합성 Hydroxyapatite/Polyacrylic Acid 균질복합체의 제조 및 특성

이석기,이형동,신효순,이병교,Lee, Suk-Kee,Lee, Hyung-Dong,Shin, Hyo-Soon,Lee, Byung-Kyo 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.11

$Ca(NO_3)_2{\cdot}4H_2O$와 $(NH_4)_2HPO_4$를 사용하여 습식침전법으로 수산화아파타이트(HAp) 분말을 합성하고, 합성된 HAp와 폴리아크릴산(PAA)을 혼합하여 균질의 복합체 4종을 제조하였다. 합성 HAp는 ICP 분석으로 Ca/P비를 정량하였고, HAp/PAA 복합체는 TGA로 열적 성질을 조사하였다. pH 11 및 $60{\circ}C$에서 합성된 HAp의 결정성이 가장 우수하였고, Ca/P비는 1.35~1.49의 범위로 정량되어 Ca 결손의 HAp를 얻었다. HAp/PAA 복합체에서 PAA의 양이 증가함에 따라 비표면적이 증가하였다. 또한 HA/PAa 균질복합체의 $800{\circ}C$에서 무게감량은 3.5~9.6%의 범위로 감소하여 바인더인 PAA가 분해되는 것을 알 수 있었다. HAp/PAA 복합체의 FT-IR 분석결과, HAp의 $Ca^{2+}$ 이온과 PAA의 카르복실기 사이에서 이온결합이 형성되는 사실을 확인할 수 있었다. Hydroxyapatite(HAp) powders were synthesized by wet-precipitation precess using $Ca(NO_3)_2{\cdot}4H_2O$ and $(NH_4)_2HPO_4$ and homogeneous composites of four type were prepared by mixing of synthetic HAp and Polyacrylic Acid(PAA). Ca/P ratio of synthetic HAps was determined using ICP analysis and the thermal property of HAp/PAA composites were investigated by TGA. Good crystalline HAp was obtained at pH 11 and $60{\circ}C$. The ratio of Ca/P in synthetic HAps was quantified in a range of 1.35~1.49, from which Ca-deficient HAp was obtained. The specific surface area of HAp/PAA composite increased with increasing the content of PAA and the weight loss of HAp/PAA composite at $800{\circ}C$ decreased in a range of 3.5~9.6% due to the degradation of PAA binder. From FT-IR analysis of HAp/PAA composite, it was confirmed that the ionic bond between .$Ca^{2+}$ ion of HAp and carboxyl group of PAA was formed.

신생아 기흉의 임상적 고찰

이석기,임진수,최형호,Lee, Seok-Gi,Im, Jin-Su,Choe, Hyeong-Ho 대한흉부심장혈관외과학회 1995 Journal of Chest Surgery (J Chest Surg) Vol.28 No.12

From 1991 to 1994, we experienced 24 cases of neonatal pneumothorax who were admitted to the Neonatal Intensive Care Unit[NICU , Chosun University Hospital. The Following results were obtained.1 The incidence of neonatal pneumothorax was 0.70%, and there were 8 spontaneous pneumothoraces and 16 secondary pneumothoraces. 2 The clinical manifestation of neonatal pneumothorax was as followed. Male infant was dominant[M:F=2:1 , the onset was within 24 hours in the majority[83% , and the right side[62% was more frequent than the left side. The gestation duration and birth weight show no correlation with underlying neonatal pneumothorax. The pulmonary diseases were meconium aspiration syndrome and hyaline membrane disease, and the incidence of those was 58%. Meconium aspiration syndrome occurred earlier than hyaline membrane disease. Symptoms and signs were tachypnea[46% , cyanosis[21% , irritability[13% , chest retraction[8% and apnea[8% .3 The treatments performed were oxygen therapy[17% , thoracentesis[4% and closed thoracostomy with underwater seal drainage[79% . The Mean duration of air leakage was 11.7 hours, and the mean drainage time was 4.35$\pm$1.3day. 4 The overall hospital mortality was 33%, and the rate of complication was 46%. The complications were metabolic acidosis, atelectasis, pleural effusion, pulmonary hemorrhage and pneumonia. We concluded that the prognosis was related to the underlying pulmonary disease.

