• 전기화학회지
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• 제15권4호
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• pp.230-235
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• 2012

분자량이 각각 300(PEGMA300) 및 1100(PEGMA1100) g $mol^{-1}$인 PEGMA와 합성된 $BF_3LiMA$ 리튬염을 이용하여 다양한 조성의 고분자전해질을 제조하고 전기화학적 특성을 평가하였다. 흥미롭게도 AC-impedance 측정법에 의한 상온 이온전도도는 분자량 $300g\;mol^{-1}$로 합성된 액체 고분자전해질에서 $8.54{\times}10^{-7}S\;cm^{-1}$의 값이 얻어진 반면, PEGMA1100으로 합성된 고체상태의 고분자전해질에서 최대 14배 이상 높은 $1.22{\times}10^{-5}S\;cm^{-1}$가 관찰되었다. 이러한 결과는 PEGMA에 ethylene oxide 단위가 5개인 $300g\;mol^{-1}$보다 23개인 $1100g\;mol^{-1}$에서 리튬이온의 배위가 쉽게 일어나기 때문으로 해석된다. 또한 양이온 수율 측정결과 리튬메탈과 $BF_3$간의 반응으로 인해 0.6의 비교적 낮은 값이 나왔지만 초기 3000초 동안에는 0.9 이상의 값이 관찰되어 단일이온 전도체의 특징을 보여주었다.

• 한국축산식품학회지
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• 제28권3호
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• pp.373-389
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• 2008

This study was conducted to evaluate exposure level and risk of heavy metals in livestock foodstuffs and Korean foods. Based on the "Food Intake Data," a part of the 2005 National Health & Nutrition Survey and the "2005 Seasonal Nutrition Survey", 113 Korean foods items were selected. 3 samples from different manufacturers of each 113 items of Korean foods were purchased on summer and fall, so total 678 samples were used. The food groups were classified into 15 categories. For the livestock foodstuffs category, meats and poultry (chicken, pork, pork belly, beef, beef feet soup), milks and dairy products (milk, ice cream, liquid yoghourt, sherbet), eggs (egg) were selected. It was found that the daily amount of heavy metals intake (mg/person/day) from livestock foodstuffs is 0.00020 arsenic, 0.00000 cadmium, 0.00020 lead, and 0.00006 mercury, and the daily amount of heavy metals intake (mg/person/day) from Korean foods is 0.0265 arsenic, 0.0083 cadmium, 0.0067 lead, and 0.0028 mercury. Daily amount of heavy metals intake from livestock foodstuffs was low among the food groups. For risk assessment, PDI (Probable Daily Intake) was calculated and compared with PTWI (Provisional Tolerable Weekly Intake) of JECFA (Joint FAO/WHO Expert Committee on Food Additive). Relative hazard of these livestock foodstuffs was 0.006% in arsenic, 0.000% in cadmium, 0.085% in lead, and 0.149% in mercury. Relative hazard of Korean foods was 0.941% in arsenic, 14.676% in cadmium, 3.319% in lead, and 6.860% in mercury. Thus, livestock foodstuffs and Korean foods were as safe as satisfied with the recommended standards of JECFA.

• 대한화장품학회지
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• 제37권1호
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• pp.75-81
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• 2011

본 연구에서는 유산균 발효에 의한 인삼열매 추출물의 여러 가지 생리활성을 평가하였다. 고성능액체크로마토그래피를 수행하여 인삼열매 추출물과 유산균 발효 인삼열매 추출물의 ginsenoside Re, Rc 및 Rb1의 함량분석 결과 유산균 발효에 의해 ginsenoside Re, Rc 및 Rb1의 함량이 모두 증가하였다. 인삼열매 추출물과 유산균 발효 인삼열매 추출물의 DPPH free radical 소거활성과 SOD 유사활성 측정결과 1.00 %의 농도에서 유산균 발효 인삼열매 추출물은 각각 86.34, 76.82 %의 DPPH free radical 소거활성과 SOD 유사활성을 나타내었고, 인삼열매 추출물은 각각 49.78, 40.80 %의 DPPH free radical 소거활성과 SOD 유사활성을 나타내어 유산균 발효에 의해 항산화 활성이 증가하는 것을 확인하였다. 또한 유산균 발효 인삼열매 추출물 0.50 %의 농도로 처리한 피부 섬유아세포에서 procollagen type I (COL1A1)은 828.13 % 증가하였으며, matrix metalloproteinase (MMP)-1은 87.88 %, tumor necrosis factor (TNF)-${\alpha}$는 99.92 %감소하는 효과를 보여주었다. 이처럼 항산화, 주름, 항염에 효능을 보이는 유산균 발효에 의한 인삼열매 추출물은 기능성 화장품 소재로 개발될 수 있는 가능성이 있다.

