市乳의 貯藏期間에 따른 耐冷性 微生物 및 化學的 特性의 變化에 關한 硏究

이수원,강일수,양희진,백승천 성균관대학교 생명과학자원연구소 1997 生命資源科學硏究 Vol.4 No.1

The present study was conducted to predict shelf life of pasteurized milk with analysis of volatile compounds and sensory evaluation of milk to growth of psychrotrophic bacteria. Pseudomonas fluorescens KFRI 00194 inoculated concentration of 10^4 cfu/㎖ to observe of changes on sensory evaluation and volatile compounds of pasteurized milk. The results obtained in these experiments were summarized as follows; The psychrotrophic bacteria number at 4℃ were increased 6.39×10 exp(4)cfu/㎖ until first day and 2.20×10 exp(6)cfu/㎖, 1.17×10 exp(7)cfu/㎖ after 5 and 10days, respectively. The volatile compounds were shown the decreasing tendancies in acetaldehyde, ethanol depending on storage days, especially ethanol contents were significantly decreased between 5 and 10days storage(P<0.05). Diacetyl, 2-heptanone, 2-butanone and 3-methyl-1-butanol were shown the increasing tendencies of contents. Diacetyl, 2-heptanone and 2-butanone were significantly increased between 5 and 10days, 1 and 5days, 5 and 10days and 1 and 5days, respectively(P<0.05). However, 3-methyl-1-butanol was shown a increasing tendancy depending on storage days but the significantly different was not recognized. The changes of sensory evaluation were rapidly decrease from 6.8point first day to 4.2point after 10days and the decrease of organoleptic acceptability was significantly different recognized(P<0.05), excepted of 1 and 2days. The organoleptic acceptability according to increasing of psychrotrophic bacteria numbers were decreased. The organoleptic acceptability depending on changes of volatile compounds were shown to a conversed correlation coefficient with the exception of acetaldehyde and acetone. Especially, 2-heptanone, 2butanone and 3-methyl-1-butanol were gradually decreased of acceptability by the contents.

기종점통행량 추정방법의 발전과 연구방향

白承杰,李壽長 江南大學校産學技術硏究所 1998 산학기술연구소논문집 Vol.- No.6

장기 입원환자의 구강위생상태에 관한 실태 조사연구

이백현,신승철 단국대학교 치의학연구소 1990 논문집 Vol.2 No.-

The author have studied the status of oral health survey & snyder test in order to find out oral health levels of medical hospitalized patients. 72 patients volunteers age of 20 to 40, hospitalized at department of general surgery or pediatric surgery in K & J hospitals located in Seoul were participated in this study. Oral health status & the oral health control methods examined 3 times periodically for 2 weeks interval. And the obtained results were analyzed and compared. 1. At 1st oral survey, the longer periods the patients had been hospitalized, the higher score of plaque index, calculus index, gingival index & periodontal index had presented comparatively. 2. As a longitudinal studies for patients, it was estimated that plaque index, calculus index, gingival index were changed with high score tendencies gradually. 3. In Snyder test, the longer for non-ambulated were performed the higher degree of caries activity were estimated more of less. 4. It was represented that daily tooth brushing frequency was reduced gradually in long term hospitalized patients otherwise there was no significance in statistically. 5. It was estimated that more frequencies be found in patients hospitalized in K hospital in which located at central region of Seoul city than those of in J hospital located up town region. So it would be represented that the less plaque index, claculus index & gingival index were founded at the patients hospitalized in K hospital. 6. It was recommended that special oral health program should be needed and special dental manpower might be required to promote dental health levels for long termed medically hospitalized patients.

미세 물 흐름 측정장치의 개발과 상아세관액의 수력학에의 응용

이인복,김민호,김선영,장주혜,조병훈,손호현,백승호 大韓齒科保存學會 2008 Restorative Dentistry & Endodontics Vol.33 No.2

