CaO-$C_2 H_5 OH$-$CO_2$계의 기.액반응에 의한 비정질 탄산칼슘의 합성 및 결정구조

임재석,임굉,Im, Jae-Seok,Im, Goeng 배재대학교 공학연구소 2004 공학논문집 Vol.6 No.1

CaO의 첨가량에 따라 $CO_2$가스를 불어넣고 반응시간 변화에 따라 용매로 $C_2 H_5 OH$을 사용하여 에틸렌글리콜을 첨가한 CaO-$C_2 H_5 OH$-$CO_2$계의 기.액반응으로부터 비정질 $CaCO_3$의 합성과 결정구조를 전기전도도, X-선회절 및 주사전자현미경으로 조사하였다. 이 반응에서 900ml의 $C_2 H_5 OH$에 에틸렌글리콜 100ml를 첨가하고 CaO의 양을 10~40g으로 하여 $CO_2$가스를 1$\ell$/min의 유속으로 흡입시켜 얻은 합성분말의 겔형 물질을 신속히 여과, 감압하의 $60^{\circ}C$에서 건조하여 1${\mu}m$이하의 구형 vaterite상과 무정형인 비정질 $CaCO_3$을 얻었다. 그리고 비정질 $CaCO_3$의 일부는 중간생성물로서 연쇄형 calcite로 변화하는 것을 알 수 있었고 침강성 $CaCO_3$의 생성보다 먼저 초기 반응생성물은 비정질 $CaCO_3$이었고 이 경우 생성역역은 pH 7-9의 범위로 상당한 영향을 준다. 또한 비정질 $CaCO_3$은 용액 속에서 불안정하여 용해반응으로 인해서 결국 calcite로 결정화한다. 특히 비정질 $CaCO_3$은 CaO-$C_2 H_5 OH$-$CO_2$계의 반응에 의해서 침강되어 생성되거나 또는 gel상으로 된다. The synthesis and crystal structure of amorphous calcium carbonate obtained from gas-liquid reaction of CaO-$C_2 H_5 OH$-$CO_2$ system according to change of added amount of calcium oxide by blowing $CO_2$ gas and reaction time using ethanol and ethylene glycol were investigated by electric conductivity, X-ray diffraction, and scanning electron microscope. The powdery or gelatinous phases were prepared by passing $CO_2$ gas at a flow rate of 1$\ell$/min into the suspensions containing 10~40g of CaO in mixing solutions 900ml of $C_2 H_5 OH$- and 100ml of ethylene glycol. By rapid filtration and drying the both phases at $60^{\circ}C$ under reduced pressure, the phases converted to the spherical vaterite and amorphous phase. The stable phase of amorphous calcium carbonate(ACC) was formed in the region pH 7-9 but the formation regions of amorphous phase were remarkably affected by pH in the mother liquor. It seems that a part of ACC changed into chain calcite as an intermediate products. The initial reactants prior to the formation of precipitated calcium carbonate is ACC. And ACC is unstable in the aqueous solution and crystallizes finally to calcite by the through-solution reaction. Especially ACC was produced or gelatinous phase which precipitated from the reaction of CaO-$C_2 H_5 OH$-$CO_2$ system.

