석분과 황토를 사용한 건자재 제품 개발 연구

성찬용,류능환,윤준노,김영익,임상혁 강원대학교 부설 석재복합신소재 제품연구센터 2003 석재연 논문집 Vol.8 No.-

본 연구는 석분과 황토를 사용한 건자재 제품을 개발하기 위하여 황토의 첨가량를 5종류, 석분의 첨가량을 3종류로 하여 총 16종류의 모르타르에 대하여 단위중량, 흡수율, 압축강도, 휨강도, 동탄성계수, 초음파진동속도, 중성화 깊이에 대하여 구명하였다. 단위중량, 압축강도, 휨강도, 동탄성계수 및 초음파진동속도는 황토와 석분의 사용량이 증가할수록 감소하는 경향을 나타내었고, 흡수율과 중성화 깊이는 증가하는 경향을 나타내었다. 주사전자현미경에 의한 관찰에서는 비활성황토의 사용량이 증가할수록 결정이 증가한 것으로 나타났다. 황토의 사용량은 강도적인 측면에서는 결합재량의 40%까지 사용이 가능하고, 흡수율 측면에서는 10%까지 사용이 가능하며, 건자재의 사용목적에 따라 황토의 사용량을 조절하는 것이 필요할 것으로 생각된다. The purpose of this study is to obtain the basic data for the development of construction materialproducts using stone dust and non-active Hwangto. The results of physical and mechanical properties were as follows. The unit weight, compressive and flexural strengths, dynamic modulus and ultrasonic pulse velocity are decreased with increase of the stone dust and Hwangto. The absorption ratio and neutralization depth are increased with increase of the stone dust and Hwangto. In the results of SEM analysis, the crystals are increased with increase of the non-active Hwangto. Accordingly, the Hwangto may be suitably used as a cement replacement material in the construction material products.

재생굵은골재를 사용한 콘크리트의 동결융해 특성

성찬용,윤준노,김영익,임상혁,정덕현 충남대학교 농업과학연구소 2003 농업과학연구 Vol.30 No.2

이 연구는 플라이 애시를 결합재 중량의 20%, 재생굵은골재를 천연쇄석굵은 골재의 0%, 25%, 50%, 75%, 100%를 치환하여 압축강도와 동결융해 특성을 구명하였으며, 이 연구를 통해 얻어진 결과를 요약하면 다음과 같다. 1. 재령 28일의 압축강도는 모든 배합비와 W/B 35%에서 400㎏f/㎠이상으로 나타나 고강도콘크리트에 이용될 수 있을 것으로 생각된다. 2. 중량감소율은 동결융해 300사이클에서 1%미만으로 나타났고, 표면박리와 같은 현상은 나타나지 않았으며, 재생골재의 대체율이 증가할수록 감소율은 증가하였다. 3. 초음파진동속도는 동결융해 300사이클에서 19~24%정도의 감소율을 나타내었으며, 재생골재의 대체율이 증가할수록 감소율은 증가하는 경향을 나타내었다. 4. 상대동탄성계슈는 재생골재의 대체율에 따라 60~72%의 범위로 나타내었으며, 재생골재 대체율이 증가할수록 감소하는 경향을 나타내었다. 5. 내구성지수는 모든 배합에서 60이상을 나타내었으나, 재생골재 대체율이 100%일때는 급격히 떨어지는 경향을 나타내었다. 6. 재생굵은골재를 사용한 콘크리트의 압축강도, 중량감소율, 초음파진동속도, 상대동탄성계수, 내구성지수 시험결과를 볼 때, 시험에 사용한 재생굵은 골재는 고강도콘크리트에 사용이 가능할 것으로 판단된다. This study was performed to examine the freezing and thawing properties of the high strength concrete using recycled coarse aggregate. The recycled coarse aggregate was replaced by 0%, 25%, 50%, 75% and 100% of natural crushed aggregate. The compressive strength of the concrete used recycled coarse aggregate was shown in more than 400kgf/㎤ at the curing age 28 days. The weight loss ratio by freezing and thawing was shown in less than 1% at all mix type. The pulse velocity and relative dynamic modulus were decreased with increasing the freezing and thawing cycles. Also, durability factor for the freezing and thawing were decreased with increasing the content of recycled coarse aggregate. But, recycled concrete replaced with recycled coarse aggregate 100% was shown in more than 60 by durability factor in freezing and thawing of 300cycles Accordingly, these recycled coarse aggregate can be used for high strength concrete.

Mini-implant를 이용한 III급 부정교합 환자의 협진 치료 : 문제중심의 교정치료

임동혁,김영신,조민아,김기성,양성은 대한치과교정학회 2007 대한치과교정학회지 Vol.37 No.4

LCD산업의 성과분석과 리더쉽 유지가능성에 대한 고찰

이정동,유진혁,임채윤,박성배 한국생산성학회 2001 生産性論集 Vol.15 No.2

Learning effect has implication for the performance analysis for the LCD industry which is highly process oriented and capital intensive industry. In this study, we estimate the learning parameter in that industry and investigate the difference in learning across generations. Based on the estimated learning effect, we provide some implication for the question whether the leadership in the industry is sustainable or not.

