• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.249-258
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• 2005

A two-column six-step pressure swing adsorption(PSA) process was to study separation of hydrogen from hydrogen and methane($60_{vol}%/40_{vol}%$) binary system onto activated carbon adsorbent. The effects of the feed gas pressure, the feed flowrate and the P/F(purge to feed) ratio on the process performance were evaluated. The cyclic steady-states of PSA process were reached to after 15 cycles. $H_2$ purity increases according as the P/F ratio and pressure increase and the feed flow rate decreases; however, $H_2$ recovery shows an opposite phenomena to the purity. PSA process simulation studied to find optimum operation condition. In the results, 22 LPM feed flowrate, 11 atm adsorption pressure and 0.10 P/F ratio might be optimal values to obtain more than 75% recovery and 99% purity hydrogen. In this study was non-isothermal and non-adiabatic model considering linear driving force(LDF) model and Langmuir-Freundlich adsorption isotherm considered to compare between prediction and experimental data.

• Proceedings of KOSOMES biannual meeting
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• 2007.05a
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• pp.203-210
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• 2007

This paper treats optimal route safety assessment system at seaway based on weather forecasting data through INMARSAT. Since early times, captain have been sailing to select the optimum route considering the weather, ship loading status condition and operational scheduling empirically. However, it is rare to find digitalized onboard route support system whereas weather facsimile or wave and swell chart are utilized for the officer, based on captain's experience. In this paper, optimal route safety assessment system which is composed of voyage efficiency and safety component is introduced. Optimum route minimized ETA(estimated time of arrival) and fuel consumption that shipping company. and captain are requiring to evaluate for efficient voyage considering speed loss and power increase based on wave added resistance of ship. In the view point of safety, seakeeping prediction is performed based on 3 dimensional panel method Basically, the weather forecast is assumed to be prepared previously in order to operate this system.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.234-243
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• 1992

Fatigue crack initiation life has a wide scatter and this makes the fatigue design of structural members difficult. In order to make the fatigue life distribution clear, it is required to prepare a large number of specimens and repeat the fatigue tests under the same loading condition. Such fatigue tests usually take much time and cost. In this study, a fatigue testing method using a multi-notched test specimen for the purpose of estimating the distribution function of fatigue crack initiation life by small number of fatigue tests is used. The purpose of this study is to verify the above fatigue testing method of a multi-notched specimen by using Bayesian reliability analysis, Least square method and Skewness method for the determination of unknown Weibull parameters. The multi-notched specimen is a specimen in which several tens of statistically identical notches are prepared.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.6
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• pp.383-390
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• 2019

A helideck is one of the essential structures in offshore platforms for the transportation of goods and operating personnel between land and offshore sites. As such, it should be carefully designed and installed for the safety of the offshore platform. In this study, a structural design optimization method for a lightweight offshore helideck is developed based on a genetic algorithm and an attainable design set concept. A helideck consists of several types of structural members such as plates, girders, stiffeners, trusses, and support elements, and the dimensions of these members are typically pre-defined by manufacturers. Therefore, design sets are defined by collecting the standard section data for these members from the American Institute of Steel Construction (AISC), and integer section labels are assigned as design variables in the genetic algorithm. The objective is to minimize the total weight of the offshore helideck while satisfying the maximum allowable stress criterion under various loading conditions including self-weight, wind direction, landing position, and landing condition. In addition, the unity check process is also utilized for additional verification of structural safety against buckling failure of the helideck.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.3
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• pp.227-233
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• 2008

Recently, the transport quantity of goods between South and North Korea is rising rapidly by increasing of economical exchange between South and North Korea and growth of Gaeseoung industrial complex. In addition to a land transportation route, it is necessary to secure various logistics and transportation route for freight transportation between Incheon and Gaesung. In this paper, we investigated a construction of barge transportaion system between Incheon and Gaesung. The barge transportation system which has many merits such as a little initial investment and convenience of harbor loading/ unloading has been also used to transport freight widely in the EU and USA. Firstly, we investigated barge transport route, marine freight and barge fleet which consists of barge and pusher between Incheon and Gaesung. And next, we designed hull form and general arrangement of a barge and pusher based on shipping service condition, barge fleet, etc. Finally, a construction plans of barge transport system such as a operation of shipping service, berthing facilities, logistics center, intermodal transport are investigated.

