• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.3
• /
• pp.1684-1691
• /
• 2015

For performance improvement and compactness, usage of enhanced tube is inevitable. However, studies on enhanced tubes for generator is very limited. In this study, pool boiling tests were conducted for 7 heat transfer tubes. Test range covered pressure 7.38~101.3 kPa and heat flux $20{\sim}40kW/m^2$. Results show that boiling heat transfer coefficient increases as pressure or heat flux increases. Under atmospheric condition, high heat transfer coefficients were obtained for notched fin and low fin tubes(225% and 202% of the 19.0 mm smooth tube, which yielded the lowest heat transfer coefficient). As pressure decreased, high heat transfer coefficients were obtained for a low fin tube(290% and 288% of the 19.0 mm smooth tube at 12.34 and 7.38 kPa).

• 프린팅코리아
• /
• v.7 no.8
• /
• pp.104-105
• /
• 2008

홍익대학교 고승관 교수가 지난 7월 3일 충북도립미술관 건립을 위해 자신이 만든 작품과 함께 수집품 등을 기증했다. 특히 이번 기증은 고승관 교수가 20년간 작업해 온 286개의 돌탑과 작품 300여점 및 그동안 수집해 온 민속품 및 공예품 200점도 함께 기증했다. 이와 아울러 도립미술관 부지와 함께 미술관 건물도 함께 기증했다. 다음은 고승관 교수의 글이다.

• Journal of Korea Water Resources Association
• /
• v.38 no.7 s.156
• /
• pp.585-593
• /
• 2005

Recent concerns regarding protecting, identifying, isolating, redundant routing and dewatering of subsystems of water distribution networks have led to the realization of the importance of valves in these systems. Valves serve two purposes namely, flow and pressure control and isolating subsystems due to breakage or contaminant containment. In this paper, valves are considered from the point of view of subsystem isolation. When a water main is required to be closed, it may be in general necessary to close several other pipes in addition to the broken pipe itself depending on the distribution of adjacent valves. This set of pipes is defined as a segment. In this paper a segment analysis for isolating pipes is present and based on the segment analysis, we suggested the Valve Importance Index and the 7 performance indicators to evaluate the system performance. The suggested methodology is applied to a real network to verify the applicability of the methodology.

• The Science & Technology
• /
• v.35 no.6 s.397
• /
• pp.28-29
• /
• 2002

작년 7월에 문을 연 일본과학미래관은 21세기 첨단 과학기술의 발전과 미래사회에서의 과학기술을 체험할 수 있는 최신 과학관이다. 7층 높이의 현대식 건물에 4개층으로 이루어진 전시관 1층에는 '지구환경과 미개척의 세계'등을 비롯하여 특별전시실이 있으며 에스컬레이트를 이용하여 3층에 올라가면 '기술혁신과 미래', '정보과학과 기술'의 전시물들을 만나게 된다.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.47 no.2
• /
• pp.205-212
• /
• 2020

The purpose of this study is to evaluate the validity of primary anterior zirconia crown made with Computer Aided Design/Computer Aided Manufacturing (CAD/CAM) technology by analyzing fracture strength and translucency parameter. Zirconia crown was designed with CAD software, using 3D scanned data of #61 tooth model. Crown fabrication was performed with CAM machine using zirconia block. Zirconia crowns were divided into 3 groups according to thickness(0.3, 0.5, and 0.7 mm), and fracture strength was compared with 1.0 mm thickness of resin strip crown. The compressive force was applied with universal testing machine at 30° along the incisal edge at increments of 1 mm/min. For translucency evaluation, 0.3, 0.5, and 0.7 mm thickness of zirconia specimens were fabricated and translucency was measured with spectrophotometer. Among zirconia groups, there was a significant increase in fracture strength as thickness increased (p < 0.05). The fracture strength of zirconia crown was significantly higher than resin strip crown in all groups (p < 0.05). Translucency parameter was highest in 0.3 mm group, and significantly decreased as thickness increased to 0.5 and 0.7 mm (p < 0.05). Thin primary anterior zirconia crown can be designed and fabricated according to individual needs by using CAD/CAM. Restoration with thin crown would reduce the amount of tooth reduction, risk of pulp exposure, and make more esthetic restoration possible.

