• Title/Summary/Keyword: problem analysis

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A Study on the VADAMA improvements of latency performance through control message collision avoid in MF-TDMA satellite network

  • Su-Hoon Lee
    • Journal of the Korea Society of Computer and Information
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    • v.29 no.9
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    • pp.115-123
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    • 2024
  • This paper proposes a method to reduce the delay time caused by control message conflicts in VADAMA (Virtual Allocation Demand Assigned Multiple Access) technology, which is a virtual allocation based on-demand multiple access technology in MF-TDMA (Multi-Frequency Time Division Multiple Access) satellite network. Traditionally, satellite networks have had the problem that all network transmissions have long delay times due to control messages. In this study, in order to improve the delay time caused by terminal control message conflicts in VADAMA technology, the concept of virtual allocation is used to reduce the delay time. VADAMA-PTR (VADAMA Periodic Transmission) divides all terminals into subnets and transmits control. The method is proposed, and the performance analysis of the existing DAMA technology, delay time and data processing rate is performed using Matlab. The results show that the performance is improved.

A new surrogate method for the neutron kinetics calculation of nuclear reactor core transients

  • Xiaoqi Li;Youqi Zheng;Xianan Du;Bowen Xiao
    • Nuclear Engineering and Technology
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    • v.56 no.9
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    • pp.3571-3584
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    • 2024
  • Reactor core transient calculation is very important for the reactor safety analysis, in which the kernel is neutron kinetics calculation by simulating the variation of neutron density or thermal power over time. Compared with the point kinetics method, the time-space neutron kinetics calculation can provide accurate variation of neutron density in both space and time domain. But it consumes a lot of resources. It is necessary to develop a surrogate model that can quickly obtain the temporal and spatial variation information of neutron density or power with acceptable calculation accuracy. This paper uses the time-varying characteristics of power to construct a time function, parameterizes the time-varying characteristics which contains the information about the spatial change of power. Thereby, the amount of targets to predict in the space domain is compressed. A surrogate method using the machine learning is proposed in this paper. In the construction of a neural network, the input is processed by a convolutional layer, followed by a fully connected layer or a deconvolution layer. For the problem of time sequence disturbance, a structure combining convolutional neural network and recurrent neural network is used. It is verified in the tests of a series of 1D, 2D and 3D reactor models. The predicted values obtained using the constructed neural network models in these tests are in good agreement with the reference values, showing the powerful potential of the surrogate models.

IoT-based Smart alarm system (IoT 기반의 스마트 알람 시스템)

  • Ilyosbek Rakhimjon-Ugli Numonov;Tae-Kook Kim
    • Journal of Internet of Things and Convergence
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    • v.10 no.4
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    • pp.35-41
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    • 2024
  • Due to increasingly busy lifestyles, sleep time is gradually being reduced, leading to a growing interest in effective sleep methods. Traditional alarms that only ring at a set time can disrupt efficient sleep and increase fatigue. To solve this problem, a smart alarm system utilizing Raspberry Pi has been proposed. The proposed alarm not only rings at a preset time, like conventional alarms, but also helps by using an infrared sensor attached to the Raspberry Pi to detect the user's sleep onset time and calculate the optimal sleep duration, setting the alarm accordingly. Additionally, it allows for easy naps during the day by setting a fixed nap time. This Smart Alarm system was implemented using MIT App Inventor. The proposed Smart Alarm system is expected to contribute to more efficient sleep.