Ca($OH_2$)-$H_2 O$-$CO_2$계의 기액반응으로부터 비정질 탄산칼슘의 합성 및 결정화

임재석,김가연,임굉,Im, Jae-Seok,Kim, Ga-Yeon,Im, Goeng 배재대학교 공학연구소 2004 공학논문집 Vol.5 No.1

수산화칼슘현탁액과 탄산가스를 출발물질로 15~$50^{\circ}C$의 온도에서 기액반응으로 비정질 탄산칼슘($CaCO_3$.$nH_2 O$)의 생성과정을 전기저도도의 연속측정법, X-선회절법 및 투과전자현미경법을 이용하여 조사한 결과, 반응초기생성물은 비정질 탄산칼슘으로 반응현탁액의 전기전도도는 비정질 탄산칼슘의 생성 중 크게 강하하고 있으며, 이것은 수산화칼슘의 입자표면이 비정질 탄산칼슘미립자로 뒤덮여 용해를 방해받는 것과 비정질 탄산칼슘이 용액 속에서 불안정하여 즉시 용해한 다음 석출하여 칼사이트로 전이되어 미세한 침강성 탄산칼슘이 나란히 결합한 연쇄형 칼사이트가 생성된다. 비정질 탄산칼슘이 연쇄형 칼사이트로 변화하는 동안 현탁액의 전기전도도는 급격히 회복되고 이 과정에서 고농도 수산화칼슘현탁액의 외관점도가 상승한다. 이것은 연쇄형 칼사이트의 뒤얽힘에 의한 것이며, 다시 전기전도도의 1회 회복단계 이후에는 미반응 수산화칼슘에 의하여 비정질 탄산칼슘이 생성이 소멸되어 칼사이트의 성장반응이 이루어지고 pH가 9.5이하에서 연쇄형 칼사이트는 결합부분이 먼저 용해하여 결정질 탄산칼슘으로 분리생성된다. 비정질 탄산칼슘의 생성 및 합성온도의 영역은 전기전도도법에서 $15^{\circ}C$일 때 1차 강하단계(a-단계)에서 가장 적합하다. The synthesis and crystallization of amorphous calcium carbonate($CaCO_3$.$nH_2 O$) obtained from gas-liquid reaction between aqueous solution of calcium hydroxide and carbon dioxide at 15~$50^{\circ}C$ are investigated by electrical conductometry, XRD and TEM. The results are as follows: The initial reaction products prior to the formation of precipitated calcium carbonate is amorphous calcium carbonate. The electrical conductivity values in the slurry are decreased during the formation of amorphous calcium carbonate which covers particle surface of calcium hydroxide and retard the dissolution of calcium hydroxide into the solution. that amorphous calcium carbonate is unstable in the aqueous solution and crystallizes finally to calcite by the through-solution reaction. While amorphous calcium carbonate crystallizes into chain-like calcite, the conductivity values are recovered rapidly and the apparent viscosity of slurry containing higher concentration of calcium hydroxide increase. At below pH 9.5, chain-like calcite separates into individual particles to form precipitated calcium carbonate. The formation and synthetic temperature range of amorphous calcium carbonate is most suitable a primary decreasing step(a-step) at $15^{\circ}C$ in the electrical conductometry.

한국 성인에서 흡연과 대사증후군의 관련성

임재석(Jae Seok Im),김나래(Na Rae Kim),오정은(Jung Eun Oh),홍성호(Sung Ho Hong),조주연(Choo Yon Cho),조용진(Yong Jin Cho),유병욱(Byung Wook Yoo),신경숙(Kyung Suk Shin),조현(Hyun Joe),신황식(Hwang Sik Shin),손두용(Doo Yong Son) 대한임상노인의학회 2018 대한임상노인의학회지 Vol.19 No.1

Background: Several studies suggest that smoking is a risk factor of metabolic syndrome. The objective of this study is to evaluate the association between smoking status and metabolic syndrome among Korean adults. Methods: We assessed 4349 participants aged 19 years and older from the Korean National Health and Nutritional Examination Survey 2013. Smoking statuses were collected from self-reported questionnaires. Subjects were divided into three categories: non-smokers, former smokers, and current smokers. The diagnosis of metabolic syndrome was made using criteria modified NCEP-ATP III. Logistic regression analysis was used to calculate odds ratios between smoking status and metabolic syndrome. Results: The overall prevalence of metabolic syndrome was 27.8% and former smokers had the highest prevalence of metabolic syndrome at 30.7%. After adjustment for age, sex, alcohol consumption, physical activity and body mass index, the odds ratio for high density lipoprotein cholesterol disorder, triglyceride disorder, abdominal obesity in current smokers was 1.25 (95% CI, 1.02~1.54), 1.83 (95% CI, 1.48~2.26), and 1.35 (95% CI, 1.00~1.81) compared with non-smokers, respectively. For metabolic syndrome, the odds ratio in current smokers was 1.30 (95% CI, 1.02~1.68) compared with non-smokers. Conclusion: Current smokers showed increased risk for metabolic syndrome. Smoking status was associated with increased risk of metabolic syndrome in Korean adults.