CT 유도하의 경피적 폐생검 : 임상적 의의 및 합병증에 관한 연구 A Study of Clinical Significance and Complication

박재성,백상현,차장규,홍현숙,김대호,박성진,조준희,임한혁,이혜경 순천향의학연구소 2003 Journal of Soonchunhyang Medical Science Vol.9 No.2

Purpose : To determine the diagnostic accuracy and predicting factor of pneumothorax on CT-guided percutaneous transthoracic needle biopsy. Materials and Methods : Using automated biopsy devices, 107 CT-guided percutaneous needle biopsies of pulmonary lesions were performed. Final diagnosis was made with operation or other methods. We retrospectively analyzed the frequency of complications and diagnostic yields of 107 biopsies. The clinical features, treatment, and courses of complications were reviewed, and risk factors of pneumothorax such as depth and size of lesion, CT emphysema score of whole lung and pathway of needle, and the result of pulmonary function test were analyzed. Result : 96 biopsies(89.7%) yielded sufficient tissue for pathologic evaluation. For cases of malignant and benign disease, sensitivity was 91.5% and 87.5% respectively; the corresponding figures for diagnostic accuracy were 88.1% and 77.1%. So, sensitivity and diagnostic accuracy of percutaneous transthoracic needle biopsy was 89.7% and 83.2%. Eighteen(16.8%) of 107 patients developed pneumothorax and 3 of these required application of chest tube or percutaneous catheter drainage. In the group with pneumonthorax, the lesion was significantly smaller(p=0.029) and higher CT emphysema score of pathway of needle(p=0.032). But there were no significant difference between two groups(with or without pneumothorax) for depth of lesion, pulmonary function test(% predictive value of FEV1 and FEV1/FVC) and CT emphysema score of whole lung. Conclusion : CT-guided transthoracic needle biopsy of the pulmonary lesions is safe and easy method of obtaining specimens of good quality and quantity. It may be an useful procedure in the diagnosis of localized pulmonary lesions. For the prediction of pneumothorax, size of lesion and CT emphysema score of pathway of a needle are significant risk factors.

CdSe-sensitized Photoelectrochemical Solar Cell Prepared by Spray Pyrolysis Deposition Method

Im, Sang-Hyuk,Lee, Yong-Hui,Seok, Sang-Il The Korean Electrochemical Society 2011 한국전기화학회지 Vol.14 No.2

We fabricated CdSe-sensitized photoelectrochemical solar cell by depositing CdSe nanoparticles on nanoporous $TiO_2$ (np-$TiO_2$) via spray pyrolysis deposition method. By adjusting the amount of CdSe-sensitizer deposited on np-$TiO_2$, we can fabricate an efficient CdSe-sensitized solar cell (${\eta}$ = 3.0% under 1 sun irradiation) in polysulfide liquid electrolyte.

Long-Term Incidence and Predicting Factors of Cranioplasty Infection after Decompressive Craniectomy

Im, Sang-Hyuk,Jang, Dong-Kyu,Han, Young-Min,Kim, Jong-Tae,Chung, Dong Sup,Park, Young Sup The Korean Neurosurgical Society 2012 Journal of Korean neurosurgical society Vol.52 No.4

Objective : The predictors of cranioplasty infection after decompressive craniectomy have not yet been fully characterized. The objective of the current study was to compare the long-term incidences of surgical site infection according to the graft material and cranioplasty timing after craniectomy, and to determine the associated factors of cranioplasty infection. Methods : A retrospective cohort study was conducted to assess graft infection in patients who underwent cranioplasty after decompressive craniectomy between 2001 and 2011 at a single-center. From a total of 197 eligible patients, 131 patients undergoing 134 cranioplasties were assessed for event-free survival according to graft material and cranioplasty timing after craniectomy. Kaplan-Meier survival analysis and Cox regression methods were employed, with cranioplasty infection identified as the primary outcome. Secondary outcomes were also evaluated, including autogenous bone resorption, epidural hematoma, subdural hematoma and brain contusion. Results : The median follow-up duration was 454 days (range 10 to 3900 days), during which 14 (10.7%) patients suffered cranioplasty infection. There was no significant difference between the two groups for event-free survival rate for cranioplasty infection with either a cryopreserved or artificial bone graft (p=0.074). Intergroup differences according to cranioplasty time after craniectomy were also not observed (p=0.083). Poor neurologic outcome at cranioplasty significantly affected the development of cranioplasty infection (hazard ratio 5.203, 95% CI 1.075 to 25.193, p=0.04). Conclusion : Neurologic status may influence cranioplasty infection after decompressive craniectomy. A further prospective study about predictors of cranioplasty infection including graft material and cranioplasty timing is necessary.

Multiple-Layered Colloidal Assemblies via Dipping Method with an External Electric Field

Sang Hyuk Im,O Ok Park,Moo Hyun Kwon 한국고분자학회 2003 Macromolecular Research Vol.11 No.2

Reorientation of Colloidal Crystalline Domains by a Thinning Meniscus

Sang Hyuk Im,O Ok Park,Moo Hyun Kwon 한국고분자학회 2004 Macromolecular Research Vol.12 No.2

Fabrication of Polymeric Hollow Spheres Having Macropores by a Quenching and Sublimation Process

Im, Sang-Hyuk,Park, O-Ok,Kwon, Moo-Hyun The Polymer Society of Korea 2003 Macromolecular Research Vol.11 No.6

We fabricated polymeric hollow spheres having macropores, which combine the advantageous properties of porous materials and hollow spheres. To fabricate such spheres, a polystyrene/methylmethacrylate solution was dispersed in water by vigorously stirring and then the suspension was quenched using liquid nitrogen. Water and methyl methacrylate present in the quenched suspension were readily sublimated by freeze-drying. Conclusively, the hollow-sphere structure and the macropores of its shell were created by the processes of liquid nitrogen-quenching and sublimation of methyl methacrylate domains within the shell, respectively.