A Study on the Possibility of Utilizing Virtual Reality Technology for Successor Training of Intangible Heritage (무형유산의 전수교육을 위한 가상현실 기술의 활용 가능성에 관한 연구)

  • Hwa-Su Jin;Eun-Jee Song
    • Journal of Practical Engineering Education
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    • v.16 no.5_spc
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    • pp.689-700
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    • 2024
  • This study explored the possibility of utilizing virtual reality technology in successor training for the preservation of intangible heritage. In the midst of the crisis of transmission discontinuation due to the aging of holders, successor training of traditional skills in particular is becoming more difficult. As a solution to this problem, we propose the utilization of virtual reality technology. To this end, we conducted a survey on citizens' awareness and experience of utilizing virtual reality technology for intangible heritage and conducted in-depth interviews with holders and trainees at successor training sites. As a result of the analysis, it was evaluated that virtual reality technology would be effective in conveying historical meaning, establishing systematic learning, and archiving successor training courses and works in successor training of intangible heritage. In particular, repeated learning of traditional skills, reduction of risk factors, creative reinterpretation, and increased educational efficiency are expected through virtual reality. This study can be used as basic data for educational, academic, and industrial discussions on the preservation and utilization of intangible heritage in the future.

Corporate Default Prediction Model Using Deep Learning Time Series Algorithm, RNN and LSTM (딥러닝 시계열 알고리즘 적용한 기업부도예측모형 유용성 검증)

  • Cha, Sungjae;Kang, Jungseok
    • Journal of Intelligence and Information Systems
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    • v.24 no.4
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    • pp.1-32
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    • 2018
  • In addition to stakeholders including managers, employees, creditors, and investors of bankrupt companies, corporate defaults have a ripple effect on the local and national economy. Before the Asian financial crisis, the Korean government only analyzed SMEs and tried to improve the forecasting power of a default prediction model, rather than developing various corporate default models. As a result, even large corporations called 'chaebol enterprises' become bankrupt. Even after that, the analysis of past corporate defaults has been focused on specific variables, and when the government restructured immediately after the global financial crisis, they only focused on certain main variables such as 'debt ratio'. A multifaceted study of corporate default prediction models is essential to ensure diverse interests, to avoid situations like the 'Lehman Brothers Case' of the global financial crisis, to avoid total collapse in a single moment. The key variables used in corporate defaults vary over time. This is confirmed by Beaver (1967, 1968) and Altman's (1968) analysis that Deakins'(1972) study shows that the major factors affecting corporate failure have changed. In Grice's (2001) study, the importance of predictive variables was also found through Zmijewski's (1984) and Ohlson's (1980) models. However, the studies that have been carried out in the past use static models. Most of them do not consider the changes that occur in the course of time. Therefore, in order to construct consistent prediction models, it is necessary to compensate the time-dependent bias by means of a time series analysis algorithm reflecting dynamic change. Based on the global financial crisis, which has had a significant impact on Korea, this study is conducted using 10 years of annual corporate data from 2000 to 2009. Data are divided into training data, validation data, and test data respectively, and are divided into 7, 2, and 1 years respectively. In order to construct a consistent bankruptcy model in the flow of time change, we first train a time series deep learning algorithm model using the data before the financial crisis (2000~2006). The parameter tuning of the existing model and the deep learning time series algorithm is conducted with validation data including the financial crisis period (2007~2008). As a result, we construct a model that shows similar pattern to the results of the learning data and shows excellent prediction power. After that, each bankruptcy prediction model is restructured by integrating the learning data and validation data again (2000 ~ 2008), applying the optimal parameters as in the previous validation. Finally, each corporate default prediction model is evaluated and compared using test data (2009) based on the trained models over nine years. Then, the usefulness of the corporate default prediction model based on the deep learning time series algorithm is proved. In addition, by adding the Lasso regression analysis to the existing methods (multiple discriminant analysis, logit model) which select the variables, it is proved that the deep learning time series algorithm model based on the three bundles of variables is useful for robust corporate default prediction. The definition of bankruptcy used is the same as that of Lee (2015). Independent variables include financial information such as financial ratios used in previous studies. Multivariate discriminant analysis, logit model, and Lasso regression model are used to select the optimal variable group. The influence of the Multivariate discriminant analysis model proposed by Altman (1968), the Logit model proposed by Ohlson (1980), the non-time series machine learning algorithms, and the deep learning time series algorithms are compared. In the case of corporate data, there are limitations of 'nonlinear variables', 'multi-collinearity' of variables, and 'lack of data'. While the logit model is nonlinear, the Lasso regression model solves the multi-collinearity problem, and the deep learning time series algorithm using the variable data generation method complements the lack of data. Big Data Technology, a leading technology in the future, is moving from simple human analysis, to automated AI analysis, and finally towards future intertwined AI applications. Although the study of the corporate default prediction model using the time series algorithm is still in its early stages, deep learning algorithm is much faster than regression analysis at corporate default prediction modeling. Also, it is more effective on prediction power. Through the Fourth Industrial Revolution, the current government and other overseas governments are working hard to integrate the system in everyday life of their nation and society. Yet the field of deep learning time series research for the financial industry is still insufficient. This is an initial study on deep learning time series algorithm analysis of corporate defaults. Therefore it is hoped that it will be used as a comparative analysis data for non-specialists who start a study combining financial data and deep learning time series algorithm.