본 연구의 목적은 나노리터 수준의 물 흐름을 계측할 수 있는 장치를 개발하고, 상아질의 물 투과성을 측정하여 치아과민증 치료제와 상아질 접착제의 상아세관 밀폐효과를 알아보고자 하였다. 본 연구에서 제작한 미세흐름 측정장치는 첫째, 물의 흐름을 감지하는 모세관과 광 센서부, 둘째 물의 흐름을 추적하는 서보모터와 구동부, 셋째, 모터의 회전을 측정하여 물의 이동량으로 변화하는 엔코더와 컴퓨터 기록장치 등 세 부분으로 구성되어 잇다. 본 장비를 이용하여 교합면이 절단되어 노출된 상아질의 물 투과도와 치아과민증 치료제인 BisBlock과 자가부식형 상아질접착제인 Clearfil SE bond의 상아질 밀폐효과를 측정하여 다음과 같은 결과를 얻었다. 1. 나노리터 수준의 물 흐름을 측정할 수 있는 장치를 제작하였고, 이를 이용하여 상아질의 물 투과도를 측정할 수 있었다. 2. 삭제 후 노출 연마된 상아질은 0.84 - 15.2 nL/s의 물 투과도를 보였고 Oxalate 제재인 BisBlock 이나 자가부식형 접착제 Clearfil SE bond 적용시 투과도가 39.8 - 89.6% 감소하였다. This study was aimed to develop an instrument for real-time measurement of fluid conductance and to investigate the hydrodynamics of dentinal fluid. The instrument consisted of three parts: (1) a glass capillary and a photo sensor for detection of fluid movement, (2) a servo-motor, a lead screwand a ball nut for tracking of fluid movement, (3) a rotary encoder and software for data processing. To observe the blocking effect of dentinal fluid movement, oxalate gel and self-etch adhesive agent were used. BisBlock (Bisco) and Clearfil SE Bond (Kuraray) were applied to the occlusal dentin surface of extracted human teeth. Using this new device, the fluid movement was measured and compared between before and after each agent was applied. The instrument was able to measure dentinal fluid movement with a high resolution (0.196 nL) and the flow occurred with a rate of 0.84 to 15.2 nL/s before treatment. After BisBlock or Clearfil SE Bond was used, the fluid movement was decreased by 39.8 to 89.6%.

L-N-Benzylaspartic acid의 선택적 에스테르화 반응

이채호,김일광,박승화,이영행,정봉영 圓光大學校 基礎自然科學硏究所 1987 基礎科學硏究誌 Vol.6 No.1

Selective esterification and synthesis of L-N-benzylaspartic acid from L-aspartic acid are described. L-Aspartic acid was transformed into dibenzyl L-asparate p-toluenesulfonate, which was treated with sodium bicarbonate to afford dibenazyl L-asparate. Formation of Schiff base of dibenayl ester with benzaldehyde and subsequent hydrogenation-dehydrogenation of the Schiff base produced L-N-benaylaspartic acid. L-N-Benaylaspartic adcid was transformed into L-N-benzylaspartic anhydride hydrogen bromide, which was treated with methyl alcohol and benzyl alcohol to afford a-methyl and a-benzyl L-N-benzylaspartate and L-N-benaylaspartic acid was transformed into L-N-benaylaspartic acid copper(Ⅱ) salt, which was treated with N,N,N,N-tetramethylguanidine and benzyl bromide to afford β-benzylaspartate

Flowable 복합레진의 slumping 경향과 유변학적 성질

이인복,민선홍,김선영,조병훈,백승호 대한치과보존학회 2009 Restorative Dentistry & Endodontics Vol.34 No.2

본 연구의 목적은 flowable 복합레진의 조작성과 큰 연관이 있는 slumping 경향을 측정하는 방법을 제시하고 이와 관련이 있는 복합레진의 유변학적 특성을 고찰하였다. 5 종의 flowable 복합레진 (Aelitefil Flow:AF. Filtek flow: FF. DenFil flow: DF, Tetric flow:TF and Revolution: RV)이 사용되였다. 주사기에 담긴 일정량의 복합레진을 일정한 속도로 가압할 수 있는 장치를 이용하여 슬라이드글라스 위에 사출한 후 25℃의 실온에서 10초 동안 slumping이 일어나도록 방치 한 후 광중합 하였다. 복합레진의 slumping 경향을 평가하기 위해 원뿔 형 혹은 돔형으로 경화된 시편의 aspect, ratio (밑면의 지름에 대한 높이의 비)를 구하였다. Slumping 경향과 복합레진의 유변학적 성질과의 관련성을 알아보기 위해 Rheometer를 사용하du 각진동수 ω=0.1-100 rad/s의 범위에서 동적진동전단시험을 시행하여 복합레진의 복소점도를 구하였다. 복합레진의 slumping 경향을 비교하기 위해 일원분산분석 및 Turkey's post test를 시행하였고 (α<0.05) 복소점도와 aspect ratio 사이의 관련성을 알아보기 위해 회귀분석을 시행하였다. 결과는 다음과 같다. 1 Slumping 후 aspect ratio를 측정하여 비교한 flowable 복합레진의 slumping 경향은 제품에 따라 큰 차이를 보였다 (AF <FF < DP< TF <RV, P<0.05) 2. Flowable 복합레진은 전단률이 증가함에 따라 점도는 감소하는 pseudoplasticity를 보였고 그 경향은 AF가 가장 컸고 RV가 가장 낮았다. 3. Slumping 저항성은 복소점도가 증가함에 따라 증가하였다. 4 Aspect ratio에 바탕을 둔 slumping 경향의 측정방법은 임상에서 flowable 복합레진의 선택과 새로 개발된 재료의 평가에 유용할 것으로 사료된다. The aim of this study was to develop a method for measuring the slumping resistance of flowable resin composites and to evaluate the efficacy using rheological methodology. Five commercial flowable composites (Aelitefil flow:AF. Filtek flow:FF .DenFil flow:DF. Tetri flow:TF and Revolution:RV) were used. Same volume of composites in a syringe was extruded on a glass slide using a custom-made loading device. The resin composites were allowed to slump for 10 seconds at 25℃ and light cured. The aspect ratio (height/diameter) of cone or dome shaped specimen was measured for estimating the slumping tendency of composites. The complex viscosity of each composite was measured by a dynamic oscillatory shear test as a function of angular frequency using a rheometer. To compare the slumping tendency of composites one way-AN0VA and Turkey's post hoc test was performed for thc aspect ratio at 95% confidence Ievel. Regression analysis was performed to investigate the relationship between the complex viscosity and the aspect ratio. The results were as follows. 1. Slumping tendencv based on the aspect ratio varied among the five materials (AF <FF < DF<TF<RV). 2. Flowable composites exhibited pseudoplasticity in which the complex viscosity decreased with increasing frequency (shear rate). AF was the most significant. RV the least. 3. The slumping tendency was strongly related with the complex viscosity. Slumping resistance increased with increasing the complex viscosity. The slumping tendency could be quantified by measuring the aspect ratio of slumped flowable composites. This method may be applicable to evaluate the clinical handling characteristics of flowable composites.

