• 대한조선학회논문집
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• 제55권1호
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• pp.45-55
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• 2018

Concerns are emerging in marine industry on the additional fatigue damages induced by hydroelasticity, and large container carriers, among others, are considered to be susceptible to this hydroelastic response due to its large size, deck openings and high speed. This study focuses on the fatigue damage estimation of 9,400TEU container carrier based on the full scale measurement data via long-base strain gage installed on the ship. Some correlation analyses have been also done to check whether there was significant torsional response during the voyage. Direct cycle counting method was used to derive stress histogram and the long-term fatigue damage was estimated based upon that analyzed data. It turned out that the fatigue damage of this particular ship during the measurement period increased by more than 60% due to the hydroelastic response of the hull, and main contribution is considered to come from vertical bending mode.

• 동아시아식생활학회지
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• 제20권2호
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• pp.272-278
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• 2010

Various quality attributes were determined in muffins prepared using purple-colored sweet potato flour. Height of control muffins was 5.8 cm lease clarify. Height decreased with increasing quantity of sweet potato powder. Muffin volume was not appreciably affected. Moisture of control muffins was 21.84. The moisture value decreased with increasing quantity of sweet potato powder. Scanning electron microscopy examination revealed thick cell wall and rough stoma in muffins prepared with purple-colored sweet potato powder. The amount of gluten decreased as the quantity of purple-colored sweet potato powder increased. Brightness L values significantly changed as the amount of powder increased, indicative of a progressively darker product. Red index a values decreased as the quantity of purple-colored sweet potato powder increased. Yellow index b values decreased significantly in the control group as powder quantity increased. Hardness increased with increasing addition of powder, but no significant difference was evident between 6% and 9% amended samples. There were also no significant differences in springing in samples containing 3% and 6% powder but 9% powder produced a significant difference. Cohesiveness did not differ in unamended samples and samples amended with 3% and 9% powder, however a significant difference was evident in samples prepared with 6% powder. Gumminess and chewiness increased as the quantity of purple-colored sweet potato powder increased. Color did not differ appreciably in sample prepared with 3% and 9% Sample prepared with 3% additives showed the highest What? Color score? Something else? Please clarify with 6.4. There was no significant difference of the flavor in samples prepared with 3% and 6% powder, or in taste among samples prepared 3%, 6%, and 9% powder. No significant differences in texture were evident in any sample Overall acceptability was highest (7.2) in samples prepared with 3% of purple-colored sweet potato.

• 대한조선학회논문집
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• 제51권2호
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• pp.122-129
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• 2014

Identification of the whipping response out of the combined wave-vibration response of a flexible sea going vessel is one of the most interesting research topic from ship designer's point of view. In order to achieve this goal, a novel methodology based on the wavelet cross-correlation technique was proposed in this paper. The cross-correlation of the wavelet power spectrum averaged across the frequency axis was introduced to check the similarity between the combined wave-vibration response and impulse response. The calculated cross-correlation of the wavelet power spectrum was normalized by the auto-correlation of the each spectrum with zero time lag, eventually providing the cross-correlation coefficient that stays between 0 and 1, precisely indicating the existence of the impulse response buried in the combined wave-vibration response. Additionally, the weight function was introduced while calculating the cross-correlation of the two spectrums in order to filter out the signal of lower frequency so that the accuracy of the similarity check becomes as high as possible. The validity of the proposed methodology was checked through the application to the artificially generated ideal combined wave-vibration signal, together with the more realistic signal obtained by running 3D hydroelasticity program WISH-Flex. The correspondence of the identified whipping instances between the results, one from the proposed method and the other from the calculated slamming modal force, was excellent.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.1130-1147
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• 2014

Large size ships have a very flexible construction resulting in low resonance frequencies of the structural eigen-modes. This feature increases the dynamic response of the structure on short period waves (springing) and on impulsive wave loads (whipping). This dynamic response in its turn increases both the fatigue damage and the ultimate load on the structure; these aspects illustrate the importance of including the dynamic response into the design loads for these ship types. Experiments have been carried out using a segmented scaled model of a container ship in a Seakeeping Basin. This paper describes the development of the model for these experiments; the choice was made to divide the hull into six rigid segments connected with a flexible beam. In order to model the typical feature of the open structure of the containership that the shear center is well below the keel line of the vessel, the beam was built into the model as low as possible. The model was instrumented with accelerometers and rotation rate gyroscopes on each segment, relative wave height meters and pressure gauges in the bow area. The beam was instrumented with strain gauges to measure the internal loads at the position of each of the cuts. Experiments have been carried out in regular waves at different amplitudes for the same wave period and in long crested irregular waves for a matrix of wave heights and periods. The results of the experiments are compared to results of calculations with a linear model based on potential flow theory that includes the effects of the flexural modes. Some of the tests were repeated with additional links between the segments to increase the model rigidity by several orders of magnitude, in order to compare the loads between a rigid and a flexible model.