서미스터용 Mn-Co-Ni-Fe계 산화물의 조성에 따른 전기저항특성

김영민,임재석,임굉,Kim, Yeong-Min,Im, Jae-Seok,Im, Goeng 배재대학교 공학연구소 2004 공학논문집 Vol.5 No.1

Mn-Co-Ni 3성분계에 Fe의 첨가량을 변화시켜 따른 산화물 서미스터소결체(Mn-Co-Ni-Fe oxide)를 소성온도 1200~$1400^{\circ}C$에서 제조하여 전기저항특성을 조사한 결과, 결정상은 단일입방정 스피넬형 결정구조였고, 소성온도에 따른 전기전도도는 $1300^{\circ}C$에서 4시간 소결한 시미스터가 가장 높았다. 대체로 F-2를 제외하고는 Fe의 첨가량이 증가할 때 비저항은 증가하고 상대적으로 전기전도도는 감소한다. 특히 F-2의 조성에 있어서는 전기전도도가 1.4${\times}$$10^-3$${\ textohm}cm로 높았고 상대적으로 B정수는 2906K로 낮았다. The properties of electrical resistance of Mn-Co-Ni-Fe oxide-based thermistor with various Fe contents in sintering process at $1200^{\circ}$ to $1400^{\circ}C$ for 4 hours in air atmosphere for fabricating thermistor materials were investigated. The results were as follows: all samples showed single cubic spinel crystal structures in all region. The electrical conductivity is the highest thermistor sintered at $1300^{\circ}C$ for 4 hours. In general when the Fe content is increased except F-2, the resistivity increases and relatively the conductivity decreases. Particularly F-2 composition exhibited the highest electrical conductivity (1.4${\times}$$10^-3$${\textohm}cm) and relatively low B constant(2906K)

군날개절제술 후 발생한 공막연화증에서 무세포성 동종진피이식술

송해윤,임재석,곽주영.Hae Yoon Song. M.D.. Jae Seok Im. M.D.. Ju Young Kwak. M.D. 대한안과학회 2008 대한안과학회지 Vol.49 No.10

Purpose: To report two cases of successful acellular dermal allograft transplantation for scleromalacia following pterygium excision. Case summary: A 72-year-old female patient developed scleromalacia on the nasal side of the right eye, and a 79-year-old female patient developed scleromalacia with inflammation on the nasal side of the left eye. They had previous histories of pterigia removal on the sites of scleromalacia. Acellular dermal allograft (AlloDerm<sup>®, Lifecell, NJ, USA) transplantations were done. After the operations, inflammation and pain ameliorated and the grafts survived without any particular complications. Conclusions: In treating scleromalacia, the transplantation of acellular dermal allografts produced relatively satisfactory results without undesirable problems commonly encountered when using conventional materials. J Korean Ophthalmol Soc 2008;49(10):1685-1689

각막궤양천공에서 익상편을 이용한 자가결막이식술 1예

정상문,임재석,박동.Sang Moon Jeoung. M.D.. Jae Seok Im. M.D.. Dong Park. M.D. 대한안과학회 2008 대한안과학회지 Vol.49 No.12

Purpose: To report a case of conjunctival autotransplantation using the conjunctival flap of the pterygium for thetreatment corneal ulcer perforation. Case summary: A 72-year-old woman was referred to our hospital because her left eye had a corneal ulcer due topine needle trauma, and she did not respond to the initial therapy in a private clinic for 1 week. We first applied topical and systemic antibiotics. However, the lesion did not subside, and necrosis progressed in the stroma at the center of the cornea. On day 6 of admission, perforation was found at the center of the cornea, and we excised the necrotic tissue and performed bilateral pedicle conjunctival flap transposition. After the operation, an ischemic change was observed, and in the fourth week perforation occured at the center of the transplanted conjunctival flap. Because we considered it difficult to perform the transplantation of a conjunctival flap in the left eye, we performed autotransplantation on the corneal perforation in the left eye using conjunctival flap obtained through a pterygium excision in the right eye. After the operation, vascular ingrowth started from the edge of the flap, and there were no symptoms of inflammation, shrinkage, or necrosis of the flap. During the follow-up observation, the flap survived well without necrosis.