on the table or immediately after operation. The non-fatal post-operative complications included low cardiac output, respiratory insufficiency, bleeding, and temporary A-V block. The causes of death were prolonged circulatory arrest time in d-TGA, complete A-V block and low cardiac output in TOF and Taussing-Bing malformation and prolonged bypass time and Inadequate correction in TAPVR.