A Study on the Market Structure Analysis for Durable Goods Using Consideration Set:An Exploratory Approach for Automotive Market (고려상표군을 이용한 내구재 시장구조 분석에 관한 연구: 자동차 시장에 대한 탐색적 분석방법)

  • Lee, Seokoo
    • Asia Marketing Journal
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    • v.14 no.2
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    • pp.157-176
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    • 2012
  • Brand switching data frequently used in market structure analysis is adequate to analyze non- durable goods, because it can capture competition between specific two brands. But brand switching data sometimes can not be used to analyze goods like automobiles having long term duration because one of main assumptions that consumer preference toward brand attributes is not changed against time can be violated. Therefore a new type of data which can precisely capture competition among durable goods is needed. Another problem of using brand switching data collected from actual purchase behavior is short of explanation why consumers consider different set of brands. Considering above problems, main purpose of this study is to analyze market structure for durable goods with consideration set. The author uses exploratory approach and latent class clustering to identify market structure based on heterogeneous consideration set among consumers. Then the relationship between some factors and consideration set formation is analyzed. Some benefits and two demographic variables - age and income - are selected as factors based on consumer behavior theory. The author analyzed USA automotive market with top 11 brands using exploratory approach and latent class clustering. 2,500 respondents are randomly selected from the total sample and used for analysis. Six models concerning market structure are established to test. Model 1 means non-structured market and model 6 means market structure composed of six sub-markets. It is exploratory approach because any hypothetical market structure is not defined. The result showed that model 1 is insufficient to fit data. It implies that USA automotive market is a structured market. Model 3 with three market structures is significant and identified as the optimal market structure in USA automotive market. Three sub markets are named as USA brands, Asian Brands, and European Brands. And it implies that country of origin effect may exist in USA automotive market. Comparison between modal classification by derived market structures and probabilistic classification by research model was conducted to test how model 3 can correctly classify respondents. The model classify 97% of respondents exactly. The result of this study is different from those of previous research. Previous research used confirmatory approach. Car type and price were chosen as criteria for market structuring and car type-price structure was revealed as the optimal structure for USA automotive market. But this research used exploratory approach without hypothetical market structures. It is not concluded yet which approach is superior. For confirmatory approach, hypothetical market structures should be established exhaustively, because the optimal market structure is selected among hypothetical structures. On the other hand, exploratory approach has a potential problem that validity for derived optimal market structure is somewhat difficult to verify. There also exist market boundary difference between this research and previous research. While previous research analyzed seven car brands, this research analyzed eleven car brands. Both researches seemed to represent entire car market, because cumulative market shares for analyzed brands exceeds 50%. But market boundary difference might affect the different results. Though both researches showed different results, it is obvious that country of origin effect among brands should be considered as important criteria to analyze USA automotive market structure. This research tried to explain heterogeneity of consideration sets among consumers using benefits and two demographic factors, sex and income. Benefit works as a key variable for consumer decision process, and also works as an important criterion in market segmentation. Three factors - trust/safety, image/fun to drive, and economy - are identified among nine benefit related measure. Then the relationship between market structures and independent variables is analyzed using multinomial regression. Independent variables are three benefit factors and two demographic factors. The result showed that all independent variables can be used to explain why there exist different market structures in USA automotive market. For example, a male consumer who perceives all benefits important and has lower income tends to consider domestic brands more than European brands. And the result also showed benefits, sex, and income have an effect to consideration set formation. Though it is generally perceived that a consumer who has higher income is likely to purchase a high priced car, it is notable that American consumers perceived benefits of domestic brands much positive regardless of income. Male consumers especially showed higher loyalty for domestic brands. Managerial implications of this research are as follow. Though implication may be confined to the USA automotive market, the effect of sex on automotive buying behavior should be analyzed. The automotive market is traditionally conceived as male consumers oriented market. But the proportion of female consumers has grown over the years in the automotive market. It is natural outcome that Volvo and Hyundai motors recently developed new cars which are targeted for women market. Secondly, the model used in this research can be applied easier than that of previous researches. Exploratory approach has many advantages except difficulty to apply for practice, because it tends to accompany with complicated model and to require various types of data. The data needed for the model in this research are a few items such as purchased brands, consideration set, some benefits, and some demographic factors and easy to collect from consumers.