• Journal of the Korean School Mathematics Society
• /
• v.13 no.3
• /
• pp.415-442
• /
• 2010

If the philosophy of the curriculum is changed when the curriculum is revised, discussion about knowledge viewpoints in the changed philosophy is needed. The purpose of this thesis is to analyze elementary mathematics textbooks(EMT) based on the perspective of constructivism knowledge as basic philosophy of the 7th curriculum and the 2007 revised curriculum and to present aim of textbooks development through the results. According to the results, the number and operation units of 1st and 2nd grades of EMT compiled according to the 7th curriculum and the 2007 revised curriculum didn't reflect the perspective of constructivism knowledge as the philosophy of the curriculum. From the analysis, EMT were not composed so as to agree the perspective of constructivism knowledge that emphasize concepts, conceptua1 principles, variety, integration.

• 월간 기계설비
• /
• s.240
• /
• pp.48-49
• /
• 2010

지식경제부 기술표준원이 수도관, 오 배수관, 토목용 하수관으로 광범위하게 사용되는 PVC(폴리염화비닐)관의 품질과 위생기준을 강화해 지난 해 7월 1일부터 납 안정제와 가소제 등의 사용을 금지하고, 위생성 및 장기내구성 등의 품질기준이 강화된 흰색 PVC관을 상 하수도관으로 사용토록 했으나 아직도 이를 제조하거나 시공하고 있어 주의를 촉구하고 나섰다. 이에 따라 PVC관을 수도관, 오 배수관으로 시공하고 있는 설비건설업계의 주의가 요망된다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2000.04a
• /
• pp.24-24
• /
• 2000

작업 중 공구를 관에 떨어뜨리거나 작업하기 위해 관을 이동하던 중 다른 물체에 부딪힐 경우 복합재로 만들어진 관이 손상을 입게 되는 경우가 생기는데 관이 상황에 따라 얼마나 손상을 입었는지가 본 연구의 관심이다. 충격자는 직경이 25.4mm와 12.7mm인 반구형 2종류와 모서리의 직경이 15mm인 원추형 1종류로 각각 무게가 다르며, 떨어뜨리는 자유낙하 높이는 120mm에서 700mm로 종류에 따라 간격을 달리했다. 실험 장치로는 Dynatup 8250을 사용했으며 충격에너지, 최대충격하중, 충격변위, contact diameter를 측정했다. 시험 후 시편은 방사선 촬영을 하여 충격자의 종류에 따라 손상의 정도가 어떻게 다른지를 파악했다. 직경이 25.4mm인 반구형의 충격자는 표면의 손상은 적었으나 복합재 관의 내부에 delamination이 많이 생겼으며 직경이 12.7mm인 반구형의 충격자는 표면의 손상이 심했으나 내부의 delamination이 상대적으로 적었다. Contact diameter와 최대충격하중과의 관계는 실험치와 이론치가 잘 일치했으나 Kinetic energy와 최대충격하중과의 관계는 실험치와 이론치의 차이가 있었다.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.4 no.2
• /
• pp.148-154
• /
• 2001

Purpose: Ingested foreign bodies present a common clinical problem. It is well known that most of them pass uninterrupted through the gastrointestinal tract. We evaluated the role of endoscopy and Foley catheter for removal of foreign bodies in the gastrointestinal tract. Methods: We investigated retrospectively 60 cases with foreign bodies in the gastrointestinal tract. They had been treated at Wonju Christian Hospital, Yonsei University of Korea, from January, 1996 through December, 1999. Results: The age of the patients ranged from 7 months to 13 years. Patients under 5 years were 57 cases (97%) and there was no significant difference in sex (M : F=1.07 : 1). 45 cases of the patients had no symptom. The most common foreign bodies were coins (43 cases). The most common location was esophagus (31 cases). The number of foreign body removal using flexible endoscopy and Foley catheter was 22 (36.7%) and 18 (30.0%) cases, respectively. In 18 cases (30.0%), foreign bodies passed spontaneously. Only 1 case (1.7%), curtain pin impaction at ileocecal region, required surgery. Conclusion: Early foreign body removal from esophagus and stomach is recommended to lessen the morbidity and complication. Fluoroscopic foley catheter technique and flexible endoscopy for removal of esophageal foreign bodies in children is safe and effective.

• 베이커리
• /
• no.7 s.384
• /
• pp.68-69
• /
• 2000

지난 6월8일부터 12일까지 부산시 해운대구에 위치한 부산무역전시관에서 제7회 부산국제식품산업박람회가 개최됐다. 이번 행사는 6개국 88개 업체가 참가해 식품관, 식품기게관,포장기계관, 외식업프랜차이즈과 등의 4개 테마로 구성해 관람의 편의를 더했다. 부산국제식품산업박람회의 참가 업체 및 박람회의 이모저모를 살펴보았다.