중간세공탄소를 담체로 사용한 직접메탄을 연료전지용 Pt/C 촉매제조

하승백,김현수,최재식,정원섭,이호인 한국공업화학회 2003 응용화학 Vol.7 No.2

For the direct methanol fuel cell, the expensive cost of Pt is one of the most important factors. In this study, various kinds of support were synthesized and chosen for highly dispersed catalysts which need less amount of Pt and show higher activity. A mesoporous carbon was selected as a support which has 5 times larger specific surface area than Vulcan XC-72, a commercial support. Such a large surface area gave an advantage in the dispersion of Pt, but a disadvantage in electric conductivity which could be solved by increasing the carbonizaton temperature in the preparation of mesoporous carbon. These prepared mesoporous carbons were used as supports of Pt. Among the catalysts, the catalyst using mesoporous carbon carbonized at 1000 ℃ showed better activity than the catalyst using Vulcan XC-72 as a support showing the best activity. From the XRD analysis, the activity was proportional to the dispersion of Pt.

[논문]감천댐 건설에 따른 기상변화 연구

이화운,정우식,이귀옥,임헌호,백승주 부산대학교 환경문제연구소 2004 環境硏究報 Vol.22 No.-

In order to investigate the variation of meteological factors induced by construction of dam, the prediction model, WQRRS, is used. As a result, the effect of Dam construction showed that the amount of evaporation increases because of broad water surface area. Therefore, nighttime relative humidity is raised, and annual foggy days are increased more than 7days and sunshine hours are decreased.

직접메탄을 연료전지용 귀금속 산화극 대체촉매의 개발

최재식,윤봉국,하승백,정원섭,이호인 한국공업화학회 2003 응용화학 Vol.7 No.2

Direct Methanol Fuel Cell (DMFC) is based on the technology of Polymer Electrolyte Membrane Fuel Cell. DMFC has several features of environmentally benign generation of electricity and high mobility for portable electronics etc., but its main problem to overcome for commercialization is the high cost of noble metal catalysts. In this study, it was found that the Pt/C catalyst supported on carbon nano fiber had the highest catalytic activity among the catalysts supported on several carbons. The newly developed Pt/C alternative catalyst had higher catalytic activity for methanol oxidation than the Pt/C catalyst supported on Vulcan XC-72.

치은연하 파절로 치조골 소실을 동반한 상악측절치에서 orthodontic extrusive remodeling후 임플란트 식립을 통한 심미수복 : 증례보고

황수연,손원준,한영철,배광식,백승호,이우철,금기연 大韓齒科保存學會 2008 Restorative Dentistry & Endodontics Vol.33 No.1

심미적으로 중요한 전치부에서 단일 치아 임플란트를 이용한 보철수복은 임상의에게 새로운 도전과제 중의 하나가 되었다. 그러나 전치부에서 single-unit implant는 식립할 부위의 치조골 상태가 양호해야 하는데 치은연하 파절로 인해 치아 주위에 골 손실이 있는 경우 immediate implant는 심미적으로 문제를 야기할 수 있다. 따라서 본 증례는 "orthodontic extrusive remodeling"을 통해 파절치와 주위 조직을 교정적으로 정출시켜 임플란트 식립을 위한 연조직과 경조직을 증대시킨 후 임플란트 식립을 통해 상악측절치에서 성공적인 심미수복을 이룬 증례에 관한 것이다. The treatment of esthetic areas with single-tooth implants represents a new challenge for the clinician. In 1993, a modification of the forced eruption technique, called "orthodontic extrusive remodelling" was proposed as a way to augment both soft- and hard-tissue profiles at potential implant sites. This case report describes augmentation of the coronal soft and hard tissues around a fractured maxillary lateral incisor associated with alveolar bone loss, which was achieved by forced orthodontic extrusion before implant placement. Through these procedures we could reconstruct esthetics and function in a hopeless tooth diagnosed with subgingival root fracture by trauma.