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The Influence of High School Students' Entrance Exam Stress on Their Mental Health (대입 준비생의 입시스트레스가 정신건강에 미치는 영향)

  • Lee, Hee-Ja;Park, Yung-Soo
    • The Journal of Korean Society for School & Community Health Education
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    • v.8 no.1
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    • pp.43-54
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    • 2007
  • This study aimed at investigating the level of high school students' entrance exam stress and mental health first and also investigating if the entrance exam stress and mental health are related to gender, grade, character type, parenting style and economic status. This is expected to be used as a fundamental data for the development of health education program on high school students' stress and diagnosis of their mental health. To achieve those goals above, the questionnaire was used and the sample consisted of 600 students from general high schools in a large city, C and in a smaller city, A in Chungnam province through questionnaire and the conclusion, which was based on 582 proper questionnaires from the 600 questionnaires, through variable analysis, correlation analysis and multi-regression, is below. First, according to the information provided by respondents, the result showed the relationship between those background variables and the entrance exam stress and mental health level. As the students are more introverted and the parenting style is more authoritative, the entrance exam stress is higher and the mental health level is higher as the parenting style is more authoritative and the economic status is lower. In gender, the entrance exam stress level was high for male students in regard to parents pressure. For female students, it was due to the insufficient free time. In test performance, the good grade group showed high stress level when they don't have enough free time and the poor grade group showed high stress level when they have test tension and poor test performance. In character style, the introverted group showed high stress level in future uncertainty. In parenting style, the authoritative group showed significantly high level in all four sub-factors and there is no significant relationship with the stress level and economic statue. Female students reported higher mental health level than male students in somatization and depression. In academic achievement, the poor grade group showed high level in obsession, fear-anxiety and psychotism. In character style, the introverted group showed high level in sensitivity towards others and depression. And in parenting style, the authoritative group is higher in 9 sub-factors than the other two groups in the factor, economic status. The lower economic status group showed high mental health problem level in this order; in obsession, sensitivity towards others, depression, paranonia and psychotism. Second, the results revealed that there is a significant difference among the groups after comparing and analyzing the relationship between the mental health level according to the three groups, the first, second and third group divided by the degree of entrance exam stress. And the higher the entrance exam stress is, the higher the mental health problem level is. Verification showed that there was obvious difference among the groups. the entrance exam stress was positively correlated with the mental health level. The lack of free time, future uncertainty, test anxiety/poor test performance and parents pressure, these factors, in that order, were correlated with the mental health level. when the prediction variables which influenced on mental health are analyzed, test-anxiety/poor test performance was found to be related to mental health most. And after the factor, test-anxiety, future uncertainty and the lack of free time were listed(ranked), however results did not show any correlation with parents' pressure.