• 동아시아식생활학회지
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• 제21권3호
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• pp.338-344
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• 2011

In this study, muffins were produced using dropwort powder and to the quality characteristics such as volume, height and moisture content The results showed that the height of the muffin was 5 cm and there were no significant differences across samples (p<0.05). The volume of the muffin increased as the amount of dropwort powder increased. With respect to the moisture content, a comparison group showed a moisture content of 26%, and the 3%-added and the 6%-added groups did not show any significant difference. The 9%-added group, however, did show a significant difference (p<0.05). The results of texture measurements showed that hardness increased as the amount of added dropwort powder increased. There were also significant differences in adhesiveness and springing across samples (p<0.05). With respect to cohesiveness, gumminess and chewiness, these characteristics tended to increase as the amount of added dropwort powder increased, and there were significant differences across samples (p<0.05). Sensory test results of added showed that the 3%-added group scored the highest for color, flavor and taste. For texture, the 6%-added group showed a value of 6.2, which was the highest texture. In terms of the overall acceptability, the 3% dropwort powder group showed a score of 7.2, which was the highest acceptability. These results suggest that the 3%-added group was the most desirable and appropriate.

• 동아시아식생활학회지
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• 제19권4호
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• pp.635-640
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• 2009

In this study, muffins were made with the addition of 0%, 3%, 6% and 9% of Chungkukjang powder and, the quality characteristics, such as volume, height, appearance, chromaticity and moisture contents, were measured using SEM (Scanning Electronic Microscope) measurement, texture tests and sensory tests. In the regards to volume, as the added amount of added Chungkukjang increased, the volume also increased. There was no significant difference in the height and moisture content of the muffins at the different Chungkukjang powder concentrations. Using SEM, it was shown that as the amount of added Chungkukjang increased, the gluten content decreased, which in turn caused the formation of thick cell membranes and rough pores and reduced gluten composition capacity. Luminosity L value in Chungkukjang muffin decreased as the amount of added Chungkukjang powder increased. There was significant difference in the red chromaticity a value and yellow chromaticity b value among the samples (p<0.05). The results of the texture test showed that the hardness of the Chungkukjang muffin decreased as the amount of added Chungkukjang increased. In addition, as the amount of added Chungkukjang increased, the adhesiveness decreased. There was no significant difference in springing, chewiness and gumminess among the samples. There was a significant difference in the cohesiveness among all other samples in cohesiveness (p<0.05). The results of the sensory test showed that the wave form of the Chungkukjang muffin decreased as the amount of added Chungkukjang increased. The pore of the muffin increased as the amount of added Chungkukjang increased. The color quality of the muffin decreased as the amount of added Chungkukjang increased. In terms of overall acceptability, 6% Chungkukjang was shown to result in the highest preference level.

• 대한조선학회논문집
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• 제50권4호
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• pp.217-223
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• 2013

This paper presents the wet damping estimation of the segmented hull model using the random decrement technique together with the continuous wavelet transform. The tested 16 sea states are grouped together based on the speed of the ship in order to figure out the possible influence of the ship speed on the damping ratio. The measured time histories of vertical bending moment for each tested sea state were processed with random decrement technique to derive the free decay signal, from which the damping ratios are estimated. Also, the autocorrelation functions of the filtered signal were calculated and comparison was made with the free decay signal obtained from the random decrement technique. Then the wet damping ratios for each sea state group, as well as precise wet natural frequencies, are estimated by using continuous wavelet transform. It turned out that the wet natural frequencies derived from the measured signal did not show any significant discrepancy compared with those obtained by wet hammering test, whereas the damping ratio did. It was considered that the discrepancy of the damping ratio between in calm and moving water may be attributed to the viscous effects caused by dramatically different flow pattern and relative velocity between the vibrating structure and surrounding fluid particles.

• 한국환경보건학회지
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• 제25권3호
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• pp.13-22
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• 1999

