• Journal of Korea Foundry Society
• /
• v.9 no.1
• /
• pp.80-88
• /
• 1989

SGCI(Spheroidal Graphite Cast Iron), CVGCI(CV Graphite Cast Iron) and FGCI(Flake Graphite Cast Iron) having different contents of Mn($0.25%{\sim}0.85%$) and Ni($0.3%{\sim}1.2%$) were produced, respectively. The thermal expansion and thermal conductivity of the cast iron were investigated in the temperature range of $50^{\circ}C{\sim}300^{\circ}C$. As the graphite nodularity of the cast iron increases, thermal expansion coefficient increases, thermal conductivity and electrical conductivity to thermal conductivity ratio decrease. The thermal expansion coefficient of the cast iron increases with increasing Mn content and decreases with increasing Ni content. The thermal conductivity of the cast iron decreases with increasing Mn and Ni contents.

• Journal of Chest Surgery
• /
• v.28 no.4
• /
• pp.376-380
• /
• 1995

We experienced 17 skeletal muscle transpositions in chest surgery during the past 8 years. There were 3 female and 14 male patients with ranging from 5 to 71 years of age [ average 47.3 Seventeen patients underwent 27 musele flaps : 11 latissimus dorsi, 6 pectoralis major, 6 serratus anterior and 4 other muscles. An average of 2.0 previous operations was performed. Hospitalization averaged 24 days.Follow up ranged from 7 days to 45 months;There were two postoperative deaths; one, 20 days after from operation due to pneumonia and the other, 130 days after from operation due to cor pulmonale.Fifteen patients who were alive after operation had good results at the time of last follow up.

• Journal of the Microelectronics and Packaging Society
• /
• v.5 no.2
• /
• pp.13-20
• /
• 1998

고속 디지털 MCM 응용을 위해 MCM-D 와 MCM-SLC 배선에서 CMOS 버퍼의 신호상승시간에 따른 신호전송특성을 연구하였다. 고속신호처럼 버퍼의 내부저항이 배선의 임피던스보다 작아 발생하게 되는 과도한 ringing은 MCM-D와 같이 lossy line의 전송감쇠 효과로 overshooting 이나 undershooting을 줄일 수 있지만 ringing에 의한 신호왜곡을 근 본적으로 막기위해서는 CMOS버퍼와 배선사이에 적절한 종단을 통해 임피던스 비해 크면 배선의 캐패시턴스에 의해 RC 지연이 증가한다. 그런데 MCM-D 배선은 단위길이당 캐패 시턴스도 작고 배선길이를 줄일수 있으므로 총 RC 지연은 MCM-SLC보다 작았다. 결론적 으로 MCM-D 배선이 MCM-SLC 배선에 비해 고속 디지털 MCM기판으로 적합한 것을 알 수 있었다.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.16 no.3
• /
• pp.43-50
• /
• 2012

The FEMA P695 document proposed a methodology to evaluate the collapse safety of a structure and the validity of the seismic design coefficients. In this study, the seismic performance of six- and twelve-story staggered wall structures with a middle corridor was evaluated based on the FEMA P695 procedure. The analysis results of the prototype structures were compared with those of the structures with an increased coupling beam depth or an increased re-bar ratio of the coupling beams in order to investigate the effect of retrofit. The adjusted collapse margin ratios (ACMR) of the model structures obtained from incremental dynamic analyses turned out to be larger than the specified limit states of an ACMR of 20%, which implies that the analysis model structures have enough strength against design level earthquakes. It was also observed that the increase in the re-bar ratio of the coupling beams between the staggered walls was more effective in increasing the ACMR than an increase in the depth of the coupling beams.

• Journal of Korean Society of Steel Construction
• /
• v.27 no.6
• /
• pp.525-536
• /
• 2015

An experimental study was performed to investigate the axial-flexural load-carrying capacity of concrete-encased and-filled steel tube (CEFT) columns. To restrain local buckling of longitudinal bars and to prevent premature failure of the thin concrete encasement, the use of U-cross ties was proposed. Five eccentrically loaded columns were tested by monotonic compression. The test parameters were axial-load eccentricity, spacing of ties, and the use of concrete encasement. Although early cracking occurred in the thin concrete encasement, the maximum axial loads of the CEFT specimens generally agreed with the strengths predicted considering the full contribution of the concrete encasement. Further, due to the effect of the circular steel tube, the CEFT columns exhibited significant ductility. The applicability of current design codes to the CEFT columns was evaluated in terms of axial-flexural strength and flexural stiffness.