• Korean Journal of Materials Research
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• v.11 no.6
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• pp.465-471
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• 2001

The effect of sintering condition on the mechanical properties and leachability of polydispersed ceramic core body made by gel-casting process in aqueous medium have been investigated. The polydispersed ceramic slip that has low viscosity($\leq$1000cP, at 1000cP (at $50sec^{-1}$ ) and high solid loading(50vo1%) was obtained. The green bodies were fabricated through casting and gelation at room temperature followed by drying at $25^{\circ}C$for 48hrs under relative humidity of 80%. Crack-free green body was successfully fabricated through the above process. The strength at room temperature, apparent bulk density, and shrinkage of the ceramic core body increased propotionally with increasing sintering temperature(1100~150$0^{\circ}C$). However, porosity of the ceramic core body showed relatively low vague. Leaching rate of sintered core body increased with increasing porosity of the sintered body, and was significantly dependent upon the concentration of alkali caustic solution at the same leaching temperature.

• Journal of the Korean Geotechnical Society
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• v.28 no.9
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• pp.57-67
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• 2012

In the design for piled rafts, the load capacity of the raft is in general ignored and the load capacities of pile are only considered for the estimation of the total load carrying capacity of the piled raft. The axial resistance of piled raft is offered by the raft and group piles acting on the same supporting ground soils. As a consequence, pile - soil - raft and pile - soil interactions, occurring by stress and displacement duplication with pile and raft loading conditions, acts as a key element in the design for piled rafts. In this study, a series of centrifuge model tests has been performed to compare the axial behavior of group pile and raft with that of a piled raft (having 16 component piles with an array of $4{\times}4$) at the stiff and soft clays. From the test results, it is observed that the interactions of piles, soil, and raft has little influences on the load capacities of piles and raft in piled rafts compared with the load capacities of group piles and raft at the same clay soil condition.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.459-465
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• 2012

This study analyzed the effect of semi-rigid rafter-purlin cross-linking connection and driven steel pipe base on the static behavior of plastic greenhouse (PG). To promote the time and cost efficiency of the assembly process, each cross-linking connections of space arch type grid that consists of rafter and purlin is linked with steel-wire buckles, and each end of the rafters was driven directly to the ground to support the PG structure. However, in the design process, cross-linking connections and bases are idealized by being categorized as fully rigid or frictionless pinned, which does not appropriately reflect actual conditions. This study takes a full-scale loading test of PG and analyzes the effect of member cross-linking connections and driven steel pipe base on the behavior of a structure. The analysis provided a basis for determining the rigidity factor of member cross-linking nodes needed for finite element analysis, and the reliability of the result regarding the static behavior of PG.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.198-208
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• 2011

When a structure which has relatively low load constructs on soft clay, the bearing capacity of the ground will be improved by sand overlying clay. In this condition, verifying the bearing capacity is difficult from the P.B.T etcetera in the in-situ. So, it is needed to estimate precise bearing capacity in the design process. In this study, 2-dimensional chamber tests and FEM analyses are conducted to evaluate behavior of bearing capacity for shallow foundations on a sand overlying clay. Because depth ratio H/B and bearing capacity ratio $q_c/q_s$ are selected as main factors, height of a sand, undrained shear strength of a clay and width of a loading are designated as variables. Results from chamber tests are very similar with those of FEM analyses. And it shows that punching shear mechanism is more suitable than the equation of Okamura et al.(1998). To make continual application of load spread mechanism, the equivalent load spread angle is proposed for H/B and $q_c/q_s$. Also, the linear regression equation of critical depth ratio Hf is suggested for $q_c/q_s$.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.58-63
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• 2009

Dissolved air flotation (DAF) process is generally considered more effective than sedimentation process in raw water containing algae, humus materials, and low density particles. This study presents the treatment efficiencies by the coagulation and flocculation conditions at a drinking water treatment plant using a laboratory tester and the full scale DAF pump system. The full scale DAF pump system (F-DAF) in this study had a capacity of 5,000 $m^3$/d and a hydraulic surface loading of 10 m/hr. F-DAF in D drinking water treatment plant was continuously operated to determine the operational performance and pretreatment (mixing and coagulation) conditions. Results in the laboratory experiment showed that the optimum coagulant (PSO-M) doses required to 2.7~4.5 mL/$m^3$/NTU with raw water turbidity from 13.8 NTU to 56.3 NTU. F-DAF in the optimum coagulant dosage could be operated in effluent turbidity of 1 NTU or below for a month.