• 한국건축시공학회지
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• 제11권6호
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• pp.530-537
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• 2011

연구는 SHCC의 건축시공 현장적용을 목적으로 현장 제조설비인 배치플랜트 2-Shaft 믹서를 이용하여 SHCC 제조 및 타설을 통해 실부재 실험을 실시하고, 이를 실내실험 결과와 비교 검토함으로서 향후 SHCC의 현장적용을 위한 기초자료로 제시하고자 하였다. 그 결과, 실내 Omni 믹서와 2-Shaft 믹서에서 SHCC 제조시 인장강도는 유사하였지만, 변형률에서 Omni 믹서가 2.5 % 이상 우수하였다. 배치플랜트 3500 L 2-Shaft 믹서에서 제조된 SHCC의 경우, 실내 100 L 2-Shaft 믹서에서 제조한 SHCC에서 인장 성능이 보다 높게 나타났다. SHCC의 현장적용 확대를 위해서는 배치플랜트 현장 제조시 건비빔, 모르타르 비빔시간을 충분히하여 매트릭스를 균질성을 확보하고, 비빔단계에서 적절한 점성 및 유동성을 확보할 수 있는 다양한 방법을 고려해야 한다.

• Journal of Periodontal and Implant Science
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• 제32권1호
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• pp.13-23
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• 2002

The ultimate goal of periodontal therapy is directed to arresting the progression of the disease, and regenerating the fibrous attachment. In order to achieve such treatment aim, the plaque and calculus must be eliminated and the physiological conditions of the root surface must be changed to facilitate the attachment and migration of the new fibroblasts, The method of changing the proper root surface conditions to promote the healing of periodontal tissue involves mechanical procedures, such as scaling and root planing, and chemical procedures such as tetracycline-HCl. However, the formation of a long junctional epithelium was most frequently observed type of healing. Thus, the aim of this study was to examine in vitro the influence of surface conditioning of dentin by TC-HCl on human gingival epithelial cell attachment. Human gingival epithelial cells were obtained from healthy retromolar pad area(under the age 23 years). Seventy two teeth extracted from severe periodontitis were used as study material. To evaluate the epithelial cell attachment to dentin, the prepared specimen was divided to four groups. For the control group, only scaling and root planing were carried out, and for the test group, 1 to 3, the concentration of the TC-HCl was 50, 125 and 250mg/ml respectively. After cell cultivation time of 1-, 3-. 24 hour, for the indirect quantitative assessment of gingival epithelial cell attached to dentin sample, the absorbance of epithelial cell unattached to dentin was measured. The results were as follows; 1. There was no statistically significant difference between scaling and root planing group and TC-HCl 50mg/ml 125mg/ml and 250mg/ml group about absorbance of unattached epithelial cell to dentin sample(p>0.5). 2. As time passes, the absorbance of unattached gingival epithelial cell to dentin sample was decreased statistically significant(p<0.05). 3. There was no statistically significant difference among the TC-HCl group(p>0.05) We concluded that there was similar effect on gingival epithelial cell attachment between TC-HCl conditioning on root surface and only scaling and root planing treatment

• 수면정신생리
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• 제4권2호
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• pp.129-139
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• 1997