• 한국치위생학회지
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• 제12권3호
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• pp.513-520
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• 2012

Objectives : In this study, contact angle and shore D hardness were measured, and a shark fin test was conducted after selecting five addition silicon(Blu-Mousse, BM; EXABITE II, EX; PERFECT, PF; Regisil$^{(R)}$ Rigid, RE; Silagum$^{(R)}$, SI) in order to figure out the properties of elastomeric interocclusal recording materials and reduce errors at interocclusal recording. 8) Methods : A contact angle was measured using a contact angle analyzer. After placing a drop of liquid on the surface of the specimens of interocclusal recording materials, a contact angle was photographed with a CCD camera on the equipment. In terms of a shark fin test, interocclusal recording materials were mixed for the time proposed by the manufacturer and inserted into the split ring of the Shark fin device. Twenty (20) seconds exactly, a metal rod was removed to make the materials slowly absorbed. Once they hardened, fin height was measured with a caliper after separating molds and trimming the specimens. The shore D hardness was measured with a shore D hardness tester(Model HPDSD, Hans Schmidt & Co. Gmbh, Germany) in sixty (60) minutes after fabricating specimens. In each experiment, five specimens, mean and standard deviation were calculated. A one-way ANOVA test was performed at the p>0.05 level of significance. In terms of correlation among the tests, Pearson correlation coefficient was estimated. For multiple comparison, Scheffe's test was carried out. Results : A contact angle was the highest in EX with $99.23^{\circ}$ (p<0.05) while the result of the shark fin test was the longest in RE with 5.45mm. SI was the lowest (0.27mm) with statistical significance. Among the interocclusal recording materials, significant difference was observed in terms of means (p<0.05). The shore D hardness was the highest in SI with 31.0 while RE was significantly low with 16.4 (p<0.05). Among the materials, statistically significant difference was observed in terms of means when compared to the rest materials (RE), BM, RE and SI (PF and EX) and the remaining materials (BM and SI) (p<0.05). In terms of correlations among the tests, a negative correlation occurred between shore D hardness and shark fin test(r=-0.823, p=0.000). Conclusions : According to the study above, it is necessary to understand the properties of interocclusal recording materials and consider contact angle, shark fin test and properties of shore D hardness to select appropriate materials.

• 대한치과보철학회지
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• 제37권6호
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• pp.741-755
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• 1999

As a material of metal-ceramic prosthesis, nickel as a form of Ni-Cr alloy has been used for many dental prostheses in many cases. However, several problems in use of the alloy have been revealed (ex : tissue stimulation, skin allergy, hypersensitivity, cytotoxicity and carcinogenecity). Little is known about nickel with respect to the relationship between Ni-prosthesis and gaining of Ni-resistance in oral microorganisms. The present study was undertaken to check wheather use of Ni-prosthesis leads to occurrence of Ni-resistant microorganisms. So this study may suggest the possible relationships between the oral microorganisms and nickel-resistance in oral environment. Bacteria were isolated from the gingival crevicular fluid on the pateints wearing Ni-Cr prosthesis. The isolated bacteria were tested for their Ni-resistance in nickel containing media at different concentration from 3mM to 110mM. E. coli HB101 was used as control. The Ni-resistant bacteria were isolated and biochemically identified. The Ni-resistant bacteria were tested several bio-chemical, molecular-biological tests. Performed tests were ; measuring the growth curve, antibiotic test, growth ability test in liquid media, isolation of the chromosome and plasmid, digestion of DNA by restriction enzyme, electrophoresis of chromosome and plasmid DNA, identification of Ni-resistant genes by the DNA hybridization. The results were as follows: 1) The bacteria isolated from gingival crevicular fluid on the patients wearing Ni-Cr alloy pros-thesis showed nickel-resistance. 2) The isolated microorganisms grew at nickel containing media of high concentrations (60mM-110mM). 3) Based on the biochemical tests, the isolated microorganisms were identified as Enterococcus faecalis(13 cases), Klebsiella pneumoniae(1 case) and Enterobacter gergeviae(1 case). 4) Enterococcus faecalis expressed not only nickel resistance but also the multi-drug resistance to several antibiotics ; chloramphenicol, kanamicin, streptomycin, lincomycin, clindamycin. However, all strain showed the sensitivity against the tetracycline. 5) DNA hybridization result suggest that there is no homology between the previousely known gene of nickel resistance in Klebsiella pneumoniae and chromosomal DNA of Enterococcus faecalis.

