• Journal of Energy Engineering
• /
• v.23 no.1
• /
• pp.90-94
• /
• 2014

Environmental qualification (EQ) for safety-related equipment is required to ensure that those equipment will perform their required function even under the harsh environment conditions arising from design basis accident in the nuclear power plant. As a part of EQ program, the room temperature analysis in case of a loss of Heating, Ventilation, and Air Conditioning(HVAC) system was carried out to ensure the operability of the safety-related equipment of a nuclear power plant randomly chosen among the Korean nuclear power plants. In this paper, this analysis was performed in the conservative perspective using GOTHIC code. The room temperature analysis includes selecting the rooms in which the safety related equipment are located but not supported by safety related HVAC and determining the temperature of the selected rooms. Target rooms for the analysis consist of W229/W237 (Aux. feedwater pump room), W232 (Aux. feedwater tank room) and W230 (Equipment passageway). The results showed the temperature range from $43^{\circ}C$ to $83^{\circ}C$, in 72 hours after a loss of HVAC. Those values are far below of generic EQ temperature($171^{\circ}C$). Therefore, it is satisfied with EQ requirement of temperature limits on safety related equipment.

• The Korean Journal of Air & Space Law and Policy
• /
• v.19 no.2
• /
• pp.199-220
• /
• 2004

The Montreal Convention which came into force on November 4, 2003 over the world, has brought a fundamental change to the scope of carrier liability and expanded the sue scope of the carrier. Not only confirms the carrier liability, it also reflects the effects of code-share. In addition to integrate the existing principles that adopted by many conventions, the Montreal Convention has systematized the unity of international air transport into a single convention. It even successfully increased the extremely low compensation amount which was pointed out as a problem in the Warsaw Convention before. The Warsaw Convention, originally stood for the carriers, began to reflect the standpoint of the passengers. The Chinese Civil Aviation Law came into force on March 1, 1996. One of the significant characteristics of the law is that, the regulation on public and private law is mixed combined. Therein, the content of carrier liability system is prescribed in Chapter 9, which is explained in detail in this study. Besides, the relationship between the Montreal Convention and China will be expounded too. So far, China ranks the 5th in RPK and the 6thin FrK. However, in spite of the high ranks, China has not yet joined this convention. This can be regarded as a serious problem. China should join it as soon as possible for a further development and deeper cooperation with the air-industry-developed countries. Once the government ratifies the Montreal Convention, it will benefit both the Chinese passengers and the airlines.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.19 no.6
• /
• pp.629-636
• /
• 2013

There is no safety evaluation index with marine accidents and information of ship's safety management result for good grasp of safety management level of shipping company and effective monitoring. In this paper, we proposed a SMEI(Safety Management Evaluation Index) for evaluation of shipping companies. The SMEI is consist of MAR(marine accidents ratio), SSMR(ship safety management ratio) and SAP(safety advantage point) through brainstorming of the expert group and AHP(analysis hierarchy process)in previous study. And weights of SMEI are calculated using experts's opinions through the Delphi method. We also verified the validity of proposed SMEI to 119 Korean shipping companies with 916 ocean-going ships of Korean flag, which grouped three part (small, mid and big) by number of ship and gross tonnage. And we found out 19 shipping companies, 8 companies in group1 & group2 respectively and 3 companies in group 3, with score below 1.0 by SMEI. In these companies, there are no marine accidents in recent 3 years and appeared low frequency remarkably in the detention and mojor non-conformity by data analysis.

• Journal of Korean Society of Steel Construction
• /
• v.27 no.1
• /
• pp.23-30
• /
• 2015

Developed in this study were Octagonal-hollow-section(OHS) struts, whose compressive strengths against flexural and local buckling is higher than H-shape or rectangular-hollow-section(RHS) struts with the same unit weight. OHS members are also advantageous in handling and storing compared to circular hollow sections(CHS). OHS members were fabricated from HR Plates by cold forming and fillet welding. 5 numbers of 20m long OHS struts were assembled, each of which consist of two 9.6m long OHS member and two end connection elements made of cast iron. The compressive strength of the OHS strut was evaluated by comparing the test results, design codes and FEM analysis each other. Test results show that all of the struts have almost same or larger compressive strength than Korean Road Bridge Design Code(KRBDC) (2012). The initial imperfections can be estimated by using measured strains and are turned out to be less than L/450 for all the struts tested. The results of FEM analysis show that the variation of initial imperfection has less effects on the compressive strength for struts with vertical surcharge than for those with self-weight only, while the strength decreases as the initial imperfection increases. As the result of this study, the allowable initial imperfection for 20m long OHS struts is recommended to be less than L/350 on job sites.