수면 무호흡을 포함한 다양한 원인의 수면과 관련된 호흡장애를 동반한 환자들에서는 여러가지 심혈관계 기능부전이 초래되어 이들 환자의 임상경과에 중대한 영향을 미친다. 수면 무호흡증후군, 특히 폐쇄성 수면 무호흡증후군은 수면장애의 여러 가지 원인 중 임상영역에서 가장 흔히 볼수 있는 질환으로 전신성 고혈압, 심부정맥, 폐동맥 고혈압 및 우심실 부전, 협심증 및 심근경색증, 뇌졸증등의 발병률이 정상인에 비하여 현저히 높은 것으로 알려져 있다. 폐쇄성 수면 무호흡과 달리 중추성 수면 무호흡은 수면중에 호흡중추를 불안정하게 하는 다양한 원인에 의해 발생하며 역시 심혈관계의 기능에 영향을 미칠 수 있다. 수면중에 환기장애가 더욱 악화될 수 있는 호흡기계 질환이 있는 환자들은 수면 무호흡증후군과 달리 만성적인 저산소증과 고탄산증이 동반되며 이로 인해 심부정맥, 폐동맥 고혈압, 우심실 부전(폐성심) 등의 심혈관계 이상이 초래될 수 있다. 따라서 수면 무호흡을 포함한 수면과 관련된 호홉 장애의 진단과 치료에 있어서는 호흡기계 질환에 대한 정확한 평가와 더불어 동반될 수 있는 심혈관계의 기능부전에 대한 정밀한 분석이 반드시 필요하며, 이들 자료를 바탕으로 기관절개술, 기계적 호흡, 지속적 양압공급치료, 적절한 산소요법 등의 적극적이고도 효과적인 치료법을 적용함으로서 심혈관계 합병증의 발생과 이로 인한 사망률을 감소시킬 수 있을 것으로 생각된다.

• 청정기술
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• 제20권4호
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• pp.439-448
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• 2014

포항철강산업단지의 온실가스 잠재 감축량에 대한 연구를 수행하였다. 2010년 기준 철강산단의 온실가스 배출량은 4,174,000~4,574,000 $tCO_2-eq$로 추정되고, 정부의 온실가스 감축 목표를 달성하기 위해서 2020년까지 최소 552,000 $tCO_2-eq$의 온실가스 감축이 요구된다. 온실가스 잠재 감축량을 추정하기 위하여, 자발적 온실가스 감축사업에 등록된 사례 기술들을 온실가스 목표관리제도 대상으로 지정된 51개 기업의 공정에 적용하였다. 기술적 용이성과 투자비 회수기간 측면에서 분석한 결과, 연료전환과 폐열회수를 이용하여 단기적으로 160,000 $tCO_2-eq$를 감축할 수 있는 것으로 예상된다. 중기적으로는 철강금속 산업 분야에 적용 가능한 열 부문과 전기 부문 기술을 이용하면 각각 229,000과 125,000 $tCO_2-eq$를 감축할 수 있을 것으로 예상된다. 온실가스 예상 목표 감축량 대비 중 단기 기술로 달성할 수 없는 차이(38,000 $tCO_2-eq$)에 대해서는 장기적으로 근본적인 공정 혁신과 최신 설비 및 신재생에너지 기술 도입을 통한 감축 노력이 필요하다.

• Geomechanics and Engineering
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• 제9권5호
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• pp.619-629
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• 2015

Influenced by various mining activities, fractures in rock masses have different densities, set numbers and lengths, which induce different mechanical properties and failure modes of rock masses. Therefore, precisely expressing the failure criterion of the fractured rock influenced by coal mining is significant for the support design, safety assessment and disaster prevention of underground mining engineering subjected to multiple mining activities. By adopting PFC2D particle flow simulation software, this study investigated the propagation and fractal evolution laws of the micro cracks occurring in two typical kinds of rocks under uniaxial compressive condition. Furthermore, it calculated compressive strengths of the rocks with different confining pressures and box-counting dimensions. Moreover, the quantitative relation between the box-counting dimension of the rocks and the empirical parameters m and s in Hoek-Brown strength criterion was established. Results showed that with the increase of the strain, the box-counting dimension of the rocks first increased slowly at the beginning and then exhibited an exponential increase approximately. In the case of small strains of same value, the box-counting dimensions of hard rocks were smaller than those of weak rocks, while the former increased rapidly and were larger than the latter under large strain. The results also presented that there was a negative correlation between the parameters m and s in Hoek-Brown strength criterion and the box-counting dimension of the rocks suffering from variable mining activities. In other words, as the box-counting dimensions increased, the parameters m and s decreased linearly, and their relationship could be described using first order polynomial function.