SR 바탕보정법과 $D_2$ 바탕보정법에 의한 혈액 중 Pb 분석

이석기,김풍작,Lee, Seokki,Kim, Poongzag 한국분석과학회 1994 분석과학 Vol.7 No.4

For the analysis of the relatively volatile lead in blood by GFAAS(graphite furnace atomic absorption spectrophotometer), one can not raise the ashing temperature beyond certain degree due to the elevation of the baseline. Previous investigations showed that background is stabilized when the ashing temperature is raised to $700^{\circ}C$ using a matrix modifier. In this study, same result was obtained at the ashing temperature of around $550^{\circ}C$ even when the matrix modifier is not used and only Triton X-100 is used as a diluent, on an instrument which is equipped with both temperature and current controller(Shimadzu, AA-6501S) and thus the temperature control is fast and accurate. Background correction methods of $D_2$ arc and SR(self reversal) were reviewed. The results show that the absorbance is higher for the $D_2$ arc method, but the background correction is higher for the SR method. GFAAS(graphite furnace atomic absorption spectrophotometer)를 이용하여 혈액 중 납을 분석할 때, 납은 비교적 휘발성 원소인 관계로 바탕선이 높아지므로 희화 온도를 일정 온도 이상으로 높일 수 없었다. 그래서 종래에는 매트릭스 변형제를 사용하여 희화 온도를 $700^{\circ}C$까지 올려서 희화시켜야 바탕선이 안정되었다. 본 연구에서는 광온도 및 전류 제어 장치가 부착된 기기(Shimadzu, AA-6501S)를 사용하여 온도조절을 단시간에 정확히 함으로써 매트릭스 변형제를 사용하지 않고 Triton X-100으로만 희석하여 분석해도 희화 온도 $550^{\circ}C$ 부근에서 바탕선이 안정됨을 알았다. 또한 자동 바탕 보정 장치인 $D_2$ arc형과 SR(self reversal)법을 비교해 본 결과, 같은 농도에서의 흡광도는 $D_2$ arc형이 높았으나 BGC(background correction)값은 SR법이 높음을 알았다.

차량 시뮬레이터를 이용한 안개 대응 시스템 효과 분석

이석기,정준화,Lee,Suk Ki,Jeong,Jun Hwa 한국방재학회 2012 한국방재학회논문집 Vol.12 No.1

도로상의 안개는 대체로 시정거리를 변화시키며 도로 운전자에게 안전에 영향을 준다. 안개 지역 도로에서 연쇄추돌 사고는 주로 후미 추돌 사고이며 사고의 원인은 시거불량과 주행 차량들간의 속도편차 때문이며 주행차량들이 안개시 적절한 주행속도와 차간거리를 유지하는 것이 무엇보다 중요하다. 본 연구에서는 안개 발생시 안전성을 확보할 수 있는 안개 대응 시스템에 대한 설치 효과를 알아보기 위하여 차량 시뮬레이터를 이용하였다. 차량 시뮬레이터 실험을 위한 가상도로는 왕복 2차로 구간인 일반국도 37호선(문산~적성) 눌노천교 주변 1 km 구간으로 운전자 경고등을 25 m와 30 m 간격으로 변경시켰다. 안개 상황은 짙은 안개(시정거리 30 m)와 옅은 안개(시정거리 80 m)로 설정하였다. 피험자는 20대~60대의 성인 남녀 31명을 대상으로 본 실험에 앞서 시뮬레이터에 적응할 수 있는 충분한 연습주행과 사전정보를 제공한 후 주행실험을 한 후 설문조사를 실시하였다. In a foggy day, visible distances depend greatly on the ever-changing concentration of fog. Most of chained rear-end collisions in a foggy day are caused by the significant differences in speeds between vehicles. Then, it is important to minimize the collisions in fog. This study is to estimate the effects of FDWS on drivers` safety behaviors by using a vehicle simulator and a questionnaire survey. A roadway section 1 km long with bidirectional 2 lanes was chosen for the estimation efforts. The test segment was from the Munsan to the Jeokseong county in National Highway 37. Scenarios associated with fog were set as heavy fog. Also, the distance between driver warning lamps was considered by 25 m and 30 m, respectively. The experiment conducted in this study employed the total of 31 adults who were randomly selected from 20- to 60-year old. Before performing the experiment, each subject had enough times to be familiar with the vehicle simulator and was instructed by the guideline of the experiment. After performing the main test, a questionnaire survey was undertaken for each subject.

