• 한국전산구조공학회논문집
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• 제26권5호
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• pp.327-333
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• 2013

이 연구의 목적은 축소된 탱크 모델에서 측정되어진 슬로싱 압력을 이용하여 실제 크기의 탱크 모델에서의 압력을 예측하는 것이며, 또한 예측된 압력으로 LNG 코너 블럭의 슬로싱 하중에 의한 구조 강도를 평가하는 것이다. 이 목적을 위하여, Ansys CFX 프로그램을 이용하여 138K급 LNG 화물창 시스템의 크기 비율에 따른 슬로싱 해석을 수행 하였으며, 크기 비율에 따른 슬로싱 평균 압력 및 최대 피크 압력을 측정하였다. 또한, 측정된 압력은 프루드 법칙에 의해 실제 138K 크기의 압력으로 변환하여 실선 크기의 KC-1 코너블럭에 대한 구조강도 평가를 수행하였다.

• 공학교육연구
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• 제24권5호
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• pp.38-45
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• 2021

The CanSat was designed as an educational satellite simulation program that implements the overall system of the satellite such as the command processing unit, the communication unit, and the power unit in a structure of the size of a can. In particular, the training effect is very excellent because the trainee can learn a process similar to the actual satellite development process by designing, manufacturing, testing, and launching. Republic of Korea Air Force Academy has been using the CanSat production kit used by the domestic can satellite contest experience department for education, but since it was produced based on PCB, it was impossible to show creativity and operation was restricted even with small mistakes. In this paper, we analyze the existing CanSat kit and propose a new educational CanSat kit that can be used in creative engineering design and practice subjects that will be reorganized into a regular course from 2021, and a lesson plan. In conclusion, by using the proposed CanSat kit for lectures, it is possible to achieve educational purposes and effects, improve lecture satisfaction, and provide stable instruction.

• 품질경영학회지
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• 제50권2호
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• pp.287-304
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• 2022

Purpose: The size of the salad consumption market has expanded since Covid-19, and continuous growth is predicted. Therefore, by extracting influential core purchasers in the salad consumption market and analyzing their purchasing behaviors and consumer types, this study intended to provide basic data for establishing a marketing strategy. Methods: The analysis data is the purchasing data of 576 people who have purchased salads between 2016 and 2020 (panel data of the Rural Development Administration), and in the social network analysis, the centrality structure was analyzed. Results: First, in the results of analyzing the causes of the rapid increase in salad consumption in 2020, it was found that the increase in consumption of new purchasers (n=102) had little effect. The existing consumer type (n = 474), which has been the majority of the salad consumption market so far, were consumers with stable income. However, the results of study indicated that the type of consumers has expanded since low-income class as well as high-income class increased consumption of purchasing salad. Second, in the results of analyzing the types of key purchasers with great influence in the salad consumption market, there was a difference from the results of frequency analysis in age, number of family members, existence/absence of children, and income decile. This suggests that there should be a difference between the type of customers according to the apparent quantitative figure and the actual influential purchasers. Third, in the results of analyzing the salad purchasing behaviors of core purchasers, the purchasing site for existing purchasers was large-scale marts and for new purchasers it was corporate-type supermarkets. Purchases were concentrated on Saturdays for both existing and new purchasers. As for the purchased products, existing purchasers had a high preference for products made of chicken, and new purchasers had a high preference for vegetable/fruit salad. In particular, in the results of purchased products by age group, in the case of 50s and 60s, it was an interesting result that there was a difference between the products purchased by the existing and new purchasers even though they were the same age. Conclusion: When establishing a marketing strategy in the salad consumption market, it is necessary to pay attention to the purchasing behavior of key buyers.

• 한국건설안전학회 논문집
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• 제6권1호
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• pp.12-18
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• 2024

건축물의 초고층화, 대형화, 다양화가 가능하고 콘크리트 단면의 축소로 구조물 자중이 경감되어 보와 슬래브 두께를 얇게 함으로 층고를 증감하거나 같은 높이에서 많은 층수를 축조할 수 있고 넓은 유효공간이 확보되며, 기초 저면 지정에 사용된 자재 및 철근과 콘크리트 양을 절감하는 효과를 기할 수 있다. 현장시공 및 품질측면에서는 낮은 물결합재비 배합으로 건조수축 발생 저감 효과와 콘크리트 표면의 블리딩 최소화 효과를 얻을 수 있으며, 고성능감수제 사용에 의한 유동성 증진으로 자체 충전성이 확보되어 현장시공이 용이해지며, 콘크리트의 조기 강도 발현으로 거푸집 탈형 기간을 단축시킬 수 있는 장점이 있다. 특히 근래에 들어 콘크리트와 관련한 건축기술의 비약적인 발전에 따라 초고층 건축물에서는 설계기준강도 100MPa급 이상의 초고강도콘크리트의 적용이 확대되고 있다. 그러나 최근 국내에서도 120층 이상의 초고층 건축물들이 발주 또는 발주 예정되어 있으나, 현장 적용성이 고려된 130MPa급 이상의 초고강도 콘크리트를 개발하여 현장에서 실제 적용 가능성 여부를 실험, 평가한 연구실적은 미흡하다. 본 연구에서는 초고강도콘크리트의 현장적용 가능성을 확인하기 위하여 여러 가지 방법의 실내기초 실험으로 연구되어진 최적의 배합비를 찾아서 축소모의부재 예비실험을 실시하였다. 그 후 실물크기와 유사한 모의부재에 130MPa급 초고강도콘크리트를 레미콘 공장에서 생산하여 현장 펌프압송 타설을 통해 콘크리트의 유동특성, 강도특성, 수화열에 관하여 실험 연구하였다.

