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Determining Optimal WIP Level and Buffer Size Using Simulated Annealing in Semiconductor Production Line (반도체 생산라인에서 SA를 이용한 최적 WIP수준과 버퍼사이즈 결정)

  • Jeong, Jaehwan;Jang, Sein;Lee, Jonghwan
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.3
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    • pp.57-64
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    • 2021
  • The domestic semiconductor industry can produce various products that will satisfy customer needs by diversifying assembly parts and increasing compatibility between them. It is necessary to improve the production line as a method to reduce the work-in-process inventory (WIP) in the assembly line, the idle time of the worker, and the idle time of the process. The improvement of the production line is to balance the capabilities of each process as a whole, and to determine the timing of product input or the order of the work process so that the time required between each process is balanced. The purpose of this study is to find the optimal WIP and buffer size through SA (Simulated Annealing) that minimizes lead time while matching the number of two parts in a parallel assembly line with bottleneck process. The WIP level and buffer size obtained by the SA algorithm were applied to the CONWIP and DBR systems, which are the existing production systems, and the simulation was performed by applying them to the new hybrid production system. Here, the Hybrid method is a combination of CONWIP and DBR methods, and it is a production system created by setting new rules. As a result of the Simulation, the result values were derived based on three criteria: lead time, production volume, and work-in-process inventory. Finally, the effect of the hybrid production method was verified through comparative analysis of the result values.

A Study on the Types of Career Values of Science Core School Students and their Longitudinal Change (과학중점고등학교 학생들의 직업가치관 유형 탐색 및 종단변화)

  • Shin, Sein;Lee, Jun-Ki;Ha, Minsu
    • Journal of Science Education
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    • v.44 no.3
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    • pp.318-330
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    • 2020
  • This study has been conducted to identify the types and longitudinal changes in the career values of students in science core school. Data collected from 174 students in science core school were analyzed using 11 career value items. First, this study found that there are three types of career value shown in students in science core schools. Second, the career value of students in science core school did not differ by their track. Third, many students of science core high schools have little or no change in their career value values depending on the time of collecting data. However, some students show rapidly changing career values. These findings suggest the need for individualized career education based on the changing trend of students' career values.

Preventive Effects of Whole Grain Cereals on Sarcopenic Obesity in High-fat Diet-induced Obese Mice (고지방식이 동물모델에서 통곡물 시리얼의 근감소성 비만 예방 효과)

  • Kim, Mi-Bo;Lee, Sein;Kim, Changhee;Hwang, Jae-Kwan
    • Food Engineering Progress
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    • v.22 no.4
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    • pp.358-365
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    • 2018
  • Whole grain cereal (WGC)-rich diets provide macronutrients that are important for the regulation of energy metabolism. The current study evaluated whether WGCs had a preventive effect on sarcopenic obesity in high-fat diet (HFD)-induced obese mice. C57BL/6N mice were fed a normal diet (ND), ND+WGC, HFD, and HFD+WGC for 12 weeks. WGCs significantly reduced body weight gain, food efficiency ratio, fat mass, and adipocyte size in HFD-induced obese mice. WGCs attenuated HFD-induced nonalcoholic fatty liver disease by decreasing liver weight and hepatic fat accumulation. In addition, WGCs increased muscle strength and muscle mass in HFD-induced obese mice as well as in ND mice. Taken together, WGCs can be employed as functional food materials for the prevention of sarcopenic obesity by inhibiting fat accumulation and increasing muscle mass.

Vocational Rehabilitation of People with Mental Disabilities by Repeated Training of Horticultural Activities

  • Seol, Ga Ae;Yun, Suk Young;Choi, Byung Jin;Jang, Eun Jin;Jang, Hyun Hee
    • Journal of People, Plants, and Environment
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    • v.23 no.1
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    • pp.67-75
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    • 2020
  • The purpose of this study was to develop an effective horticultural activity program for the vocational rehabilitation of people with mental disabilities. The subjects of this study were seven persons with mental disabilities in the vocational rehabilitation team of a public health center located in G city, Gyeongsangbuk-do. A total of 10 horticultural programs were held from October 10 to December 11, 2018. Five programs were selected among those that were easy for the persons with mental illness to handle and their preference was high. In each session, the same task was repeated 10 times and finally changes in hand functions and working speed were measured. As a result, the assembly task of the Purdue Pegboard test was 23.6 (SD = 10.5) before the program, 26.6 (SD = 11.5) after planting, 27.7 (SD = 12.2) after wrapping pots, and 28.0 (SD = 13.9) after making mini flower baskets, 26.9 (SD = 12.0) after wrapping a single flower, and 29.1 (SD = 11.9) after making corsages. There was a significant difference between the five programs (p = .016). As a result of measuring the time taken to produce the same 10 products, the average planting time was 9.9 (SD = 4.0) minutes in the first class and 6.0 (SD = 2.3) minutes in the second class (p = .018), and making mini flower baskets was reduced from 35.2 (SD = 10.1) minutes to 21.0 (SD = 7.7) minutes (p = .018), wrapping a single flower from 23.3 (SD = 7.9) minutes to 16.2 (SD = 7.3) minutes (p = .043), and making corsages from 53.6 (SD = 15.9) to 40.8 (SD = 16.8) minutes (p = .043). The working time was significantly shortened in the second class compared to the first class. The class for wrapping pots was shortened from 52.7 (SD = 11.7) to 49.6 (SD = 17.8) minutes, but there was no significant difference (p = .398).

