국내 중소건설 현장의 중대재해 발생행태에 대한 대책안

손병남,최응규,조용훈 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(계획계)

This study examines the severe disasters' examples occurred frequently at construction site, which can be classified as laborers' failing, and structures' collapse, etc. Based on the examples and former studies, some guidelines to prevent these kinds of disasters are suggested.

지역의무 공동도급 수주에 의한 공사현장 운영실태 연구

임의수,최응규,조용훈 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1

Since the systematic researches on the operation for compulsory local joint contract are not enough, it is required to make efforts the sound activation of this system. This study analyzes and examines the problems occurred at the operation of construction field due to compulsory local joint contract. And tries to suggest effective operational guidelines

Breeding of High Quality Hydrid Cultivars of Korean Melon (Cucumis melo L.) with Tender Rind

Eung Kyoo Choi,Un Soon Hwang,Byung-Soo Kim,Hong Jib Choi,Jong-Do Chung,Su Hwan Oh 한국원예학회 2019 한국원예학회 학술발표요지 Vol.2019 No.5

보강섬유와 시멘트와의 매트릭스(Matrix) 구조에서 계면가교제가 계면결착에 미치는 특성

최응규(Choi Eung-kyoo) 대한건축학회 2003 大韓建築學會論文集 : 構造系 Vol.19 No.7

It is necessary to reinforce the interfacial adhesion between components in fiber reinforced cement composite either by surface treatment thereby producing interfacial attraction or by reinforce the interfacial adhesion between organic and inorganic materials by means of coupling agent. The objective of the study is to propose a practical approach in selecting a suitable interfacial coupling agent for an assorted reinforcing fiber and cement compounds and to determine the most appropriate coupling agent for a particular combination. The experiment analyzed the integrity of the interfacial adhesion by means of VMS(video microscope system) as well as by measurement of interfacial adhesion, demonstrating polyacrylamide, a polymeric coupling agent, being the most effective coupling agent for the purpose of reinforcing the interfacial adhesion between reinforcing fiber and cement. There are three different kinds of PAM depending on the ionization; N-PAM, A-PAM and C-PAM, each reinforcing fiber material having its own optimum PAM. The experiment has demonstrated that N-PAM was least effective for all the reinforcing fibers used in the analysis. While A-PAM coupling agent was most effective in PVA fibers, C-PAM proved to be the most effective coupling agent in both acrylic and carbon fibers.

섬유강화 시멘트복합체에서 목재해면펄프가 섬유분산고착 및 계면구조에 미치는 영향

최응규(Choi Eung-Kyoo),이재용(Lee Jae-Yong),이찬식(Lee Chan-Sik) 대한건축학회 2004 大韓建築學會論文集 : 構造系 Vol.20 No.5

The aim of the study is to analyze characterized dispersion and arrangement of reinforcing fibers within cement composites<br/> among various reinforcing fiber materials, and to analyze physical and mechanical properties of cement composite specimens when<br/> the content of wood pulp is brought up to 4.0%. Based on the result of the experiment, the study is also to examine the effects<br/> of wood pulp on interfacial matrix and physical properties of cement composite and to determine optimal wood pulp material to be<br/> used for cement composite.<br/> Having analyzed the effects of wood pulp upon interfacial matrix and physical properties of cement composite, softwood pulp<br/> has demonstrated excellent interfacial adhesion and mechanical properties due to presence of abundant fibroids and fibrillation.<br/> While recycled sulfite wood pulp has exhibited relatively poor mechanical properties as compared to softwood pulp because of low<br/> tensile strength of the pulp fibers, hardwood pulp has demonstrated the poorest mechanical properties due to low content of fibers<br/> and brittleness. The study has demonstrated softwood pulp to be the most suitable material in terms of physical properties of<br/> cement composite for the purpose of reinforcing and dispersion of fibers.<br/> Because of the excellent hydrophilic and coagulating characteristics in water, wood pulp is proved to be an effective agent for<br/> uniform dispersion and maintaining the consistency of reinforcing fibers regardless of its kind. Whereas softwood pulp proved to<br/> be the most superior material, recycled sulfite wood pulp may be preferred in terms of economy with reasonable physical<br/> properties.

목재펄프의 특성 및 함량이 무기섬유보강 시멘트복합체의 내부구조 및 물성에 미치는 영향연구

최응규(Choi Eung-Kyoo),김옥규(Kim Ok-Kyue),양극영(Yang Keek-Young) 대한건축학회 2004 大韓建築學會論文集 : 構造系 Vol.20 No.4