• 한국인구학
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• 제16권2호
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• pp.84-110
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• 1993

This study aims at identifying the recent change in marriage behaviors in Korea. The data used here is the vital statistics compiled from the vital registration system of which registration form is put on one from together with the civil registration form. According to the results of this analysis, since 1970 the number of marriages has steadily increased from about 300, 000 in the former of 1970s to about 400, 000 in the latter of 1980s, appproximately coincided with the change in population size at the marriageable age span. The few exceptions that can be seen in the 1970s seem to result from the impact of social upheavals during 1950s; since the birth cohorts affected by the low fertility during the Korean war and the post-war baby-boom generations chracterized by the high fertility entered the marriage market in the 1970s. However, the marriage rate shows a little increase from around 7 in the former of 1970s to around 9 in the latter of 1980s, indicating that the marriage prevalence has been more or less inconsiderably changed during this period. It is also found that the proportion of remarriage to the total marriages has increased to around 10 per cent in 1989, while decreasing that of first marriage. This fact can be attributable to the higher prevalence of divorces and the collapsing of the Confucianism ethic which contributed to expediting the remarriage of widows. Although this proportion is insignificant compared with that of the of more developed countries, it is not difficult to say that the proportion of remarriages will continue to increase in future. The age first at first marriage(AFM) which directly affects the span exposed to the risks pregnancy has increased to the age about 28 for male and about 25 for female in recent years. However, big difference in AFM between urban and rural areas has narrowed, resultant from the increasing involuntary postponement of marriage of rural young population who have met difficulties in seeking their bride or bridegroom in rural areas characterized by the heavy out-migration of young, particularly female, population. The present study shows the reverse relationship between AFM and educational attainment; i.e, the higher the educational attainment the lower the AFM. The conditions which are taken into considerations were the class and the family in the past time but which are, educational attainment, job and personal characteristics. With regard to the age condition, in recent years the male prefers the female younger than himself on the average by 3 years and vice versa, which is reduced form 4-5 years in beginning of 1970s. The age difference bride and bridegroom tends to decrease with the educational attainment increase. This may be attributable to the fact that the persons with the higher educational attainment prefer the love marriage and hence are more likely to choose their counterparts in the about same age. The education condition is characterized by the bridegroom having the higher educational level than bride. It is also significant to note that the proportion of love marriage has increased, whereas that of traditional arranged marriage has decreased. This is true in the urban areas than the rural areas, indicating that rights as well as responsibilities for marriage have been handed over the young population from their parents. In conclusion, the change in the marriage behaviors in Korea are characterized by increasing tendency for the postponement of first marriage, higher prevalences of divorces and a result remarriages, increase of love marriages, narrowing age difference between bride and bridegroom, etc. which are the main results of rapid industrization, increase in educational and economic activity opportunities and change in the ideals of marriages during the past decades. These phenomena prevailing in Korean society would affect not only the family structure that will become less proliferiated but the population size and structure. The most important is that the changes in marriage behaviors of Koreans and their impact on the society with respect to norms, values, morals, of individual and family in the social aspect, change in population size and structure in the demograpic aspects, and economic development in the economic aspects should be integrated into the plannings towards to the future.

