• Journal of the Society of Naval Architects of Korea
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• v.40 no.6
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• pp.20-29
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• 2003

When Arctic offshore development in the 1970's first led to the consideration of ice capable tankers, there was a high level of uncertainty over design requirements for both safety and ship performance. Also here was a lack of reliable methods to evaluate design proposals. Since that time, improved understanding of the ice environment has raised the confidence of design specifications. Parallel developments have resulted in a suite of engineering tools for ship performance evaluation at the design stage Recent development of offshore and near shore oil and gas reserves in several countries together with economic studies of increased transportation through the Russian Arctic has newly introduced the interest in ice capable tanker design. in response, Samsung Heavy Industries (SHI) applied its experience in tanker design and construction to the design of a specialized tanker with ice capability. SHI produced two prototype hull designs for further study. The performance of both hulls and of the propellers was evaluated at the Institute for Marine Dynamics (IMD) in St. John's, Newfoundland This paper discusses the development of the design, describes the model experiments to determine performance and variations, and presents the results.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.1
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• pp.27-36
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• 2011

In the proposed paper numerical calculations are carried out using two versions of a three-dimensional, timedomain panel method developed by the group of Prof. P. Sclavounos at MIT, i.e. the linear code SWAN2, enabling optionally the use of the instantaneous non-linear Froude-Krylov and hydrostatic forces and the fully non-linear SWAN4. The analytical results are compared with experimental results for three hull forms with increasing geometrical complexity, the Series 60, a reefer vessel with stern bulb and a modern fast ROPAX hull form with hollow bottom in the stern region. The details of the geometrical modeling of the hull forms are discussed. In addition, since SWAN4 does not support transom sterns, only the two versions of SWAN2 were evaluated over experimental results for the parent hull form of the NTUA double-chine, wide-transom, high-speed monohull series. The effect of speed on the numerical predictions was investigated. It is concluded that both versions of SWAN2 the linear and the one with the non-linear Froude-Krylov and hydrostatic forces provide a more robust tool for prediction of the dynamic response of the vessels than the non-linear SWAN4 code. In general, their results are close to what was expected on the basis of experience. Furthermore, the use of the option of non-linear Froude-Krylov and hydrostatic forces is beneficial for the accuracy of the predictions. The content of the paper is based on the Diploma thesis of the second author, supervised by the first one and further refined by the third one.

• Journal of Power System Engineering
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• v.17 no.5
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• pp.58-63
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• 2013

In this study, the effect of deep ocean condenser inlet temperature ($T_{DOI}$), condenser inlet pressure ($P_{cond,in}$), and thermal diffusivity on system efficiency of some selected refrigerants was analyzed using HYSYS. The proposed DOTEC cycle is similar to the reheat Rankine cycle but eliminates irreversibilities by bleeding a fraction of the steam between certain stages of the turbine. The evaporator inlet mass flow rate, inlet temperature of turbine 1, turbine efficiency and inlet and outlet temperature of heat source were imposed. The working fluids considered are sorted in ascending order of their molecular weights as R717, R600a and R152a. Results indicated that a fluid with a lower boiling point temperature like R717 needs a corresponding high heat source and/or evaporator inlet pressure. Also, the response of thermal diffusivity closely follows the change in TDOI as an increase in $T_{DOI}$ increases $P_{cond,in}$ which reduces thermal diffusivity and system efficiency. Furthermore, the fluid with the nominal boiling point temperature has the highest efficiency with efficiency decreasing with an increase in TDOI.

• The Journal of Korean Medicine
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• v.19 no.2
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• pp.86-99
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• 1998

Antiallergic action and the effect on normal immune function of an oriental medical prescription Gegangjochohwangsinbutang (GJHB) water extract were examined in several experimental models. GJHB water extract at 600-1,800 mg/kg/day administered orally for one week significantly recuded the passive cutaneous anaphylaxis in rats in a dose-dependent manner. Whereas the extravasation induced by intradermal leukotriene D4 in rats was significantly inhibited by GJHB water extract at 600-1,800 mg/kg/day, po, for one week, but that by histamine or serotonin was not influenced. In a rat asthma model, the delayed airway resistance in ovalbumin-induced asthmatic response was significantly attenuated by GJHB water extract of 1,800 mg/kg/day, po, administered for one week. It was also found that GJHB water extract at 1 mg/kg concentration in vitro relaxed the isolated uinea pig trachea contracted by leukotrien D4, but not that by histamine. The above findings indicate that GJHB water extract can ameliorate the adverse effect of type Ⅰ allergy such as asthma. This pharmacological action seems to derive from an inhibition of GJHB water extract on leukotriene D4-related physiological change.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.1
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• pp.1-14
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• 2018

In this study, we develop and propose damping correction factors for the Korean standard design spectra. The newly proposed Korean standard design spectra has been given only for 5% damping ratio. But in practice, engineers need design spectra for damping values other than 5%. To obtain design spectra for various damping values from the standard spectra, damping correction factors are derived. These factors modify the shape of design spectra in accordance with the damping ratio. Response spectra for various damping values are calculated from the earthquake records that had been used to calculate standard design spectra. They consist of 55 records from 18 earthquakes occurred in overseas intraplate regions and Korea. The regressed spectra for the damping values ranging from 0.5% to 50 % are compared with standard spectra at three regions acceleration, velocity and displacement sensitive regions. The regression analysis of these data rendered formula for damping correction factors. Finally, a single formula for damping correction factors is recommended that is valid for both horizontal and vertical design spectra and that is applicable to the entire range of periods. One thing to note that recommended damping correction factors is valid for the design spectrum of the rock grounds because the design spectra was developed based on the earthquake records of the rock ground.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.4
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• pp.319-327
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• 2017

