• 대한조선학회논문집
• /
• 제56권3호
• /
• pp.263-272
• /
• 2019

The aim of this study is to develop a rapid calculation technique of the residual strength in order to prevent sequential events under grounding accidents. Very Large Crude-Oil Carrier (VLCC), Suezmax, and Aframax double hull oil tankers carrying large quantities of crude oil were selected for target structures. The rock geometries are chosen from the published regulation by Marine Pollution Treaty (MARPOL) of the International Maritime Organization (IMO). Oceanic rocks as the most frequently encountered obstruction with ships are applied in this work. Damage condition was predicted using ALPS/HULL program based on grounding scenario with selected parameters, i.e. depth of penetration, damage location and tanker type. The results of the scenarios are quantified to form an empirical formula which can evaluate the residual strength. The proposed formula is validated by applying a series of random grounding scenarios.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 1998년도 유체기계 연구개발 발표회 논문집
• /
• pp.91-96
• /
• 1998

The broadband noise generated aerodynamically from a two-bladed axial flow fan has been measured and compared to the result of a self-noise prediction method. The prediction scheme is based on the experimental data set acquired from a series of aerodynamic and acoustic tests of two and three-dimensional airfoil blade sections. For low blade loading case the comparison showed a reasonably good agreement, but as the loading becomes larger the empirical formula overpredict the sound pressure level at high frequency range. This is probably due to the use of stationary wing data for the prediction of rotating blade case, which will be quite different in their vortex strength at the blade tip.

• International Journal of Concrete Structures and Materials
• /
• 제3권2호
• /
• pp.111-117
• /
• 2009

Concrete columns reinforced with Fibre Reinforced Polymer (FRP) rebar have been increasingly used in civil engineering applications, while the research on fire resistance of such structural members is still very limited. In this paper, attempts are made to predict temperature distribution and mechanical performance of FRP rebar reinforced concrete columns in fire. The effect of concrete cover and section size on fire resistance time is studied by the finite element method. Based on a parametric study, a simple empirical formula to predict fire resistance time is proposed for possible adoption in fire resistance design.

• 한국세라믹학회지
• /
• 제55권1호
• /
• pp.67-73
• /
• 2018

A poled lead zirconate titanate (PZT) cube specimen that is switched by an electric field at room temperature is subject to temperature increase. Changes in polarization and thermal expansion coefficients are measured during temperature rise. The measured data are analyzed to obtain changes in pyroelectric coefficient and strain during temperature change. Empirical formulae are developed using linear or quadratic curve fitting to the data. The nonlinear behavior of the materials during temperature increase is predicted using the developed formulae. It is shown that the calculation results can be compared successfully with the measured values, which proves the accuracy and reliability of the developed formulae for the nonlinear behavior of the materials during temperature changes.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2016년도 학술발표회
• /
• pp.193-193
• /
• 2016

In past decades beach erosion has been remarkably severe along coasts of different parts of the world, so that distinct types of coastal protective measures have been implemented; seawalls, wave-dissipating breakwaters, groins, artificial headlands or detached breakwaters have been constructed. In recent years, at Bongpeong beach, South Korea, an artificial headland was constructed to stop the beach erosion. The structure resulted in severe beach erosion of the adjoining places. In order to stop the consequences, another headland was constructed at some distance, but the construction of double headland did not prevent the erosion significantly. This paper focuses on the accurate design of the artificial double headland construction. The study presents the application of equilibrium shoreline empirical formula of parabolic type to estimate the equilibrium stages of the artificial double headland beaches and an analytic solution is presented in the present study. The research has solved the empirical formula of parabolic type to find the optimum result by considering the essential parameters that influence the erosion after the construction of double headland.

• 대한조선학회논문집
• /
• 제55권4호
• /
• pp.313-320
• /
• 2018

As ships operating on the Arctic route are exposed to various ice environments such as level ice, pre-swan, pack ice, ice ridge and brash ice, it is essential to estimate the ice resistance according to the ice environment. Methods for estimating the ice resistance include a method using mathematical model, numerical simulation, and a method using empirical formula. In this study, empirical formulas are used to estimate the ice resistance. The purpose of this study is to develop the ice resistance and attainable speed estimation program(I-RES) for brash ice. To develop the Brash ice attainable speed estimation algorithm, the environmental characteristics of the brash ice were analyzed, and the results of I-RES were evaluated by comparing the model test results of brash ice. The accuracy of I-RES for brash ice is around 20% in this study but it will be more developed near future with accumulating more model test results and calculation results.