• 수산해양기술연구
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• 제57권4호
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• pp.316-333
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• 2021

In order to understand basic data for improving the fishing system and fishing vessel structure in coastal improved stow net fishery, a questionnaire survey and on-site hearing were conducted from May 10 to June 11, 2019 to analyze opinions on the improvement of operation status and fishing vessel structure. The questionnaire survey consisted of ten questions on the operation status of coastal improved stow net fishery and six questions on the improvement of fishing vessel structure, and the results of each question were analyzed by the region, the captain's age, the captain's career and the age of fishing vessel. As a result of analyzing opinions on the operation status of the coastal improved stow net fishery, it was found that the average time required for casting net was 32.8 to 33.0 minutes and that the average time required for hauling net was 41.0 to 42.2 minutes which took 10 to 12 minutes more than for casting net. The most important work requiring improvement during fishing operation (the first priority) were 'hauling net operation,' 'readjustment and storage of fishing gear,' and 'fish handling' and the hardest factor in fishing management were in the order of 'reduction of catch,' 'labor shortage' and 'rising labor costs.' The most institutional improvement that is most needed in coastal improved stow net fishery was an 'using fine mesh nets.' Most of the respondent to the questions on the experience in hiring foreign crews was 'either hiring or willing to hire foreign crews,' and the average number of foreign crews employed was found to be 2.3 to 2.4 persons. The most important reason for hiring (or considering employment) foreign crews was 'high labor costs.' The degree of communication with foreign crews during fishing operation were 'moderate' or 'difficult to direct work.' The most important problem in hiring foreign crews (the first priority) was an 'illegal departure.' As the survey results on the opinion of structural improvement of coastal improved stow net fishing vessel, the degree of satisfaction with fishing vessel structure related to fishing operation was found to be somewhat unsatisfactory, with an average of 3.3 points on a five-point scale. The inconvenient structure of fishing vessel in possession (the first priority), the space needed most for the construction of new fishing vessel (the first priority) and the space considered important for the construction of new fishing vessel (the first prioprity) was a 'fish warehouse.' The most preferred equipment for the construction of new fishing vessel were 'engine operation monitoring' and 'navigation safety devices.' The average size (tonnage class), the average horse power and the average total length of fishing vessel for proper profit and safety fishing operation was between 13.8 and 14.0 tonnes, 808.3 to 819.5 H.P. and 23.4 to 23.5 meters, respectively. The results of the operation status of coastal improved stow net fishery and the requirement for improving the fishing vessel structure are expected to be provided as basic data for reference when we build or improve the fishing vessel.

• 생태와환경
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• 제52권4호
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• pp.285-292
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• 2019

본 연구에서는 영산강, 섬진강 유역에서 호소 간의 동물 플랑크톤의 군집구조 특성이 만수면적에 따라 분류된 소·중·대형의 저수지에서 종 수 및 개체수가 유의한 차이를 보이는 것을 확인하였다. 윤충류보다 지각류에서 민감도가 높은 것을 확인하였으며, 특히 두 분류군 모두 양의 상관 관계를 나타냈지만, 지각류에서 조사지점이 늘어날수록 개체수 증가가 확연한 것을 알 수 있었다. 또한 네트워크 분석 개념을 활용한 고유벡터 중심성 및 그룹화 분석을 사용하여 호소 간의 동물플랑크톤 군집구조를 비교했을 때, 만수면적에 따른 대·중·소형 호소 내에서도 지리적 특성과 미소환경 공간의 차이점을 구별할 수 있었다. 따라서 이러한 특성을 볼 때, 네트워크 분석은 담수 동물플랑크톤 군집구조 분석에 있어 만수면적 크기, 지리적 특성, 미소환경 특성을 반영할 수 있는 것으로 고려된다. 마지막으로, 네트워크 분석은 다양한 군집분석을 간소화하며 시각화를 통한 직관적 이해를 돕는 데 유용할 것이다.

• 한국학교보건학회지
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• 제12권1호
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• pp.97-107
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• 1999

The purpose of the study was to ascertain the trends of future circumstances in primary education along with population change. These trends, which are subject to change in population and structure, have a great impact on the size and characteristics of primary school-aged children. Accordingly, it is imperative for the government to plan for future conditions involving primary education. The major findings of the study were as follows: 1. In the long-term primary school children aged 6-11, which accounted for 17.7% of the total population in 1970, will decline to 8.6% by the year 2000, 6.9% in 2020 and 6.4% in 2030. This drastic reduction in fertility rate is a direct result of pressure by the government to control population. 2. In 1996, the total number of classes in primary schools rose to 106,594. In the future, these numbers will actually decline. By 2003 the total number of classes will peak at 142,605, but until then drop off to 112,288 by 2030-a decrease of over 6,000. 3. The actual number of primary schools in 1997 totaled 5,721. This figure will reach its highest peak, 5,942, in 2003, but it is expected decrease later after declining by 1,263, it will bottom out at 4,679 in 2003. 4. The number of teachers at primary schools increased from 101,095 in 1970, 119, 064 in 1980, 136,800 in 1990 to 138,369 in 1995. Accordingly this means that the ratio of students to teaching staff changed for the better. By the year 2005, if teachers of specialty subjects (music, art, English, physical education) are assigned to every primary school with over 18 classrooms and the number of students per class is 30, it should improve educational surroundings. This is because it is expected that the population of primary school children will continue to grow until 2003 and then decrease. Thus, there is a need to maintain the number of primary school teachers between the years 2003 and 2030 so that the ratio of students to teachers will be reduced to 1/20.25. In considering factors related to migration which influence conditions of education, it is evident that changes have already begun. In the suburbs of Seoul, population shifts are causing overcrowding in classrooms. The government believes it would be inefficient to invest in education because fluctuating migration figures make it impossible. Accordingly, we have to be concerned about stabilizing the population throughout the entire country.