The objective of the study is to suggest a suitable woodpulp material and its optimum content applicableto carbon<br/> fiber-reinforced cement composite. Following selection of a suitable carbon fiber within a range of inorganic fiber materials, a<br/> series of experiments has been carried out to analyze the effects of varying woodpulp contents and its characteristics in cement<br/> composite with respect to physical and mechanical properties.<br/> The experiments have demonstrated that fibrin and fibril in the woodpulp play important roles in the inorganic fiber-reinforced<br/> cement composite using carbon fiber; moderates inherent brittleness: disperses fibers uniformly: maintains the consistency of the<br/> mixture. Analyzing the properties of carbon fiber-reinforced cement composite in relation to the varying contents of woodpulp, the<br/> fibrin content in the woodpulp had significant effect upon the physical properties. In addition, the degree of fibrilization of<br/> woodpulp determines the mechanical properties. In brief, softwood pulp having tougher fibers and broader fibrin with rich<br/> fibrilization demonstrated better mechanical performance in the cement matrix. Observing the interfacial failure plane, while<br/> excessive content of woodpulp in the cement matrix exhibited loose matrix structure with voids, 2.5% woodpulp content proved to<br/> be optimum showing compact matrix structure.<br/> Based on the result of the experiment, softwood pulp with rich fibrin content and well-developed fibrilization proved to be the<br/> optimum woodpulp for inorganic fiber-reinforced cement composite. Optimum physical properties were obtained at the ranges of<br/> 2.5% to 3.0% in the woodpulp content. When carbon fiber is used as reinforcingfiber, the most effective content of woodpulp in<br/> the mix to moderate brittleness of carbon fiber turned out to be approximately 3.0%.

Pyrazinamide의 신배설기전에 관한 약동학적 연구

최응상(Eung-Sang Choi),신상구(Sang-Goo Shin),이선희(Sun-Hee Lee),최철희(Cheol-Hee Choi),김용식(Yong-Sik Kim),임정규(Jung-Kyoo Lim),박찬웅(Chan-Woong Park) 대한약리학회 1987 대한약리학잡지 Vol.23 No.1

가토에서 체중 kg당 40mg 용량을 15분간 단기 주입 또는 일정 혈중농도 유지를 위한 지속 주입 방법으로 pyrazinamide를 투여 후 혈청농도 및 뇨중 배설량을 축정하여 이의 신장 배설 기전을 약동학적으로 분석하고 분포기 이후의 조직농도 측정으로 다음과 같은 결과를 얻었다. 1. 가토에서 pyrazinamide의 약동학적 분석을 compartmental model에 적용시 분포기의 반감기는 2.38 ± 0.57시간이었으며 V_c(central compartment의 용적)는 체중 kg당 349.96 ± 70.99㎖이었고 총 분포 용적 (V_dss)은 907.00 ± 255.61㎖이었다. 2. Non-compartmental model parameter는 총 분포 용적(V_dss)은 체중kg당 953.34 ± 362.02㎖이었으며 평균 체내 잔류 시간(MRT_iv)은 3.30 ± 0.84시간이었고 신 청소율은 112.26ml/kg 로 총 청소율의 39.5%에 해당하였다. 3. pyrazinamide의 혈청 단백 결합율은 5 ~ 100μg/㎖의 범위에서 12.50-1.80%의 결합율을 보였다. 4. pyrazinamide의 분포기 이후 조직/혈청 농도비는 약물 투여 방법에 따라 지속 정맥주입에 따른 steady-state 유지시 15분 정주 방법시 보다 낮은 값을 보였으며 steady-state 상태의 조직 분포율은 신장에서 가장 높았고(1.68 ± 0.53), 근육에서 가장 낮은 값(1.10 ± 0.46)을 보였다. 5. 가토에서의 pyrazinamide의 신장 청소율은 혈청 농도 변화에 비직선적인(non-linear) 관계를 보였다. 6. pyrazinamide의 신장 현성 운반량(apparent transport)은 혈청 Pyrazinamide농도 10μg/㎖까지는 양성 균형을 보였으나 이후 혈청 농도의 증가에 따라 현저한 음성균형을 보였다. 7. pyrazinamide의 신장을 통한 분비율(excretion ratio, ER)은 혈청농도 증가에 따라 현저히 감소하는 양상을 보이며 60μg/㎖의 농도에서 약 0.3의 ER치를 보여 70% 이상의 재흡수율을 나타냈다. 8. 혈청 pyrazinamide농도를 일정히 유지하고 뇨량 변화시 pyrazinamide의 신장 청소율은 뇨량 증가에 의존적인 상승을 보였다. 이상의 실험 결과로 pyrazinamide의 신장 배설은 사구체 여과와 더불어 세뇨관 분비 기전이 존재하고 비교적 빠른 확산속도를 보이는 세뇨관 재흡수 기전에 의해 신장 배설이 조절됨을 추정할 수 있었다. The renal handling and tissue distribution of pyrazinamide were studied after administration of single dose intravenous injection for 15 min or constant infusion in New Zealand White rabbits. Peak pyrazinamide serum concentration ranged from 57.3 to 105.0μg/ml (mean ± SD;83.0 ± 17.8). The mean half-life of the a phase was 0.143 ± 0.047 hr while the β phase ranged from 1.66 to 3.25 hr(mean ± SD;2.38 ± 0.57). The mean steady-state volume of distribution in non-compartmental model was 0.935 ± 0.362 L/kg Excretion ratio of pyrazinamide was dramatically reduced from 1.02 to 0.30 when unbound serum pyrazinamide concentration was increased from 6.04 to 60.9μg/ml. The urine flow dependency of renal clearance of pyrazinamide was demonstrated in steady-state serum concentration. The tissue/serum concentration ratio of pyrazinamide was highest in kidney and lowest in skeletal muscle among the tissues examined. The results suggested that a large fraction of pyrazinamide filtered by glomerulus and secreted by renal tubule was reabsorbed and this tubular reabsorption of pyrazinamide might be greatly influenced by urine flow.