• International Commerce and Information Review
• /
• v.14 no.1
• /
• pp.345-366
• /
• 2012

The country using factoring actively today is England. The history of factoring could throw back to the Middle Ages, but modern factoring was developed in colonial age of the United States and it was known throughout England in 1960s. At the beginning, it performed mercantile agent who works in local area in order to get rid of uncertainty and inconvenience of a distant trade, but it was getting developed into a today's factoring system which focusing more on financial function. The factoring is called 'account receivable financing' in the United States and it is started out as sales agent and getting developed to 'del credere agent' who guarantee the payment. The activities of factors have been expanded to not only consignment sale and payment guarantees but also advance financing service. However, at the end of the 19th century, the direct sales(direct marketing) was expanded by the development of telecommunication and transportation technology, and then the marketing service by factor was degraded, but the collection of payment and advance finance had been maintained until now and developed into today's factoring system. Especially, the establishment of Uniform Commercial Code in 1931 had formed the basis for activating factoring in the United States through preparing a legal basis of factoring. Due to changes of international trade environment, most of commercial bank in Korea have to deal with export factoring as a trade finance service and it is desirable to specialize as a financing for small and medium company.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.3
• /
• pp.197-209
• /
• 2018

In this study, numerical analyses on Quad Tilt Rotor(QTR) are carried out to investigate the interference effect of components and effect of operating condition during forward flight. Actuator Surface Method(ASM) which is implemented in an open source CFD code, OpenFOAM, is used to calculate the flow field around QTR with high computational efficiency. The lift of the front and rear wing is found to increase or decrease depending on the rotation direction of the rotor. At the rear wing, the interference effects of the front and rear rotor appear as a combined manner. Performance change due to the phase difference is found to be insignificant. For both rotors, the locally higher thrust is generated by the blockage effect of the wing. The interference effect of wake from the front nacelle contributes to higher local thrust for the rear rotor compared to the front rotor. And it is observed that the amplitude of thrust oscillation can decrease depending on the phase difference between the rotors. Aerodynamic performances of both rotors and the entire aircraft were compared and analyzed for various operating conditions.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.28 no.6
• /
• pp.332-349
• /
• 2016

OLAFOAM is the powerful CFD code and is an expanded version of $OpenFOAM^{(R)}$, for wave mechanics simulation. The $OpenFOAM^{(R)}$ does provide many solvers to correspond to each object of the numerical calculation in a variety of fields. OLAFOAM's governing equation bases on VARANS (Volume-Averaged Reynolds-Averaged Navier-Stokes) equation, and the finite volume method is applied to numerical techniques. The program is coded in C++ and run on the Linux operating system. First of all, in this study, OLAFOAM was validated for 1) wave transformation inside porous structure under bore and regular wave conditions, 2) wave transformation by submerged breakwater under regular wave condition, and 3) regular wave transformation and resultant vertical velocity distribution under current by comparison with existing laboratory measurements. Hereafter, this study, which is almost no examination carried out until now, analyzed closely variation characteristics of water surface level, wave height, frequency spectrum, breaking waves, averaged velocity and turbulent kinetic energy around porous submerged breakwater in the wave and current coexisting field for the case of permeable or impermeable rear beach. It was revealed that the wave height fluctuation according to current direction(following or opposing) was closely related to the turbulent kinetic energy, and others.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.16 no.5
• /
• pp.19-28
• /
• 2012

In this study, cause of longitudinal crack which is found on duct slab of road tunnel is studied. In-depth investigation, such as visual inspection, non-destructive testing and geometrical surveying of duct slab, is carried out. In order to perform cause analysis, the investigated results are compared to the results of numerical analysis. Many factors, which cause longitudinal crack, are classified as constrained condition of the duct slab, location of the rebar, temperature, shrinkage and so on. According to the classified causes of longitudinal crack, numerical analysis is performed considering construction stage of the tunnel lining. Especially, in order to predict shrinkage stain due to discrepancy of curing date, ACI-209 model, KCI structural design code and other researcher's shrinkage test results are compared. The results show that shrinkage strain is one of the main factors causing longitudinal crack. Other investigated tunnels are classified along with the construction method of duct slab and patterns of cracks. As a result, improving ways to construct duct slab are suggested.

• Journal of Aerospace System Engineering
• /
• v.12 no.2
• /
• pp.7-14
• /
• 2018

In this study, a new check valve was studied to improve the load pressure of a brake system with a small piezoelectric-hydraulic pump. During the pressurization process, the steady-state pressure at the load is affected by the ratio of the cross-sectional area of the check valve the chamber pressure and load pressure. Since the flow path cover of the check valve is made wider than the cross-sectional area of the output flow to prevent backflow, a method of reducing the area ratio is proposed for a higher load pressure by mounting an additional mass to a thin plate spring type check valve. To identify the effect of mounting an additional mass to the existing check valve on the load pressure, a simple brake system with a small piezoelectric-hydraulic pump was modeled using a commercial code AMESim. The AMESim modeling was verified by comparing the simulation results with the experimental results of the pump the existing check valve. The additional mass was added to the verified AMESim modeling and higher load pressure was able to be obtained through simulation. The 35% performance improvement in load pressure identified by carrying out pressurization test of the brake system after adopting the new check valve the small piezoelectric-hydraulic pump.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.1A
• /
• pp.133-142
• /
• 2006

This paper evaluates the moment equations in the 2000 Canadian highway bridge code (CHBDC) for soil-metal box structures, which are applicable to the span less than 8 m. Finite element analyses carried out for soil-metal box structures having spans of 3-12 m using the deep corrugated metal plates under three construction stages; backfill up to the crown, backfill up to the cover depth, and live loading. The coefficients of moment equations are newly proposed based on the results of numerous finite element analyses considering various design variables, such as span length, soil depth, backfill conditions. The validity of the proposed coefficients in the moment equations of the 2000 CHBDC is investigated by the comparison with the existing coefficients and numerical results of finite element analyses. The comparisons show that the moments of the 2000 CHBDC give good predictions for the span less than 8m, but underestimate for the span greater than 8m, whereas the proposed moments give good estimates of numerical results for the spans of 3-12 m. In addition, this study suggests the use of high strength steel to satisfy the requirement of design bending strength for the span greater than 8 m.