For the purpose of inquiring into the actual conditions of water quality management of Simple Piped Water Supply(SPWS) and the satisfaction and attitudes of inhabitants about utilizing water-supply, this research was done through the questionnaires, the investigation of surrounding environment and water quality analysis in the Sangju city, Kyungsang-pookdo during 4 months from March to June, 1998. The fountainhead of SPES using ground water accounted for 65.3%, which was the highest rate in the group. Most of them was at least 10 years in the number of utilization year. 79.6% of them were exposed to many sorts of surrounding pollution origins. The examination of water was performed only through a test about water purification and 24.5% of them disinfection by chlorine also no residual chlorine was detected at all. All the waterworks did not have any education to the managers of water quality and 81.5% of them held physical examination. As a result of the water examination about SPWS, 65.3% of them were found incongruity and the valley and springing water accounted for higher than the underground water in the rate of incongruity. Looking into the details of the result in the water examination, a category of colon bacilli was ranked in the highest rate and the next one was general bacilli, nitric acid nitrogen and turbidity in order. In the satisfaction degree of the water quality, the satisfied accounted for 44.6%, and 29.2% each. Over the state of satisfaction about the ways of water examination, satisfaction accounted for 44.6%, and unsatisfaction 28.3%. Summarizing the result of the above-stated, the state of Water Quality Management of the SPWS was in a poor condition. Thus for the water Quality Management, systematic and scientific water Quality Management mainly by the administrative organization other than voluntary management by the village should be done beyond doubt. Additionally the opinions and demands of inhabitants utilizing the water supply have to be positively reflected in the affairs of water Quality Management so that the distrust of inhabitants to the SPWS should be settled.

• 한국초등수학교육학회지
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• 제15권1호
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• pp.95-120
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• 2011

논술에서 요구되는 능력, 즉 논술 능력은 기본적으로 이해력, 논리적이고 창의적인 사고력, 표현력과 같은 고등사고능력이다. 그러나 이러한 논술 능력은 단기간에 신장되지 않는다. 더욱이 수학은 계열성이 강한 학문으로 이러한 능력의 신장을 위해서는 초등학교 저학년 때부터 차근차근 단계에 맞게 준비해야하는 것은 어찌 보면 당연한 일이다. 그러나 현재 초등 수리 논술에 대한 용어의 정의가 없어 사교육 시장을 중심으로 무분별하게 초등 수리 논술이라는 용어가 사용되고 있다. 초등학교는 1학년부터 6학년까지 다양한 발달단계의 학생들이 모여 있는 곳이다. 초등 논술이 입시논술과 그 성격과 지도방향이 다르듯 초등 수리 논술 또한 그 성격과 지도 방향이 달라야 한다. 논술 능력은 단기간에 완성되는 것이 아니므로 어릴 때부터 꾸준한 연습이 필요하며, 더욱 중요한 것은 흥미를 잃지 않도록 하는 것이다. 따라서 초등 수리 논술의 올바른 개념을 정립하고, 성격과 지도방향을 설정하여 후속연구를 활발히 해야 할 필요성이 있다.

• 한국산림과학회지
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• 제85권4호
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• pp.571-576
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• 1996

충청북도(忠淸北道) 단양군(丹陽郡) 영춘면(永春面) 상리(上里) 휴석동(休石洞) 땅밀림형 산사태지(山沙汰地)의 지질특성(地質特性) 및 수문상황(水文狀況)을 조사 분석한 결과, 연구대상지의 토질(土質)은 고결도(固結度)가 낮고, 투수성이 높은 혈암(頁岩), 사암(砂岩), 석회암(石灰岩) 등이 혼재한 사력층(砂礫層)으로 구성되고 대규모 돌너덜지대가 여러 곳에 분포하고 있었으며, 지표토양은 하부로 갈수록 토양(土壤) 용적밀도(容積密度)가 증가하고, 공극비(孔隙比)가 감소하는 경향을 보여 땅밀림형 산사태(山沙汰) 발생에 의한 지표토양(地表土壤)의 압축현상(壓軸現象)이 나타난 것으로 해석되었다. 또한, 지표(地表)에는 투수성이 높은 토양구조상(土壤構造上)의 특성(균열(龜裂) 및 함몰현상(陷沒現象) 발생 등)으로 인하여 강우수(降雨水)의 대부분이 지중(地中)으로 침투(浸透)하여 지표류거수량(地表流去水量)이 적고, 하단부 포락(浦落)벼랑에서 용출수(湧出水) 지점(地點)이 다수(多數) 확인되었다. 한편, 연구대상지에서는 산사태(山沙汰) 토괴(土塊)의 급속한 운동(運動)을 초래하는 70mm/day 이상의 강우강도를 가진 집중호우(集中豪雨)의 발생이 많음으로 인해, 이러한 집중호우가 산사태(山沙汰)를 발생시킨 주요 원인중 하나인 것으로 판단되었다. 이상의 결과를 종합해 볼 때, 휴석동 땅밀림형 산사태지(山沙汰地)는 지질(地質) 및 수문적(水文的) 상황(狀況)과 기상요인(氣象要因) 등의 여러 인자(因子)들이 상호 밀접하게 관련(關聯)되어 발생됨을 알 수 있었으며, 향후(向後) 이러한 관련인자(關聯因子)들에 대한 정밀한 조사(調査)와 연구(硏究)가 지속적으로 수행되어져야 할 것이다.