폐플라스틱/제강 Dust 성형체의 용출안전성에 대한 연구

강영구,송종혁 한국안전학회 2003 한국안전학회지 Vol.18 No.4

In this study, We have investigated leaching characteristics of heavy metals for recycled plastic composites containing EAF(Electric Arc Furnace) dust & EAF slag. EAF dust & EAF slag used that is generated in the 3 steel-malting companies in domestic. The physical and chemical properties of EAF dust & slag was examined by measuring specific surface area, porosity, oil absorption test and chemical wetting analysis etc. Results of total analysis indicated that EAF dust, slag contained significant amount of hazardous metals such as Cu, Pb, Cd and Cr. But, In the leaching test of the recycled plastic composites containing EAF dust, slag by Korean Standard Leaching Procedure, composites shows much lower leaching concentration of heavy metals. It was concluded that the recycled plastic composites containing EAF dust, slag showed good physical and chemical characteristics. This means that the EAF dust, slag can be effectively used as a functional filler.

항진균물질 KP-3 생산균주의 분리동정 및 항생물질의 정제

강선철,박영구 대구대학교 과학기술연구소 1995 科學技術硏究 Vol.2 No.1

A bacterium producing an antifungal compound KP-3 isolated from soil was selected and identified as Bacillus sp. B-003. The antibiotic substance KP-3 was active against Microsporum gypseum, Trichophyton rubrum and Epidermophyton floccosum at the concentrations of 0.15 - 10.0 ㎍/ml except Candida albicans. This compound was isolated from the fermentation broth (12L) and completely effected by chromatography on silica gel. The Rf value of purified KP-3 (5mg) was 0.91 when TLC plate was developed with methanol - ethyl acetate (1.5, v/v).

공정안전용 Polymer PTC 소재의 제조 및 특성

강영구,조명호 한국안전학회 2003 한국안전학회지 Vol.18 No.3

Polymeric positive temperature coefficient(PTC) composites have been prepared by incorporating carbon black(CB) into high density polyethylene(HDPE), polyphenylene sulfide(PPS) and polybutylene terephthalate(PBT) matrices. A PTC effect was observed in the composite, caused by the large thermal expansion due to the consecutive melting of HDPE, PPS and PBT crystallites. This theory is based upon the premise that the PTC phenomenon is due to a critical separation distance between carbon particles in the polymer matrix at the higher temperature. The influence of PTC characteristics of the PPS/CB composite can be explained by DSC result. HDPE, one of prepared composition, exhibit the higher performance PTC behavior that decreaseing of negative temperature coefficient(NTC) effect and improved reproducibility by chemically crosslinking. Also, PBT/CB and PPS/CB composites exhibit the higher PTC peack temperature than HDPE/CB PTC composite, individually 200℃and 230℃. These FTC composite put to good use in a number of safety application, such as self-controlled heater, over-current protectors, auto resettable switch, high temperature proctection sensor, etc.

내시경적 점막절제술로 치험한 식도 과립상 세포종 1례

강혁주,김성욱,최석진,이중현,장재식,서영범,윤병구,박건욱,김성자,김용섭,강승완,이구,양창헌,이창우,김욱년,이광헌,서정일 동국대학교 의학연구소 2000 東國醫學 Vol.7 No.-

과립상 세포종은 Schwann 세포 기원으로 생각되며 인체에 비교적 드물게 발생한다. 과립상 세포종은 전신 어느 곳에서나 발견될 수 있으나 주로 혀, 구강, 피부 혹은 유방 등에서 호발하며 드물게 위장관에서 발견된다. 위장관에서는 식도에서 가장 호발하며 다음으로 위, 대장 순이다. 과립상 세포종은 대부분, 특히 위장관에서는 양성이며 소수의 악성 병변이 보고되었다. 이러한 이유와 함께 수술 전의 진단이 어렵기 때문에 과립상 세포종에 대한 근본적인 치료는 현재까지 외과적 절제술이다. 최근에 시도되는 치료방법들로는 내시경적 레이저 치료, 용종절제술, 내시경적 점막 절제술 등이 있다. 저자들은 상부 소화관 내시경검사를 시행하여 식도 과립상 세포종을 진단하고 내시경적 점막 절제술을 시행하여 합병증 없이 퇴원하여 현재 재발없이 경과 관찰중인 1례를 경험하였기에 보고하는 바이다. Granular cell tumors, which occur infrequently, are probably of Schwann cell origin. They can occur almost anywhere in the body but usually affect the tongue, oral cavity, skin, or breasts and are rarely found in the gastrointestinal tracts. The esophagus is the most frequent gastrointestinal site, followed by the stomach and the colon. Granular cell tumors are generally benign, especially in the gastrointestinal tract, some malignant lesions have been reported. For this reason, and also because preoperative diagnosis is difficult, the standard treatment for granular cell tumor has until now been surgical excision. In recent years, other therapeutic methods is endoscopic laser therapy (ELT), polypectiomy, endoscopic mucosal resection (EMR). We report a case of esophageal granular cell tumor which was diagnosed by an endoscopy and managed using an endoscopic mucosal resection without complication.