• Advances in concrete construction
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• 제10권2호
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• pp.171-183
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• 2020

The main objective of this study is the assessment of the ability of limestone mortars to resist to different chemical attacks. The ability of polypropylene (PP) fibres waste used as reinforcement of these concrete materials to enhance their durability is also studied. Crushed sand 0/2 mm which is a fine limestone residue obtained by the crushing of natural rocks in aggregates industry is used for the fabrication of the mortar. The fibres used, which are obtained from the waste of domestic plastic sweeps' fabrication, have a length of 20 mm and a diameter ranging between 0.38 and 0.51 mm. Two weight fibres contents are used, 0.5 and 1%. The durability tests carried out in this investigation included the water absorption by capillarity, the mass variation, the flexural and the compressive strengths of the mortar specimens immersed for 366 days in 5% sodium chloride, 5% magnesium sulphate and 5% sulphuric acid solutions. A mineralogical analysis by X-ray diffraction (XRD) and a visual inspection are used for a better examination of the quality of tested mortars and for better interpretation of their behaviour in different solutions. The results indicate that the reinforcement of limestone mortar by PP fibres waste is an excellent solution to improve its chemical resistance and durability. Moreover, the presence of PP fibres waste does not affect significantly the water absorption by capillarity of mortar nether its mass variation, when exposed to chloride and sulphate solutions. While in sulphuric acid, the mass loss is higher with the presence of PP fibres waste, especially after an exposure of 180 days. The results reveal that these fibres have a considerable effect of the flexural and the compressive behaviour of mortar especially in acid solution, where a reduction of strength loss is observed. The mineralogical analysis confirms the good behaviour of mortar immersed in sulphate and chloride solutions; and shows that more gypsum is formed in mortar exposed to acid environment causing its rapid degradation. The visual observation reveals that only samples exposed to acid attack during 366 days have showed a surface damage extending over a depth of approximately 300 ㎛.

• Tuberculosis and Respiratory Diseases
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• 제70권1호
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• pp.28-35
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• 2011

Background: The aim of the study was to describe the characteristics, treatments, and outcomes of critically ill patients with pandemic Influenza A/H1N1 2009 at a major medical center in Korea. Methods: This retrospective observational study examined critically ill adult patients with pandemic Influenza A/H1N1 2009, who were admitted to the AMC between August and December 2009. Results: 27 patients with confirmed pandemic Influenza A/H1N1 2009 were admitted to the intensive care unit (ICU) at the Asan Medical Center (AMC). The median age (IQR) was 59 years (41~67), and 66.7% of the patients were older than 51 years. A total of 81.5% of the patients had 2 or more co-morbidities. The median time (IQR) from symptom onset to presentation was 2 days (1~4), and the median time from presentation to ICU admission was 0 days (0~1.5). All patients received oseltamivir (300 mg/day) and 13 patients received triple combination therapy (oseltamivir, amantadine, ribavirin). Twelve patients required mechanical ventilation on the first day of ICU admission. A total of 6 patients (22.2%) died within 28 days of admission. The patients who died had significantly higher acute physiology and chronic health evaluation (APACHE) II and sequential organ failure assessment (SOFA) scores at presentation. There were no significant differences in age, co-morbidities, or antiviral regimens between survivors and non-survivors. Conclusion: Critical illness related to pandemic Influenza A/H1N1 2009 was common in elderly patients with chronic co-morbidities. All patients were given high-dose oseltamivir or triple combination antiviral therapy. Nonetheless, patients with critical illnesses associated with pandemic Influenza A/H1N1 2009 had a death rate of 22.2%.

• 폴리머
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• 제35권3호
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• pp.189-195
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• 2011

조직 형성을 위한 생리학적 환경을 제공하는 새로운 생활성 지지체의 디자인은 생체재료 연구에서 중요한 분야이다. 본 연구에서는 3차원적 실크/PLGA 지지체의 물성평가를 위해 압축강도, 수분친화도, SEM 분석을 하였으며, 세포친화성 평가를 위해 RAW 264.7과 NIH/3T3의 부착, 증식 및 표현형유지와 염증반응에 미치는 영향을 조사하였다. 지지체는 용매 캐스팅/염 추출법으로 제조하였고, 압축강도, 수분친화도 면에서 실크 함량이 20 wt%에서 우수함 확인했으며, 표면의 거침도활 높여 세포부착에 긍정적인 구조임을 확인하였다. 세포친화성 분석 결과 실크함량이 20 wt%인 실크/PLGA 지지체에서 높은 초기부작도 및 증식률을 보였으며, 실크함량이 20 wt%에서 염증반응이 눈에 띄게 감소함을 확인하였다. 조직공학적 응용에 실크/PLGA 지지체가 유용할 것이라 판단하였다.