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The Reduction ways of Medicine Material Costs of Nuclear Medicine In Vitro (핵의학 체외검사의 진료재료비용 절감 방안)

  • Song, Hun-Kang;Seo, Jung-Mi;Yang, Joon-Ho;Kim, Eun-Jung;Kim, Chang-Ho
    • The Korean Journal of Nuclear Medicine Technology
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    • v.15 no.2
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    • pp.111-115
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    • 2011
  • Purpose: In vitro uses dose response curve with 6 to 7 standard concentrations in every examination to analyze examination results and this use of dose response curve comprises a large portion of the consumption of medicine material. At this present, some ones of in-hospital examination items have shown mostly low result of distribution in the analyzed features and these examinations have been judged that it would be unnecessary to use the last standard concentration. Hence, this study selects those examination items showing low result of distribution and reviews the cases contributed to less consumption of medicine material and revenue growth of hospital by reduction of medicine material used in the place of the last standard concentration. Materials and Methods: The study was made targeting 11 examination items out of total 43 items of the in-hospital examination and since these examination items were mostly low in the features as the examination results of patients or the examination results were distributed to show lower concentration than the previous last standard concentration, it carried out the examination without using the last standard concentration, which could generate the effect to reduce medicine material (examination tube) used in the last standard concentration as many as the number of examination carried out. For this, it examined the number of medicine material reduction by month during the period from July, 2009 to February, 2011 and estimated the reduction amount of medicine material calculated the number of reduction by the unit cost of medicine material as well as the profit generated by the reduced medicine material to use for the medicine material of patient examination. Results: The total number of medicine material reduced during the period from July, 2009 to February, 2011 was 3,131 pieces, which had the effect to reduce the medicine material equivalent to about 31 kits of reagent. To calculate this by the unit cost of the medicine material, it analyzed to reduce about 6.4 million won of medicine material cost. Also the reduced medicine materials were used for medicine materials of patient examination and this was analyzed to generate about 13.75 million won of profit based on the ABC cost accounting. Conclusion: It showed no problem in the analysis of examination result even without using the last standard concentration regarding those examination items with low distribution of the patient examination result. For these examination items, it was able to reduce medicine material used for the last standard as many as the number of examination carried out. Also, the adjustment of concentration range was found to have no problem in the reliability of examination result. Therefore, this case will be applicable in those occasions of when the analysis of patient examination result is mostly distributed at the lower level or when an examination with the distribution of patient results in the range of lower concentration than the previous last standard concentration is carried out and this is considered to increase the efficiency in the use of medicine material in vitro as well as contribute to the profit of hospitals.

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A study on physical examination of middle school students (중학교 체질검사 실태에 관한 연구)