Threshold heterogeneous autoregressive modeling for realized volatility (임계 HAR 모형을 이용한 실현 변동성 분석)

  • Sein Moon;Minsu Park;Changryong Baek
    • The Korean Journal of Applied Statistics
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    • v.36 no.4
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    • pp.295-307
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    • 2023
  • The heterogeneous autoregressive (HAR) model is a simple linear model that is commonly used to explain long memory in the realized volatility. However, as realized volatility has more complicated features such as conditional heteroscedasticity, leverage effect, and volatility clustering, it is necessary to extend the simple HAR model. Therefore, to better incorporate the stylized facts, we propose a threshold HAR model with GARCH errors, namely the THAR-GARCH model. That is, the THAR-GARCH model is a nonlinear model whose coefficients vary according to a threshold value, and the conditional heteroscedasticity is explained through the GARCH errors. Model parameters are estimated using an iterative weighted least squares estimation method. Our simulation study supports the consistency of the iterative estimation method. In addition, we show that the proposed THAR-GARCH model has better forecasting power by applying to the realized volatility of major 21 stock indices around the world.

데데킨트 절단, 배중률, 관계

  • Hong, Seong-Gi
    • Korean Journal of Logic
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    • v.7 no.2
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    • pp.15-46
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    • 2004
  • Um die rationalen Zahlen auf die reellen Zahlen zu erweitern und dadurch die Stetigkeit der reellen Zahlen sicherzustellen, hat der deutsche Mathematiker R. Dedekind im Jahr 1872 in seinem Aufsatz "Stetigkeit und Irrationale Zahlen" einen neuen mathmatischen Begriff $eingef\ddot{u}hrt,\;n\ddot{a}mlich$ 'Schnitt'. Die Menge aller rationalen Zahlen Q wird durch eine rationale Zahl a zu zwei Untermengen $A_1=\{x|x{\leq}a,\;x{\in}Q\}$, $A_2=\{x|x>a,\;x{\in}Q\}$ $vollst\ddot{a}ndig$ geteilt. Wenn wir solche Teilung, d.i. solchen Schnitt mit "$(A_1,\;A_2)$" bezeichnen, ist ein $Identit\ddot{a}tssatz$ "a=$(A_1,\;A_2)$" absolut harmlos. Analog dazu glaubt Dedekind fest, $da{\beta}$ jede irrationale Zahl mit Hilfe von einem entsprechenden Schnitt $einzuf\ddot{u}hren$ ist. Zum Beispiel, falls die zwei Mengen $B_1=\{x|x^2<2,\;x{\in}Q\}$ und $B_2=\{x|x^2>2,\;x{\in}Q\}$ gegeben sind, dann $w\ddot{a}re$ die irrationale Zahl $^{\surd}2$ mit $(B_1,\;B_2)$ gleichzusetzen. Im Fall von einem Schnitt der Menge der rationalen Zahlen durch eine rationale Zahl, $(A_1,\;A_2)$, haben die beiden Untermengen $A_1$ und $A_2$ jwewils ein Supremum und ein Infimum und beide $m\ddot{u}ssen$ identisch sein, aber -wie schon Russell in seinem Buch "Introduction to Mathmatical Philosophy" dies kritisiert- hat ein Schnitt $f\ddot{u}r$ die $Einf\ddot{u}hrung$ der irrationalen Zahl, $(B_1,\;B_2)$ keine solche $gl\ddot{u}cklichen$ Eigenschaften. Dennoch glaubt Dedekind an eine streng wissenschaftliche Fundierung der irrationalen Zahl fest, und $w\ddot{u}rde$ nach dem Grund seines Glaubens befragt, $k\ddot{o}nnte$ er nur seine Behauptung wiederholen, ein klarer Fall circulus vitiosus. Mit anderen Worten, die $L\ddot{u}cke$ zwischen $B_1$ und $B_2$ durch die $Einf\ddot{u}hrung$ einer [einzigen] wissenschaftlich fundierten irrationalen Zahl $\ddot{u}berbr\ddot{u}ckt$ und das Ganze zu einem Kontinium gemacht werden sollte, bleibt dieses Vorhaben von Dedekind erst als eine Hoffnung und dessen Resultat kann $h\ddot{o}chstens$ nur als ein Postulat, aber keineswegs als ein methodisch einwandfreier Beweis betrachtet werden. Die Probleme, die mit dem Versuch der $Einf\ddot{u}hrung$ der irrationalen Zahlen mit Hilfe von Schnitt verbunden sind, sind nicht spezifisch allein im Gebient der Mathmatik, sondern betreffen immer wieder die Rechtfertigungsfrage der $Einf\ddot{u}hrung$ der letzten Bestandteile im bezug auf eine Systemerstellung, egal ob dies System ein Wissenschaftliches oder unsere $allt\ddot{a}gliche$ Sprachhandlung ist. $F\ddot{u}r$ all diese Rechtfertigungsfragen gilt das in der klassischen Logik $g\ddot{a}ngige$ logische Prinzip tertium non datur nicht mehr, aber nicht nur wegen der von praktischen $Unm\ddot{o}glichkeit$, die unendlichen vielen $Gegenst\ddot{a}nde$ durchforschen zu $m\ddot{u}ssen$, das $hei{\beta}t$, wegen der erkenntnistheoretischen $Beschr\ddot{a}nktheit$ des jetzigen Erkenntnisniveau, sondern auch wegen des speziellen ontologischen modus der $eizuf\ddot{u}hrenden$ Objekten. Der Autor des Aufsatzes analysiert $\ddot{a}nliche$ $F\ddot{a}lle$ (das Urmeterbeispiel und die Chrakterisierungen der geometrischen Axiome von Wittgenstein), und versucht mit Hilfe von beiden Begriffen, 'interne' und 'externe' Relation, zu zeigen, $da\beta$ eine gemeinsame, invariante Struktur in den eben genannten $F\ddot{a}llen$ besteht. Am Ende des Aufsatzes setzt der Autor sich mit der logischen Argumentationsstruktur des Zitates tiber 'Grenze' aus Noten von Leonardo da Vinci auseinander, und weist auf einen $m\ddot{o}glichen$ Zusammenhang der Grundidee seienes Aufsatzes mit der Philosophie der indischen Denker $N\bar{a}g\bar{a}rjuna$ hin, obwohl die zitierten Versen aus dem Hauptwerk von $N\bar{a}g\bar{a}rjuna$, dem Mittleren Weg$(Madhyamakak\bar{a}rik\bar{a})$ nur andeutend sein $m\ddot{o}gen$.