• Korean Chemical Engineering Research
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• 제51권6호
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• pp.745-754
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• 2013

본 연구에서는 유해원소로 오염된 현장토양을 대상으로 물리적 및 화학적 토양세척공법을 적용하였을 경우, 유해원소의 처리효율과 더불어 토양세척공법에서 발생하는 폐수를 중화, 응집, 흡착 반응을 이용하여 처리할 경우를 고려하여 최적 토양세척공법의 선정방법을 평가하고자 하였다. 본 연구에서 사용한 토양에서 주된 유해원소인 비소제거에 수산화나트륨 수용액이 황산 수용액보다 효과적이었다. 반면, 폐수 처리의 경우 수산화나트륨 수용액으로 토양 세척 시 함께 추출되는 토양유기물로 인하여 폐수처리가 복잡하고 유해원소의 제거가 잘되지 않아 세척공정의 세척제로는 산을 이용하여 토양을 세척하는 것이 좋으며, 발생하는 세척액의 pH를 6.5 이상으로 중화시켜 대부분의 유해원소를 제거할 수 있었다. 흡착제로 GFO(Granular ferric oxide)를 이용하였을 경우 비소와 납의 제거율이 뛰어났으며, 중화공정과 결합하였을 경우 대부분의 유해원소를 제거할 수 있었다. 결과적으로, 토양세척 공법 적용 시 토양의 특성에 따라 유해원소의 제거율 및 세척액의 처리 및 재이용 방법이 차이가 있으므로, 세척효율 및 세척수 처리 공정을 고려한 체계적인 최적화를 진행하여야 할 것으로 판단된다.

• 대한한의학방제학회지
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• 제24권2호
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• pp.80-99
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• 2016

Objectives : Instrumental chemical analysis was utilized to investigate the effect of Add-Omit-Saenghyeoryunbu-eum(AO-SHU) on diabetic treatment. One of the most exciting, yet also controversial, arguments is the safety and biological mechanisms of the natural medicine on human body. Therefore, the aim of this study is to provide a better understanding on bioactive chemical components, hazards of heavy metal contamination and biological mechanism of the diabetic medicine composed of 12 different natural herbs. Methods : To study bioactive compound and metallic component in the diabetic medicine in detail, LC-MS/MS (Liquid Chromatography-Mass/Mass), GC (Gas Chromatography) and ICP (Inductively Coupled Plasma) were utilized to characterize the extract of the diabetic medicine and the result was compared with 18 marker substances selected from literature survey. In addition, in vitro assay experiments including GPR 119 activity and human DGAT-1 inhibition, and OGTT (Oral Glucose Tolerance Test) were performed to verify the effectiveness of this medicine on diabetic treatment. Results : Out of 18 marker substances, 9 bioactive compounds were identified from LC-MS/MS analysis which include Citruline, Catalpol, Berberine, Ginsenoside Rb1, Ginsenoside Rg1, Oleanolic acid, β-Sitosterol, Mangiferin, and Schizandrin. ICP study on 245 residual pesticides revealed that 239 species were not detected but 6 species, Dimethomorph, Trifloxystrobin, Pyraclostrobin, Isoprocarb, Carbaryl and Flubendiamide, while the amounts are trace levels, below permitted concentrations. The biological activity was observed in vitro assay and Oral Glucose Tolerance Test(OGTT), which are consistent with a preliminary clinical test result, a drop in blood sugar level after taking this herbal medicine. Conclusions : Instrumental chemical analysis using LC-MS/MS, GC, and ICP was conducted successfully to identify bioactive compounds in AO-SHU for the treatment of diabetes, finding 9 bioactive compounds. Furthermore, in vitro assay experiments and OGTT show that AO-SHU has its biological activities, which imply that it can be a candidate for the future diabetes remedy.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.202-210
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• 2005