쌀 첨가비율에 따른 맥주의 품질 특성 평가

이석기,박지영,박혜영,최혜선,조동화,오세관,김현주,Lee, Seuk Ki,Park, Ji-Young,Park, Hye-Young,Choi, Hye Sun,Cho, Donghwa,Oh, Sea-Kwan,Kim, Hyun-Joo 한국식품저장유통학회 2017 한국식품저장유통학회지 Vol.24 No.6

본 연구는 쌀맥주에 적합한 쌀 첨가비율을 선정하기 위해 연질미인 한가루 품종을 이용하여 첨가비율에 따라 맥주를 제조하고 품질특성을 비교분석하였다. 쌀 첨가비율별로 제조한 맥주의 알코올 함량을 측정한 결과 3.93-4.40%로 나타났고, 쌀 첨가비율에 따라 가용성 고형분은 증가하는 것으로 확인되었다. pH는 4.32-4.60의 범위로 나타났으며, 쌀 첨가비율에 따른 유의적인 차이는 없었다. 쌀 첨가비율에 따라 맥주의 산도 및 아미노산도가 낮아지는 경향을 보였으며, 쌀 첨가비율이 증가할수록 명도는 증가한 반면 적색도 및 황색도는 감소하는 경향을 보였다. 특히 쌀 첨가 비율이 높을수록 쓴맛의 강도는 감소하는 것으로 나타났다. 이상의 결과를 종합하여 볼 때, 맥주를 가공하는 데에 있어 쌀의 첨가비율이 증가할수록 쓴맛이 감소되고 색택이 개선되는 등 품질 개선의 효과를 얻었다. 본 연구결과는 쌀맥주를 대량으로 제조하는 데 있어서 품질이 우수한 최적 비율을 선정하는데 기초자료로 활용될 수 있을 것이라고 판단된다. In this study the effect of rice addition on the quality of beer was investigated. Pilot-scale brews were performed with addition ratios of 10, 20, 30, and 40% of brown rice (Oryza sativa L. cv. Hangaru) which were compared with 100% malt beer and commercial beers in terms of quality. Alcohol content of beer was between 3.93 to 4.40%. The total sugar content increased when the rice percent was increased. The pH range of beer were 4.32 and 4.60, which were no significant differences found among by the rate of rice added. Total acidity and amino-acidity decreased corresponding to increasing percent of rice, on the other hand, lightness of beer was increased the increase in percent of rice, while redness and yellowness of beer were decreased. The study demonstrated that the increases of rice addition in beer provided some positive effects on beer quality by decreasing bitterness where as improving beer color.

「조합업무안내 」-편리하고 신속한 인터넷보증서 발급서비스(2)

이석기,Lee, Seok-Gi 대한기계설비건설협회 2004 기계설비 Vol.167 No.-

여러가지 물혼합용매 속에서 p-Chlorobenzyl Chloride의 가용매분해

이석기,이억석,Lee, Suk-Kee,Lee, Euk-Suk 대한화학회 1971 대한화학회지 Vol.15 No.4

The thermodynamic parameters for the solvolysis of the p-chlorobenzyl chloride taking place in the various aqueous mixtures were determined. From the application of these data to the formula ${\delta}_M{\Delta}H^{\neq}=a'Y+b{\delta}_M{\Delta}S^{\neq}$ the following conclusion was obtained: That the substrate constant a' differs in different aqueous solvent was found, and using each a' value the solvolysis mechanism of p-chlorobenzyl chloride in each aqueous mixture can be determined.

토끼 흉부 대동맥 절편의 전기자극에 대한 수축 및 이완반응

이석기,최형호,이종운,Lee, Seok-Gi,Choe, Hyeong-Ho,Lee, Jong-Un 대한흉부심장혈관외과학회 1995 Journal of Chest Surgery (J Chest Surg) Vol.28 No.8

The present study was aimed at investigating possible transmitter mechanisms in the endothelial cell layer in regulating the tone of the vascular smooth muscle. The thoracic aorta was isolated from the anesthetized male white rabbits and its helical strips were prepared. Electrical field stimulation was delivered to platinum wire electrodes positioned parallel to the vessel segment preconstricted with phenylephrine [3.5x10-6 mol/L at a distance of 1.5-2.0 mm. The electrical stimulation [70 V, 5 msec, 0.5-200 Hz caused either relaxation only [34% or a biphasic response [prolonged relaxation following a weak and transient contraction, 66% . The relaxation response was frequency- dependent, and at 200 Hz a complete relaxation was noted. Mechanical rubbing of the endothelial layer abolished or greatly attenuated the relaxation. The relaxation was also markedly attenuated in the presence of NG-nitro- L-arginine methyl ester [10-3mol/L or procaine hydrochloride [3.5x10-4mol/L . Tetrodotoxin,guanethidine, atropine or indomethacin failed to block or enhance the relaxation response to electrical field stimulation. It is concluded that the vascular endothelium in the aorta contains diffusible substances that regulates the function of the smooth muscle layer, in which relaxation is more prominent than contraction. Their release by the electrical stimualtion in vitro may not involve classic neuronal transmitter release mechanisms or metabolism of arachidonic acids by cyclooxygenase. The release of the relaxing agents may require an increase in cytosolic calcium level. The chemical nature of the relaxant may be, to a large extent, nitric oxide.