공정안전용 Polymer Blend형 습도센서의 특성 연구

강영구,조명호 한국안전학회 2004 한국안전학회지 Vol.19 No.3

Conductive polymer blends and composites are widely used for different safety application such as electrostatic charge dissipation(ESD), electromagnetic interference(EN/U) shielding, electrostatic prevention and safety chemical sensor. In order to prepare a impedance-type humidity sensor that is durable at high humidities and high temperature, electically conductive polymer blends based on dial lyldimethylammonium chloride(DADMAC) and epoxy were prepared in this study. The polymer blends type conductive ionomer exhibits reaction each other DADMAC and epoxy in MIR and DSC analysis. The blends material was traced by new peak at 1600cm-1 and appeard improvement of thermal resistance by melting point shift. Alumina substrate was deposited a pair of gold electrodes by screen printing. The blend material were spin-coated with a thin film type on the surface of alumina substrate. The polymer bleld type sensor exhibits a linear impedance increasing better than DADMAC coated humidity sensor. Also it shows good sensitivity, low hysteresis and durability against high humidity.

녹제거 폴리머겔의 제조 및 특성

강영구,김정훈 한국안전학회 2004 한국안전학회지 Vol.19 No.2

The formation of rust on metallic substrate is known to cause the damages and destructions of raw materials, which is one of the leading reasons of structural collapses and many kind of hazards in modem industry. Polymer gels with rust removing effects were compounded in this study by employing various kinds of acids like hydrochloric acid, phosphoric acid, gluconic acid, oxalic acid as the rust removing ingredients. TEA(Triethanolamine) as dispersant and hydrophilic chemical were used for effective gelation of acids. Also corrosion inhibitor was added to enable the coating effect and to improve rust removing effect on metallic surface. In order to investigate the rust properties on metallic substrate, artificial rusts were prepared in salt solution, using iron, copper, aluminium and brass as the base metals. The properties of gel compounds were checked by gelation, pH, viscosity, morphology property and rust removing test. Developed gel compounds in this study have a good rust removing property, showing a strong adhesion on horizontal and vertical metallic surface, and can be easily rinsed off by water.

폴리올레핀계 폐플라스틱/복합filler 성형체의 난연성 및 기계적 물성 연구

강영구,송종혁 한국안전학회 2003 한국안전학회지 Vol.18 No.2

Flame retardancy and mechanical properties of recycled polyolefinic plastics/inorganic filler composite systems were investigated by using several inorganic flame retardants such as magnesium hydroxide and slag powder generated electro arc furnace. Compatibilizer used each maleic anhydride functionalized polyethylene (PE-g-MAH) and polypropylene(PP-g-MAH) or used mixture of these. The effect of polymeric compatibilizers on the properties of composites was studied by tensile and impact test, differential scanning calorimetry, morphology in the changed fracture mechanism. The improved adhesion was particularly reflected in the mechanical properties. The flame retardancy of composites was examined by measuring limiting oxygen index(LOI, ASTM D2863), smoke density(ASTM D2843) and vertical burning test(UL94). Regarding the flame retardant effect, the EAF slag powder is behaving as synergists as they are only active in the presence of magnesium hydroxide.

제강Slag 충진 폐플라스틱/복합 전도성 filler 복합재료의 전자파 차폐 효과

강영구,송종혁 한국안전학회 2004 한국안전학회지 Vol.19 No.4

Electromagnetic interference(EMI) shielding characteristics of composite filled with Cu flake and carbon brush powder as hybrid conductive filler and EAF slag have been studied. The coaxial transmission line method of ASTM D4935-99 was used to measure the EMI Shielding effectiveness of composites as formulation in frequency rage 100~1,000MHz. The SE also increases with the increase in filler loading. The hybrid filler filled composites show higher SE compared to that of only Cu flake. The correlation between SE and conductivity of the various composites is also discussed. The results indicate that the composites having higher filler loading(≥40wt.%) can be used for the purpose of safety materials to protect hazardous electromagnetic interference.