• Journal of the Korea Concrete Institute
• /
• v.15 no.5
• /
• pp.697-704
• /
• 2003

The purpose of this experimental study is to investigate the relationship of the shear behavior and the variety of width, depth and location of an opening in reinforced concrete deep beams with rectangular web openings, and to present an improved shear strength equation of those members. The main parameters considered were concrete strength(fck), shear span-to-overall depth ratio(a/h), and the size and vortical position of the web openings. Twenty five deep beams were tested under two symmetric loading-points. Test results showed that the shear behavior of deep beams with web openings was influenced by a/h and the size of opening. In addition, the KCI shear design provision is a tendency to be more unconservative according to the increase in a/h and the area-ratio of opening to shear span(Ao/Ash). Based on the concrete strut action of top and bottom member of an opening and the tie action of longitudinal reinforcement, a proper design equation which closely predicts the capacity of deep beams with rectangular openings is developed.

• Journal of Korean Society of Steel Construction
• /
• v.25 no.6
• /
• pp.635-647
• /
• 2013

PSRC composite column is a concrete encased steel angle column. In the PSRC composite column, the steel angles placed at the corner of the cross-section resists bending moment and compression load. In the present study, using the performance criteria in KBC 2009, cyclic lateral loading test was performed for PSRC columns to verify the seismic performance. The test parameters were the column type, the use of continuous hoop, and the use of studs for steel angle. 2/3 scale specimens of a conventional composite column and three PSRC columns were tested. The test results showed that the load-carrying capacity predicted by KBC 2009 correlated well with the test results. The specimens also exhibited good deformation and energy dissipation capacities. After concrete cover spalling under cyclic loading, the load-carrying capacity were decreased by buckling of longitudinal bars and steel angles. When continuous hoop was used, the deformability of the PSRC column was improved, preventing early buckling of the steel angles.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.9 no.3 s.43
• /
• pp.77-85
• /
• 2005

After the collapse of the World Trade Center in september 11, 2001 and due to the frequent fire-caused damages of buildings during earthquake attacks, social concerns have been increased for the fire proof of the structural members of buildings. Recently, researches have been conducted to improve the fire resistance for building members not by the traditional ways but by utilizing the fire-resisting characteristics of reinforced concrete and structural characteristics of H-steel. In this paper, laboratory tests were conducted in room temperature to investigate the structural performance of the composite beams, which were developed to improve the fire resistance, comprising with concrete incasement between upper and lower flanges of H steel. From the experimental results, the displacement ductility factors of $6\~8$ were obtained. The difference of flexural behavior ol H steel-partial concrete incased composite beams with various composite details seems to be minor. The amount of longitudinal rebars is the most influential factor for the flexural strength of the composite beams. Therefore, if this type of composite beams are selected for designing a building located in moderate seismic lone, identical beam size could be used in several stories of the building.

• Journal of the Korea Concrete Institute
• /
• v.28 no.1
• /
• pp.13-21
• /
• 2016

A hybrid precast concrete beam system with a simple rigid connection was proposed to compensate the limitations and shortcomings of the conventional bolt connection associated with the H-beams embedded into concrete beams. Three beam specimens with fixed both ends were tested under one-point top cyclic loading to explore the effectiveness of the developed hybrid beam system in transferring externally applied flexure to a column. The main parameter considered was the length ($L_s$) of H-beam, which was selected to be $0.25L_I$, $0.5L_I$, and $1.0L_I$, where $L_I$ is the distance from the support to the point of inflection. All beam specimens showed a better displacement ductility ratio than the reinforced concrete beams with the same longitudinal reinforcement index, indicating that the cyclic load-deflection curve and ductility were insignificantly affected by $L_s$. The continuous strain distribution along the beam length and the prediction of the ultimate load based on the collapse mechanism ascertained the structural adequacy of the developed rigid connection.

• Journal of the Korea Concrete Institute
• /
• v.20 no.3
• /
• pp.335-343
• /
• 2008

In order to improve the workability in erecting Precast Concrete (PC) members and enhance the seismic resistance capacity of the joints in PC moment frames, a new PC column and its construction process are introduced in this paper. This column is manufactured by centrifugal force in keeping the hollow tube inside; the hollow is little bit wide and the grout can be poured from top to bottom after erection at site so that more compact grouting is possible in horizontal joint. The repeated cyclic loading test for four full scaled specimens was conducted to evaluate the seismic resistance capacity of the joint designed by the proposed system. For the continuity of main reinforcements in column, two connecting methods are used in designing specimens; one is to use mechanical connector and other is lab splice. From the cyclic lateral loading test, it was found that the seismic capacity of the developed PC column joint is comparable to that of monolithic joint.