N,N' - 비스아크릴아미드 유도체의 합성

이석기,김우식 ( Suk Kee Lee,Woo Sik Kim ) 한국공업화학회 1997 공업화학 Vol.8 No.6

염화아크릴로일과 여러 종류의 디아민을 트리에틸아민 존재하에서 Schotten-Baumann 반응에 의해 N,N`-비스아크릴아미드 유도체 4종을 합성하였고, IR, ^1H-NMR, 원소분석을 통해 구조를 확인하였다. 합성한 N,N`-헥사메틸렌비스아크릴아미드 (HMBA)와 N,N`-도데카메틸렌비스아크릴아미드 (DMBA)의 수율은 56.0%와 70.4%로 디아민의 메틸렌기의 수가 증가할수록 높아졌다. 또한 N,N`-1,4-페닐렌비스아크릴아미드 (PhBA)와 N,N`-2,6-피리딘비스아크릴아미드(PyBA)의 수율은 각각 80.3% 및 83.1%로 N,N`-알킬렌비스아크릴아미드류보다 높게 나타났다. 합성한 N,N`-비스아크릴아미드 유도체는 여러 종류의 가교고분자 제조에 이용될 수 있다. Four kinds of N,N`-bisacrylamide derivatives were synthesized by Scotten-Baumann reaction from acryloyl chloride and several diamines in the presence of triethylamine, and their chemical structures were identified by IR, ^1H-NMR, and elemental analysis. The yields of the synthesized N,N`-hexamethylenebisacrylamide and N,N`-dodecamethylenebisacrylamide were 56.0% and 70.4%, respectively, and were increased with the increased number of methylene group in the dimines. The yields of the synthesized N,N`-1,4-phenylenebisacrylamide and N,N`-2,6-pyridinebisacrylamide were 80.3% and 83.1%, respectively, which were higher than those of the alkylenebisacrylamide derivatives. The synthesized N,N`-bisacrylamide derivatives can be used to prepare various crosslinked polymers.

성인에서 기종격증의 임상적 고찰

이석기,임진수,조남수,Lee, Seok-Gi,Im, Jin-Su,Jo, Nam-Su 대한흉부심장혈관외과학회 1995 Journal of Chest Surgery (J Chest Surg) Vol.28 No.12

Pneumomediastinum[Mediastinal emphysema is characterized by the presence of air in the mediastinum, and classified as spontaneous[occurring without obvious cause or secondary[caused by a trauma or artificial ventilation . To study the clinical evaluation of pneumomediastinum, data were obtained from 20 patients. The incidences of spontaneous pneumomedisastinum were 5 and those of secondary pneumomedistinum were 15 cases. The mean age was 21.2$\pm$3.4 years[$\pm$SD in spontaneous pneumomediastinum and 44.1$\pm$20.0 years[$\pm$SD in secondary pneumomediastinum. There were 16 male and 4 female patients. The common presenting compliants were retrosternal pain in 19 patients[95% , dyspnea in 12[60% , and hoarsness in 2[10% . The predisposing factors were asthma,excessive exercise and vomiting in spontaneous pneumomediastinum;trauma, artificial ventilation, tracheostomy, the rupture of trachea or esophagus in secondary pneumomediastinum. The physical findings were subcutaneous emphysema in 17 patients[85% , Hamman`s sign in 11 patients[55% and decreased cardiac dullness in 2 patients[10% . Spontaneous pneumomediastinums were managed conservatively, however, surigical procedures were needed in secondary pneumomediastinums. There was no recurrence, but one patinet died of tension pneumomedistinum. We concluded that spontaneous pneumomediastinum is uncommon, usually benign, and self-limited and secondary pneumomedistinum due to trauma or artificial ventilation is more increasing, and necessitates the early, aggressive intervention.