  • Park, Sung-Hee
    • Journal of the Korean Society of School Health
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    • v.14 no.1
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    • pp.131-143
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    • 2001
  • The primary aim of this dissertation is to contribute to the improvement of methods in physical examination by providing quality information for the current school system and advice for improving status. Present status, controversial points and possible remedies in physical examination were analyzed on a frequency and percentage basis. An $x^2$-test was used to verify the statistics between the results from the examination and each variable. In case of multiple categories of variables, an $x^2$ cs was adopted. Chronological data as well as both total and sampling physical examination data verified the statistics using an $x^2$-test. This thesis is based both on the data from middle school health care specialists in Gyunggi Province and on the analysis of physical examinations reported from local schools to the municipal education agency from 1997 to 1999. The results of the study are as follows: First, according to the survey, only 29.0% of the total schools had their school doctors examine all the students while most of the educational institutions failed to implement the whole process of physical examination on the list. It also turned out that the more students the schools have, the lower the rate of implementation of physical examination by school doctors(p=0.014). Second, the average time a school doctor spends for checkup turned out to be approximately 1.7 minutes per student This means that the quality of the physical examination is not guaranteed in the process. Third, 47.7% of those surveryed say that a dental examination was performed, each taking 21.24 seconds on average. In addition, it shows that some 31.5% wanted to have a task force team for dental checkups at the local health center. Given the fact that dental caries among students is progressively on the rise, the dental health centers that are now set up in some elementary schools should be expanded to cover the whole educational institution in order to raise awareness of the importance of dental care. Fourth, 48.5% of those surveyed say that a comprehensive physical examination should be adopted to promote the health of high schoolers. Since it takes a lot of public funds to implement a comprehensive method, it is essential to make sure that in-depth studies should be based on the frequency and methods of physical examination. Fifth, regarding such diseases among 3rd year middle school students in 1999, statistics shows that there was a slight difference in the prevalence rate of color blindness, and allergic diseases for male students ; and color blindness, hearing disturbance and allergic disease for female students. For those items, however, it is too little to say that there is a significant difference and accordingly it is assumed to be a problem of the measuring process. Sixth, the result of analysis on the sample physical examination and the total physical examination of the year 1999 shows as follows: For male students in the 3rd year of middle school, a slight difference appeared to those students in 11 items including eye problems and eye disease, otitis media, tonsillar hypertrophy, spinal shape, respiratory urinary allergic disease and other abnormal diseases(p<0.05). Particularly, the prevalence rate between students with and without disease was shown to be two times more in the following: eye problems, otitis media, tonsill hypertrophy, allergic diseases, etc. For female students in the 3rd year, prevalence rate showed little difference in 14 items(p<0.05). For items including eye problem, otitis media, tonsill hypertrophy, allergic disease, etc. it was shown that the rate was two times more between students with and without diseases. Physical examinations under the current school system are not producing any fundamental results for the health of the students. Methods and results are not trustworthy. Accordingly, a drastic overhaul of the current practices is needed in frequency, methods and items on the list in order to promote the health of the students. Cost-benefit studies as well as political considerations to ensure the development of efficient methods for physical examination are urgently needed at this moment.

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A Study on Selection and Organization of Educational Contents of Invention.intellectual property in secondary Vocational Education (중등단계 직업교육에서의 발명.지식재산 교육 내용 선정 및 조직 연구)

  • Lee, Chan-Joo;Lee, Byung-Wook;Lee, Sang-Hyun
    • 대한공업교육학회지
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    • v.40 no.1
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    • pp.1-22
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    • 2015
  • The purpose of this study was to select and organize educational contents needed to achieve systematic education of Invention intellectual property in secondary vocational education and ultimately to provide basic data for development of national-level curriculum. For this, the study, based on literature research, selected and organized educational contents of Invention intellectual property and learning elements in secondary vocational education, which served as the first draft. Then, the study verified its validity through experts' meeting and prepared its final draft. The experts' meeting comprized three teachers engaged in education of Invention intellectual property, two researchers (including a professor) and one person in charge of intellectual property. This study had following findings. First, the first draft of selection and organization of educational contents of Invention intellectual property in secondary vocational education as per the literature research suggested nine subject and 39 educational contents. The result of validity analysis for the suggested first draft turned out to be generally valid at 4.4 on average. Opinions modified and added by the experts' meeting were 30 in total with 5 altered, 20 modified and 5 added. Second, the result of validity analysis of learning elements in educational contents by the subject turned out to be generally valid. Average validity by the subject was revealed as Basics of invention 4.4, General invention/patent 4.5, Invention & problem solving 4.3, General intellectual property 4.5, Invention & design 4.6, Particulars of patents 4.4, Patent drawings 4.5, Patent & own business 4.5. Third, the final draft of educational contents of Invention intellectual property in secondary vocational education selected and organized eight subjects and 40 educational contents. The finally-suggested subjects included Basics of invention, General invention/patent, Invention & problem solving, General intellectual property, Invention & design, Particulars of patents, Patent information, Patent & own business.