• Journal of Industrial Technology
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• v.27 no.B
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• pp.83-89
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• 2007

We studied runoff characteristics of combined sewer overflows in a city while it was raining. The event mean concentration (EMC) of biochemical oxygen demand (BOD), chemical oxygen demand ($COD_{Cr}$), suspended solids (SS), total nitrogen (TN), and total phosphorus (TP) in one of the combined sewer sites in Chuncheon was 63.5-211.6 mg/L, 114.9-523.8 mg/L, 70.3-436.4 mg/L, 6.4-33.0 mg/L, and 1.09-6.81 mg/L, respectively. In another combined sewer, the EMC of BOD, COD, SS, TN, and TP was 42.1-131.4 mg/L, 107.7-256.5 mg/L, 33.7-221.1 mg/L, 7.9-26.4 mg/L, and 1.16-3.91 mg/L, respectively. The ratio of the cumulative pollutant mass and the cumulative discharged volume determined using all parameters (BOD, $COD_{Cr}$, SS, TN, and TP) was over 1.0, which shows the first flush effect. Relationships between flow and loadings of BOD, $COD_{Cr}$, SS, TN, and TP were 0.90, 0.89, 0.88, 0.89, 0.92, respectively. Although the size of two areas was almost same, pollutant concentration and loading were different because of the amount of rainfall, rainfall intensity and basin area.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.6
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• pp.351-360
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• 2016

In regions of low-to-moderate seismicity, various types of lap splices are used for longitudinal reinforcement of columns at the plastic hinge zones. The seismic performance of such lap spliced columns, such as strength, deformation capacity, and energy dissipation, is affected by material strengths, longitudinal re-bar size, confinement of hoops, lap splice location, and lap splice length. In the present study, cyclic loading tests were performed for columns using three types of lap splices (bottom offset bar splice, top offset bar splice, and splice without offset bend). Lap splice length($40d_b$ and $50d_b$) was also considered as test parameters. Ties with 90-degree end hooks were provided in the lap splice length. The test results showed that strength, deformation capacity, and energy dissipation of columns significantly differed depending on the details and the length of lap splices. The bottom offset bar splice showed high ductility and energy dissipation but low strength; on the other hand, the top offset bar splice and the splice without offset bend showed high strength but moderate ductility and energy dissipation.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.4
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• pp.1-6
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• 2008

The burning characteristics of HTPB/AP solid propellants were measured by closed bomb of internal volume of 200 cc and 700 cc up to 30,000 psia. The burning rates of closed bomb method showed good agreement with those of strand burner method between 1,000 psia and 5,000 psia, and the sharp increment of pressure exponent(n) around 6,000 psia as a result of testing in accordance with loading densities. The burning rate measured in 200 cc and 700 cc of internal volume of closed bomb agreed well without the relation of internal volume size.

• Steel and Composite Structures
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• v.1 no.2
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• pp.187-200
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• 2001

Most of the portal frames are designed these days by the application of plastic analysis, with the normal assumption being made that the column bases are pinned. However, the couple produced by the compression action of the inner column flange and the tension in the holding down bolts will inevitably generate some moment resistance and rotational stiffness. Full-scale portal frame tests conducted during a previous research program had suggested that this moment can be as much as 20% of the moment of resistance of the column. The size of this moment of resistance is particularly important for the design of the tensile capacity of the holding down bolts and also the bearing resistance of the foundation. The present research program is aiming at defining this moment of resistance in simple design terms so that it could be included in the design of the frame. The investigation also included the study of the semi-rigid behaviour of the column base/foundation, which, to a certain extent, affects the overall loading capacity and stiffness of the portal frames. A series of column bases with various details were tested and were used to calibrate a finite element model which is able to simulate the action of the holding down bolts, the effect of the concrete foundation and the deformation of the base plate.

• Structural Engineering and Mechanics
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• v.41 no.5
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• pp.675-689
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• 2012

Most connections of steel structures exhibit flexible behaviour under cyclic loading. The flexible connections can be assumed as nonlinear rotational springs attached to the ends of each beam. The nonlinear behaviour of the connections can be considered by suitable moment-rotation relationship. Time-history analysis by direct integration method can be used as a powerful technique to determine the nonlinear dynamic response of the structure. In conventional numerical integration, the response is evaluated for a series of short time increments. The limitations on the size of time intervals can be removed by using Chen and Robinson improved time history analysis method, in which the integrated displacements are used as the new variables in integrated equation of motion. The proposed method permits longer time intervals and reduces the computational works. In this paper the nonlinearity behaviour of the structure is summarized on the connections, and the step by step improved time-history analysis is used to calculate the dynamic response of the structure. Several numerical calculations which indicate the applicability and advantages of the proposed methodology are presented. These calculations illustrate the importance of the effect of the nonlinear behaviour of the flexible connections in the calculation of the dynamic response of steel frames.