• 대한의용생체공학회:의공학회지
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• 제27권5호
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• pp.210-217
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• 2006

Many types of interspinous distraction devices (IDDs) have been recently developed as an alternative surgical treatment to laminectomy and fusion with pedicle screws for the treatment of the lumbar spinal stenosis (LSS). They are intended to keep the lumbar spine in a slightly flexed posture to relieve pain caused by narrowing of the spinal canal and vertebral foramen. However, their biomechanical efficacies are not well known. In this study, we evaluated the kinematic behaviors and changes in intradiscal pressure (IDP) of the porcine lumbar spine implanted with IDD. For kinematics analysis, five porcine lumbar spines (L2-L6) were used and the IDD was inserted at L4-L5. Three markers (${\phi}{\le}0.8mm$) were attached on each vertebra to define a rigid body motion for stereophotogrammetric assessment of the spinal motion in 3-D. A moment of 7.5Nm in flexion-extension, lateral bending, and axial rotation were imparted with a compressive force of 700N. Then, IDD was implanted at L3-L4. IDPs were measured using pressure transducer under compression (700N) and additional extension moment (700N+7.5Nm). In kinematic behaviors, insertion of IDD resulted in statistically significant decrease 42.8% at the implanted level in extension. There were considerable changes in ROM at the adjacent levels, but statistically insignificant. In other motions, there were no significant changes in ROM as well regardless of levels. IDPs at the surgical level (L3-L4) under compression and extension moment decreased by 12.9% and 18.8% respectively after surgery (p<0.05). At the superiorly adjacent levels, IDPs increased by 19.4% and 12.9% under compression and extension, respectively (p<0.05). Corresponding changes at the inferiorly adjacent levels were 29.4% and 6.9%, but they were statistically insignificant (p>0.05). The magnitude of pressure changes due to IDD, both at the operated and adjacent levels, were far less than the previously reported values with conventional fusion techniques. Our experimental results demonstrated the IDDs can be very effective in limiting the extension motion that may cause narrowing of the spinal canal and vertebral foramens while maintaining kinematic behaviors and disc pressures at the adjacent levels.

• 한국산학기술학회논문지
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• 제20권10호
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• pp.318-325
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• 2019

최근, 스마트 농업에 대한 관심이 증가함에 따라 농업 자동화 및 로봇에 대한 연구개발이 증가하고 있다. 스마트 온실에서 사용되는 로봇은 작업 특성과 생육 환경이 고려되어야 한다. 이를 위해 스마트 온실의 환경 분석을 통해 개발되어진 방제 로봇들을 대상으로 하였다. 본 논문은 스마트 온실에 적용 가능한 방제 로봇의 요구조건을 고려한 평가방법에 대한 연구를 수행하였다. 로봇의 요구조건을 통하여 성능 및 품질 평가 기준을 수립하고 시험을 실시하였다. 로봇관련 표준을 참고하여 방제 로봇의 요구 기능과 목표를 도출하였다. 로봇의 성능을 위해 주행과 작업 능력 시험을 실시하였다. 주행시험은 로봇의 주행성능에 대한 시험을 실시하였고 작업능력은 방제성능에 대한 시험을 실시하였다. 로봇의 품질을 위해 내구성 시험을 실시하였다. 시험결과를 통하여 스마트 온실 로봇에게 요구되는 지표들을 도출할 수 있었다. 이를 통해 스마트 온실에 적용하기 위한 다양한 로봇들의 평가 기준이 될 것으로 판단된다.