In this study, the fly ash was employed as a possible alternative to the bentonite for its high sorption capacity against cationic heavy metal. To consider the constituents of barrier possibly used, the specimens were mixed with different material contents (fly ash : weathered soil : bentonite), then sorption test was performed. Also the specimens were molded on the wet side of optimum moisture contents like mixing ratio of sorption test and their hydraulic conductivities were measured in flexible-wall permeameters. And to confirm the effect of dissolved cations, the hydraulic conductivity tests were repeated by converting the permeant liquids from water to $Cd^{2+}$ solution. Finally, the Cd-concentration at the effluent was analyzed for 500hrs to compare the effectiveness of each specimen in contaminant retardation. Test results showed that the more the ratio of fly ash increase, the more Kd value increase, and the hydraulic conductivity of weathered soil/bentonite (95:5) mixture was the lowest $(2.9*10^{-8}cm/sec)$, and specimens made of fly ash and fly ash/weathered soil mixtures showed similar hydraulic conductivity. Although the permeant liquid was changed from water to $Cd^{2+}$ solution, the hydraulic conductivity of all specimens except for weathered soil maintained similarly like before. Consequently, the initial breakthrough point of Cd in weathered soil specimen was observed at about 5hrs after the test started while that of fly ash specimens was not observed during the whole test period of 500hrs. The results implied that fly ash had a sufficient retardation capacity against contaminant transport possibly by its high sorption capacity although it showed little effect on the reduction of hydraulic conductivity. Based on the test results, it could be concluded that the fly ash can be possibly used as a suitable barrier material in containment system to attenuate the contaminant transport for its high retardation capacity and for the low cost.

• 자원환경지질
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• 제40권5호
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• pp.563-574
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• 2007

LIBS는 시료 표면에서 발생된 플라즈마로부터 방출되는 원자들의 분광선을 측정함으로써 물질의 화학적 조성을 감지, 확인, 정량화할 수 있는 최신의 분석기술로 기존의 전형적인 원소분석방법에 비해 현장분석기술로서의 더 많은 장점을 가지고 있다. LIBS는 최소한의 시료로 복잡한 분석과정을 피함으로 신속한 분석을 가능케 하고, 기기의 다방면적의 적용가능성과 단순함으로 인해 신속하게 가스, 고체, 액체상에서 다원소를 동시에 분석할 수 있는 레이저 기반의 분석기술로 지구화학적 분석, 탐사 혹은 환경분석에서 현장 이동성을 가진 센서로의 가능성 측면에서 매력적인 도구가 된다. 그러나 현장분석기술로서 토양환경에 적용하기에는 여전히 해결해야 할 문제들이 있다. 문헌연구를 통해 기본적인 작용원리인 플라즈마 형성과 물질붕괴과정을 고찰하고 현장분석기술로서 LIBS의 현 위치를 살펴본다. 또한 토양환경에 적용하기 위해 매질의 특성, 레이저 특성 및 분석신호에 영향을 미치는 다양한 인자들을 살펴보아 LIBS에 대한 기본적 이해를 돕고자 한다. 또한 분석에 미치는 영향 인자들을 보정해 분석 결과의 정확도, 정밀도 및 검출 한계 등 분석의 질을 향상 시킬 수 있는 기법 등을 다양한 문헌 연구를 통해 살펴봄으로써 추후 국내 토양환경분야의 LIBS 현장기술의 적용가능성을 고찰해보고자 한다.

• 융합신호처리학회논문지
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• 제19권2호
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• pp.61-67
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• 2018

용접예열은 본 용접 전에 금속이 융착되는 모재면을 일정한 온도로 가열하는 것을 의미한다. 냉각속도 조절에 따른 재료 경화 정도 감소, 불순물 편석억제, 열적 변형방지, 그리고 수분제거 등 인접 영향부의 균열을 방지할 수 있다. 이러한 이유에서 고품질의 용접을 위하여 반드시 필요한 작업이다. 유도가열은 전자기유도 현상을 응용하여 전기에너지를 열에너지로 변환시키는 효율적인 가열방식이다. 기체 및 액체를 이용한 연소발열과 비교하여 신속한 가열뿐만 아니라 청결하고, 안정적이며, 경제적이다. 단순한 구조로 주파수와 코일의 형태를 변형하여 가열체의 형상, 깊이, 재질에 관계없이 가열할 수 있다. 본 논문에서는 유도가열 기법을 이용하여 저주파 용접예열 시스템을 구현하였으며, 3종의 자동차 변속기 부품을 대상으로 권선코일 내에서 각 변속기 높이에 따라 권선코일 저항, 인덕턴스 및 자동차 변속기 부품의 온도변화를 관찰한 결과 전류의 변화는 저주파 가열에 있어 매우 중요한 요인으로 작용함을 확인하였다.