• Polymer(Korea)
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• v.33 no.6
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• pp.515-519
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• 2009

Biodegradable poly((R)-3-hydroxy butyrate) and poly(ethylene glycol) was conjugated to make amphiphilic di-block copolymer. Folate was conjugated at di-block copolymer to target the cancer cells. Copolymer was ready to form the self-assembled micelle whose size was 125~156 nm in aqueous solution. Griseofulvin as a hydrophobic drug was loaded in nanoparticles. Their loading efficiencies were 35~56%. Hydrophobic drug was continuously released for 24 h. Cell viability test showed that folate attached particles were 10% more efficient than the particles without targeting ligands.

• YAKHAK HOEJI
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• v.44 no.4
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• pp.293-299
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• 2000

Biodegradable microspheres made from poly-lactide-co-glycolide polymers have been considered as a new delivery system for single-dose vaccine. Purified tetanus toxoid (TT) was encapsulated in poly-lactide(PLA) and poly-lactide-co-glycolide (PLGA) microparticles using a solvent evaporation method in a multiple emulsion system (water-in oil-in water). The morphology of 77-loaded microparticles was spherical and the suface of them was smooth. The particle size was in a range of 2-10. Protein loading efficiency was 68-97.8%. PLGA (85:15) microparticle showed the highest efficiency. Protein release pattern was influenced by polymer molecular weight and composition. The release rate of PLA(Mw 100,000) microsphere was higher than any other microspheres. In consequence of the hydrolysis of PLGA(50:50) microspheres, environmental pH decreased from 7.4 to 5.0. The PLA, PLGA (75:25) and PLGA (85:15) microshperes showed no significant pH change. The antigenicity or n in microshperes was assayed by indirect sandwich ELISA using equine polyclonal tetanus antitoxin for capture antibody and human polyclonal tetanus antitoxin for primary antibody. The antigenicity of TT in PLA (Mw 100,000), PLGA(50:50, Mw 100,000) and PLGA (75:25, Mw 73,300) after 30 days incubation showed 54, 40.9 and 76.7%, respectively.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.306-311
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• 2003

A growing fatigue crack is known to be retarded on application of an overload cycle. The retardation may be characterized by the total number of cycles involved during retardation and the retarded crack length. The overload ratio plays an important role to influence the retardation behavior. The objective of the present investigation is to study the effect of different overload ratio on the retardation behavior. For DENT(double edge notched tension) specimens and ESET(eccentrically-loaded single edge crack tension) specimens, fatigue crack growth tests are conducted under cyclic constant-amplitude loading including a single tensile overloading with different overload ratios. The proposed crack retardation model predicts crack growth retardation due to a single tensile overloading. The predictions are put into comparison with the experimental results to confirm the reliability of this model.

• Journal of the Korean Ceramic Society
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• v.35 no.10
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• pp.1061-1069
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• 1998

The thermal instability of Al2TiO5 Ceramics was contrlled by solid solution with MgO SiO2 and ZrO2 through electrofusion in an arc furnace. The thermal expansion properties of Al2TiO5 composites show the hysteresis due to the strong anisotropy of The crystal axes of these material. These phenomena are ex-plained by the opening and closing of microcracks. The difference in microcracking temperatures e.g 587.6(ATG2), 405.9(ATG3) and 519.7$^{\circ}C$(ATG4) is caused by the difference in grain size and stabilizer type. The thermal shock behaviour under cyclic conditions between 750-1400-75$0^{\circ}C$ show no change in mi-crostructure and phase assemblage for all three stabilized specimens. After the thermal loading test at 110$0^{\circ}C$ for 100hrs. ATG1 and ATG2 materials decomposes completely to its components corundum and ru-tile in both cases. However with approximatelly 20% retention of the Al2TiO5 Thus in order to prevent decomposition of the stabilized material in the critical temperature range 800-130$0^{\circ}C$ it must be traversed within a short period of time.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.343-348
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• 2006

Number of researches on efficient terminal operation system applying RFID(Radio Frequency Identification) are on progress. However, RFID has limitations on tracking and providing accurate positions of containers. In this paper, to enhance the performance of the integrated terminal operation system, an efficient loading management of yard is proposed by applying RFID-based RTLS(Real Time Locating System) that provides real-time accurate positions of containers. We found that a group-based sequence system is more efficient than the existing individual sequence number system in the container yard. In the group-based sequence system, the containers in the same group should have similar characteristics such as port of destination(POD), size, weight, etc. In order to run this system, we have proposed the parameters to the unspecified N bytes of RFID tag which are specified in ISO 18000-7. And, this paper proposed a development of integrated operation system of container terminal using RFID for reducing the ship turnaround time in ubiquitous port environment.