In this study, characteristics of seismic behaviors of offshore wind turbine systems using concrete-suction-type supporting structures are investigated. Applying hydrodynamic pressure from the surrounding sea water and interaction forces from the underlying soil to the structural system which is composed of RNA, the tower, and the supporting structure, a governing equation of the system is derived and its earthquake responses are obtained. It can be observed from the analysis results that the responses are significantly influenced by soil-structure interaction because dynamic responses for higher natural vibration modes are increased due to the flexibility of soil. Therefore, the soil-structure interaction must be taken into consideration for accurate assessment of dynamic behaviors of offshore wind turbine systems using concrete-suction-type supporting structures.

• The Journal of Fisheries Business Administration
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• v.30 no.1
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• pp.1-29
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• 1999

When the international fisheries order changes following the UN Law of the Sea, the new regional fisheries order is forming among East North Asian states and era of Economic Zones is really coming. In those changes of foreign and domestic fisheries environment, to maintain sustainable growth of the industry in 21st century the North East Asian states plot adjustments to fisheries management, such as introduction of the TAC system and others. The TAC seems to be an appropriate systematic response especially because traditional functions of fisheries management have already demonstrated their limits in regards to fisheries sustainable development. Introduction of the TAC to the North East Asian fisheries not only resolves the inability of traditional fisheries management to develop the industry consequently, but also strengthens the EEZ and existing marine management systems. However, the TAC was born by thewestern industrial mentality, still contains persistent mistakes and is difficult to change. Therefore, its introduction to and implication in North East Asian region might cause numerous problems. From this point of view, introduction of the TAC system will disregard peculiarities of North East Asian fisheries, so main efforts should be concentrated on improving the functions of existing system via consecutive step-by-step approach. In addition, the TAC should be grafted into the existing fisheries system through cooperative management system, creating stable systematic ground and considering scientific and fisheries motives. Especially, TAC system, unlike the traditional fisheries' management system, is scientific, being systematically developed one, and needs to be gradually installed, considering its systematic character. Therefore, the TAC should better be introduced by systematic and scientific approaches, paying more attention to strengthening the existing fisheries system, but not immediately and in the form it is right now. Concluding, introduction of the TAC can not be made considering the outward factors deriving from the UN Law of the Sea without corrections.'h overcome limitations and ineffectiveness of traditional fisheries, most efforts should be concentrated on basic revision of 21st centuries' fisheries and strengthening the functions of traditional fisheries aimed to develop the leading business of marine industries.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.791-798
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• 2016

In this study, numerical simulations on the effects of bilge keel on roll motion were conducted. The numerical simulations were performed on a 110 m class PSV using the commercial viscous flow analysis software Star-CCM+. Before conducting the study on the 110 m class PSV, an additional simulation of DTMB 5512 was performed and compared with the experimental results to validate the feasibility of the numerical simulation. In the simulation on PSV, a nondimensional damping coefficient was calculated using a free roll decay simulation, and the response amplitude operator (RAO) for the roll motion was calculated with a nondimensional damping coefficient at two conditions (with/without bilge keel).

• The Journal of the Acoustical Society of Korea
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• v.34 no.4
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• pp.295-302
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• 2015

Acoustic channels are characterized by long multipath spreads that cause inter-symbol interference. The way in which this fact influences the design of the receiver structure is considered. To satisfy performance and throughput, we presented consecutive iterative BCJR (Bahl, Cocke, Jelinek, Raviv) equalization to improve the performance and throughput. To achieve low error performance, we resort to powerful BCJR equalization algorithms that iteratively update probabilistic information between inner decoder and outer decoder. Also, to achieve high throughput, we divide long packet into consecutive small packets, and the estimate channel information of previous packets are compensated to next packets. Based on experimental channel response, we confirmed that the performance is improved for long length packet size.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.6
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• pp.692-710
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• 2018

The Three-dimensional (3-D) dynamical behaviors of a fluid-conveying pipe subjected to vortex-induced vibration are investigated with different internal flow velocity ${\nu}$. The values of the internal flow velocity are considered in both subcritical and supercritical regimes. During the study, the 3-D nonlinear equations are discretized by the Galerkin method and solved by a fourth-order Runge-Kutta method. The results indicate that for a constant internal flow velocity ${\nu}$ in the subcritical regime, the peak Cross-flow (CF) amplitude increases firstly and then decrease accompanied by amplitude jumps with the increase of the external reduced velocity. While two response bands are observed in the In-line (IL) direction. For the dynamics in the lock-in condition, 3-D periodic, quasi-periodic and chaotic vibrations are observed. A variety of CF and IL responses can be detected for different modes with the increase of ${\nu}$. For the cases studied in the supercritical regime, the dynamics shows a great diversity with that in the subcritical regime. Various dynamical responses, which include 3-D periodic, quasi-periodic as well as chaotic motions, are found while both CF and IL responses are coupled while ${\nu}$ is beyond the critical value. Besides, the responses corresponding to different couples of ${\mu}_1$ and ${\mu}_2$ are obviously distinct from each other.