• 대한한의정보학회지
• /
• 제16권2호
• /
• pp.51-88
• /
• 2010

An empirical formula that has been empirically shown to be effective for a particular condition can be said to add medical materials to an exciting formula or to make a new prescription by Korean medical doctors' empirical clinic. This dissertation aims to study the prescriptions according to A Confidential Document of A Distinguished Medical Family and to contribute to the development of Korean medicine. A Confidential Document of A Distinguished Medical Family is a medicinal recipe that is an heirloom of the Gyeongju Kim family for the eighth generation. And the date and the writer of the book are unknown. The contents of the book consist of 18 parts and are made up of about 300 medical recipes. Of these, 153 formulas and indications of roundworm, cholera, puffy swelling, abdominal distension, phlegm-rheum, woman, child, summerheat, dryness-heat, eye, and blood are found in the book. From among these, 26 formulas are directly quoted out of The Precious Mirror of Oriental Medicine, 93 formulas are adjusted in proportion or combined and 34 formulas are empirical ones. By the parity of reasoning of the above, I think that this book was published after The Precious Mirror of Oriental Medicine.

• 대한조선학회논문집
• /
• 제55권4호
• /
• pp.350-360
• /
• 2018

Analysis of ship's manoeuverability in shallow water is an important task from the perspective of the vessels' navigational safety. Since the number of ships operated in restricted water has increased due to the enlargement of vessels and ships represent different characteristics of the manoeuverability when operated in shallow and deep water, it is significant to evaluate ship manoeuverability at initial design stage. At the initial stage of design, the estimation of manoeuverability is generally performed with hydrodynamic coefficients estimated based on empirical formula. However, the accuracy of estimating hydrodynamic coefficients by the empirical formula in shallow water is poor compared to that in deep water. Therefore, the error in the estimation of manoeuverability increases in shallow water. In this study, CFD is proposed to improve the accuracy of manoeuverability in shallow water at the initial design stage and hydrodynamic coefficients were obtained based on PMM test in shallow water. Furthermore, the ship manoeuverability was estimated both the proposed strategy and the empirical formula. At last, validity of the proposed strategy using CFD for the estimation of manoeuverability was confirmed by comparison with the manoeuverability estimation results from model test.

• Journal of Radiation Protection and Research
• /
• 제11권1호
• /
• pp.22-28
• /
• 1986

우라늄의 용존농도(溶存濃度)와 토륨의 용존농도(溶存濃度) 및 질산(窒酸)의 노르말농도(濃度)가 서로 다른 여러가지 질산(窒酸) 우라늄-질산(窒酸)토륨 혼합용액(混合溶液)을 만들어 피크노메타(pycnometer)로서 그 밀도를 측정한 후 우라늄의 용존농도, 토륨의 용존농도 및 질산의 노르말농도만의 함수로서 물함량(含量)을 결정할 수 있는 실험식을 유도하였다. 그 결과 유도된 실험식은 $W=1.0-0.358\;C_u-0.4538\;C_{Th}-0.0307\;H^+$로서 여기에서 $W,\;C_u,\;C_{Th}$ 및 $H^+$은 각각 혼합용액중(混合溶液中)의 물함량(含量)(g/cc), 우라늄의 용존농도(溶存濃度)(g/cc), 토륨의 용존농도(溶存濃度)(g/cc) 및 질산(窒酸)의 노르말농도(濃度)를 나타낸다. 유도된 실험식에 의하여 산출된 물함량을 Bouly 등(等)의 방법으로 계산한 결과치(結果値)와 비교하였는데 그 차이는 2.7%이하인 것으로 나타났다.

• 한국습지학회지
• /
• 제16권1호
• /
• pp.125-137
• /
• 2014

본 연구에서는 국내 기존 도달시간 산정방법에 있어 Kraven(II)는 경사구간별 3가지 유속을 제시하고 있으므로 해당 유역특성이 충분히 반영되지 못하고 있다. 이에 최근 "설계홍수량 산정요령, 2012. 국토해양부"에서 제안한 보완된 연속형 Kraven 경험식은 완경사부와 급경사부의 유속을 보완하였으며, 평균유속이 최소유속 1.6m/s에서 최대유속 4.5m/s의 범위내의 연속성의 유속을 나타내고 있어서 현실적으로 타당한 범위를 가지며, 도달시간도 매우 합리적인 결과를 나타내고 있으므로 기존의 불연속의 문제나 매우 완만한 경우와 급한 경우의 적용성에도 매우 우수한 것으로 나타나고 있다. 본 연구에서는 도달시간 산정방법에 있어 기존 Kraven(II) 경험식과 보완된 연속형 Kraven 경험식에 따른 수문곡선의 변화양상을 살펴보았으며, 동화천, 매호천, 욱수천, 금포천에 대해서 각 해당 유역특성을 고려하여 단위도법-도달시간 산정방법에 따른 홍수유출모의결과를 비교분석하였다.