• 한국항해항만학회지
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• 제30권6호
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• pp.439-446
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• 2006

선체는 기본적으로 판부재들의 조합으로 구성되어 있으며 상당수는 유공판(Perforated plate)으로 이루어져있다. 선체에 설치된 유공판으로서는 선체 상갑판 해치(하역시설로 사용), 선저부의 거더와 플로어(중량경감과 선박 건조 및 검사시 통로확보용), 다이어프램(중량경감 및 파이프 관통의 목적)등이 있다. 이들 유공판에 압축하중이 작용하면 좌굴과 극한강도 특성이 크게 변화할 뿐만 아니라 수반되는 면내응력도재 분포하게 되어 심각한 문제를 발생한다. 실적선에서는 유공주위에 스티프너 보강을 통하여 취약한 좌굴강도 보완하고 있으며, 유공을 고려한 실선에서 사용 중인 유공보강판 모델을 적용하여 좌굴강도 및 극한강도를 파악할 필요성이 있다. 이와 같은 측면에서 각 조선소에서는 각국 선급들이 제시하는 유공판의 좌굴설계식을 사용하여 강도계산을 하고 있으나 임의의 유공크기에 대한 좌굴강도 및 극한강도 평가법을 찾기란 매우 어려운 일이다. 본 연구에서는 실선에서 사용 중인 유공보강판의 모델을 조사하여 비선형 유한요소법(ANSYS)을 사용하여 면내 압축하중이 작용하는 경우에 대해서 유공비, 웹 치수, 두께 그리고 보강재 단면을 변화시켜가며, 극한강도 시리즈 해석을 수행하고 압축극한강도에 미치는 영향을 검토하였다.

• 한국안광학회지
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• 제20권2호
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• pp.237-246
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• 2015

목적: 본 연구는 안구에 존재하는 항산화효소인 superoxide dismutase(SOD)와 catalase(CAT)가 UV-B에 반복적으로 노출되었을 때 유발되는 구조변성 및 활성저하의 상관관계를 밝히며, 자외선 차단 RGP렌즈의 사용으로 효소의 변성과 활성저하가 효율적으로 차단되는가를 알아보기 위하여 수행되었다. 방법: SOD와 CAT의 표준품으로 각각의 효소용액을 제조하고 하루 30분, 1시간 및 2시간씩 312 nm의 UV-B에 1, 2, 3, 4 및 5일 동안 반복적으로 노출시켰다. 이 때 UV-B에 직접 노출시킨 항산화효소의 구조 및 활성변화를 자외선 차단기능이 있는 RGP렌즈로 UV-B를 차단시킨 경우와 비교하였다. UV-B 반복노출에 따른 SOD와 CAT의 구조변성은 전기영동분석으로 확인하였으며, 이들 효소활성은 분석키트를 이용하여 비색분석법으로 측정하였다. 결과: UV-B에 반복노출된 SOD는 일일 30분 조사조건으로 반복노출되었을 때에도 전기영동분석에서 효소다중화(polymerization)가 관찰되었으나 활성의 변화는 10% 이내로 나타났다. 반면 UV-B에 반복노출된 CAT은 전기영동 시 효소밴드크기나 진하기가 감소하여 구조변성이 나타났음을 확인할 수 있었으며, 반복노출시간이 긴 경우 CAT은 전기영동분석에서 효소밴드를 보임에도 불구하고 그 활성은 완전히 소실되었다. 또한 UV-B 조사로 인한 CAT의 변성은 63.7%의 UV-B 차단기능을 가진 RGP렌즈의 사용으로 어느 정도 억제되었으나 완전히 억제되는 것은 아니었다. 결론: 이상의 결과로 UV-B 반복노출에 따른 항산화효소의 구조변성은 그 종류에 따라 효소활성의 감소정도와 반드시 일치하는 것은 아님을 알 수 있었다. 따라서 자외선으로 인한 항산화효소의 손상을 막기 위하여서는 콘택트렌즈를 착용한 상태에서 자외선 노출시간을 최소화하거나, FDA Class I 차단제에 해당하는 UV 차단율을 가지는 콘택트렌즈를 착용 또는 이에 상응하는 UV차단율을 가지는 선글라스를 덧착용할 것을 권장한다.