무기충전재 함량에 따른 PVA섬유강화 시멘트복합체의 계면결착특성 및 물성고찰

최응규(Choi Eung-Kyoo) 대한건축학회 2003 大韓建築學會論文集 : 構造系 Vol.19 No.8

The aim of the study is to suggest an optimal inorganic filler and its contents applicable to PVA fiber reinforced cement matrix by means of quantifying the degree of interfacial adhesion between a selected range of inorganic filler materials and PVA fibers followed by analyzing physical and mechanical properties of PVA fiber reinforced cement composite in relation to the contents of inorganic filler. Based on the result of analysis on interfacial adhesion between inorganic filler and PVA fiber materials, kaolin, fly ash andmica have proved to be excellent filler materials for cement matriceshaving superior adhesion performance with PVA fibers.Compactness of cement matrix is influenced by chemical components and their content of the respective filler material being used.In addition physical properties are heavily affected by type of filler materials and its configuration. Observing the failure plane ofPVA fiber-reinforced cement composite mixed with one of the optimal filler materials, mica, the specimens have exhibited highdegree of compactness with little PVA fibers pulled out within the cement matrix. The key elements in producing fiber reinforced cement matrix using a range of filler materials are: (1) Selection of filler material chemically compatible with reinforcing fibers (2) Maintaining maximum adhesion between reinforcing fiber and filler material (3) Use of optimal content of filler materials. The experimental study has determined that when PVA fiber is used in cement matrix, mica proved to be the most suitable filler material and the range of content is from 20% to 25%.

무기섬유보강 시멘트복합체에서 계면결착제가 무기섬유계면에 미치는 영향

최응규(Choi Eung-kyoo),고성석(Go Seong-seok),김선국(Kim sun-kuk) 대한건축학회 2003 大韓建築學會論文集 : 構造系 Vol.19 No.4

The objective of the study is to examine the characteristic correlations between reinforcing inorganic fiber and interfacial adhesion agent since the interfacial adhesion strength between reinforcing inorganic fiber and matrices is believed to be an essential element influencing the physical properties in inorganic fiber reinforced cement composite using slurry method. The integrity of interfacial adhesion between reinforcing fiber and cement not only affects the quality of fiber reinforced cement composite but also influences to a large degree the physical properties of the cement composite when producing inorganic fiber reinforced cement composite using slurry method. IIaving analyzed the physical properties i.e., water content, tensile strength, flexural strength and flexural toughness of inorganic fiber reinforced cement composite specimens, C-PAM(cation polyacrylamide) was determined to be an optimum interfacial adhesion agent. The study has also demonstrated that interfacial adhesion strength varies large]y on the content and type of the reinforcing fiber. Judging from magnified view of the tensile shear cross-section using VMS (video microscope system), interfacial adhesion strength between reinforcing fiber and matrices is affected by the type of interfacial adhesion agent. According to the result of the experiments, C-PAM was determined to be an ideal interfacial adhesion agent when using carbon fiber in producing inorganic fiber reinforced cement composite with the optimum content of carbon fiber being estabJished.

무기질섬유 계면처리에 따른 무기섬유강화 시멘트복합체의 계면결착특성에 관한 연구

최응규(Choi Eung-Kyoo),김연희(Kim Yeon-Hee) 대한건축학회 2009 大韓建築學會論文集 : 構造系 Vol.25 No.3

The purpose of this study was to present surface adhesion characteristics of inorganic fiber-reinforced cement composite based on the results of experiment on the cement composite by the interfacial agent for the inorganic fiber PAM (Polyacrylamide). To improve surface adhesion between the inorganic fiber and cement in the inorganic fiber-reinforced cement composite, N-PAM (Nonion), C-PAM (Cation) and A-PAM (Anion), etc. were used as interfacial adhesives. Analysis of the physical properties of inorganic fiber-reinforced cement composite showed that C-PAM adhesive is an optimal interfacial treatment agent for the carbon fiber, whereas A-PAM adhesive is optimal for the epoxy coating carbon fiber. The excellent interfacial adhesion and physical properties of the cement composite were likewise revealed. Besides, the study of the tensily crushed cross section of the cement composite showed that the cement composite using interfacial treatment of the inorganic fiber manifests excellent refinement in the inner structure and interfacial adhesion, along with improved relevant physical properties. Results showed that the epoxy coating carbon fiber has better interfacial adhesion than the carbon fiber. When interfacial adhesion is reinforced by the interfacial adhesive for inorganic fiber, C-PAM was found to be suitable for the carbon fiber, whereas A-PAM adhesive was suitable for the epoxy coating carbon fiber. Analysis of the physical properties of inorganic fiber-reinforced cement composite showed that the epoxy coating carbon fiber has stronger interfacial adhesion to the cement interfacial structure, and better physical characteristics and mechanical properties than the carbon fiber.