Gel형 인화성 용제 Compound의 특성

강영구,김정훈 한국안전학회 2003 한국안전학회지 Vol.18 No.3

Gel-like compounds containing flammable solvents were prepared to use for cleaning agents in field of innovative industries and general purposes. And experiments were conducted to improve the defects of liquified flammable solvents from the view point of safety and health hazards. Flammable solvents used in this study were several single component flammable solvents(turpentine oil, N-methyl-2- pyrrolidone(NMP), d-limonene) and multi component flammable solvent(gasoline and ethanol). For gelation of flammable solvents, commercially known as Aerosil® 200 fumed silica and triethanolamine(TEA) were used as gelation agent, dispersant. The analyses on properties of gel-like compounds was studied by gelation and viscosity test, pH test, volatility test and differential scanning calorimetry(DSC) measurement. The experimental results indicate that gel-like compounds containing flammable solvents have pH stability, high viscosity, volatile organic compounds(VOC) control by the decrease of volatility and odor component generation, fluidity control etc. From the experimental values, it can be predicted that the safety in the working place is improved by manufacturing flammable solvents into gel-like compounds.

한국인 정상교합자의 natural head position시 안모의 연조직에 대한 측모두부방사선학적 분석

강승구,이영준,박영국 대한치과교정학회 2003 대한치과교정학회지 Vol.33 No.5

이 연구의 목적은 한국인의 연조직 측모두부방사선학적 기준치를 설정하고, 이를 성별간, 인종간 비교하여, 한국인의 치아안모 변이를 위한 교정적 진단과 치료계획을 확립하기 위한 한 가지 기준을 제안하고자 하는데 있다. 저자들은 균형 잡힌 안모를 가진 젊은 한국인 성인 남녀 각 27명, 20명을 선발하였다. 이들의 평균연령은 남자 23.8±2.6세, 여자 22.5±1.7세였다. 높은 신뢰성과 재현성을 가진 natural head position에서 측모두부방사선사진을 촬영하였고, 필름을 트레이싱한 뒤 Arnett등이 소개한 분석요소들을 이용하여 계측하였다. 그 결과를 독립 모수 검정을 통하여 한국인 남녀를 우선 비교하였고, 한국인 남녀 각 군을Arnett등이 제시한 백인들의 남녀 기준치와 비교하였다. 그 결과로부터 다음과 같은 결론을 얻을 수 있었다. 한국인 남자는 한국인 여자보다 전반적으로 비후한 하안모 연조직과 작은 비순각, 긴 안면고경, 깊은 측모상, 그리고 더 돌출된 하안모를 가지고 있었다. Arnett등이 제시한 백인 기준치와의 비교에서는 한국인이 남녀 모두에서 덜 노출되는 상악 절치를 제외하고는 전반적으로 더 긴 안면 길이를 보였고, 더 짧은 측모 깊이를 보였다 또한 두 인종 모두상악 구조물들은 TVL에서부터 유사한 수평적 위치에 있었으나, 한국인 군에서 유의성있는 상악-하악간 전후방적 거리차를 나타내었다. 이는 한국인이 백인에 비해 기준선인 TVL로부터 하악 구조물들이 상대적으로 더 후퇴되어 있음을 의미한다고 할 수 있다. 균형잡힌 안모를 가진 개체의 안면각은 성, 인종에 상관없이 170도 전후를 나타내어 보편적으로 신뢰할 만한 평가항목으로 사료되었다. This study was performed to establish Korean soft tissue cephalometric norms, to compare the norms between sexes and between races, and then to suggest a guideline to execute orthodontic diagnosis and treatment planning for dentofacial deformities in Korean. Young Korean adults were selected. They were 27 males (23.8±2.6-year-old) and 20 females (22.5±1.7-year-old) who had harmonious facial balance. After taking lateral cephalograms under the natural head position which is widely known as a highly reliable and reproducible reference position, films were traced and analysing factors were measured as introduced by Arnett et al. Comparisons were done between male and female groups and between Korean and Caucasian groups using unpaired t-test. From the results it was concluded that Korean male had generally thicker lower facial soft tissue and smaller nasolabial angle, longer facial height, deeper facial depth, and more protrusive lower face than Korean female. From the comparison with Caucasian norms adopted from the research of Arnett et al., both Korean male and female showed longer facial lengths generally except less exposed maxillary incisor, and shorter facial depth than Caucasian counterparts. Also, both races showed similar horizontal position of maxillary structures from TVL (true vertical line), but there were more significant anteroposterior differences of maxilla-mandible in Korean groups. These results mean Korean had relatively more retruded mandibular structures from the reference line, TVL. Individuals who had harmonious facial balance showed similar facial angle, more or less 170 degree, regardless of sexes or races.