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An Analysis of the Policy-Knowledge-Power Dynamics in Higher Education Reform in Transitional Myanmar (전환기 미얀마 정치사회변화와 신(新)고등교육 개혁: 정책·지식·권력의 역동을 중심으로)

  • Hong, Moon-Suk
    • Korean Journal of Comparative Education
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    • v.28 no.3
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    • pp.135-159
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    • 2018
  • This thesis compares and analyzes the dynamics between policy, knowledge and power of Myanmar's higher education development. The papers begins by exploring the dynamics during the Socialist Military Regime(1962~1988), the Collapse of Higher Education Era(1988~2010), Thein Sein's Reform Era(2010~2015) and the current Aung San Suu Kyi's Civilian Era(2015~Now). By highlighting recent dramatic policy changes, the article argues that the policy discourse on the subject of internationalization of higher education and the technocratization of education development policy by the current Civilian Government in its new policy discourse, that resulted in the active participation as well as the contributions of international donors has directly impacted on the policy dynamics around the Comprehensive Education Sector Review and the introduction of the National Education Strategic Plan 2016~2020. Further, by examining complex interaction between the current domestic education stakeholders and international donors in education sector in Myanmar, this thesis argues that the new analytical framework on the understanding of policy dynamics in developing countries goes beyond the national level. The paper argues that there needs to be broadening of the analytical framework towards the multidimensional analysis perspective that includes global, national as well as local level policy, knowledge and power dynamics in Myanmar's dynamically changing higher education sector.

The Development and Validation of Instrument for Measuring High School Students' STEM Career Motivation (고등학생들을 위한 이공계 진로동기 검사도구 개발 및 타당화)

  • Shin, Sein;Ha, Minsu;Lee, Jun-Ki
    • Journal of The Korean Association For Science Education
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    • v.36 no.1
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    • pp.75-86
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    • 2016
  • The purpose of the present study is to develop and validate an instrument to assess STEM career motivation. We developed 32 items for 7 constructs (i.e. education experience, career value, academic self-efficacy, career self-efficacy, career interest, parents' support, and career motivation) on STEM career motivation based on Social Cognitive Career Theory (SCCT; Lent et al.,1994). 767 first year high school students participated in this study. The items were validated by Messick's framework (1995). In this study, we examined the validity of items in four aspects (i.e. content, substantive, structural and generalizability of validity). Methodologically, we used Rasch analysis, Exploratory factor analysis, confirmative factor analysis based on structural equation modelling. We confirmed that our instrument with 32 items as valid and reliable for measuring the STEM career motivation. In addition, we tested the STEM career motivation model based on SCCT. Our model explained the data well, suggesting that external factors (education experience and parents' support) and cognitive factors (perception of value, self-efficacy and interest) were significantly related to STEM career motivation.

The Development and Validation of Instrument for Measuring High School Students' Attitude Toward Convergence (고등학생들의 융합에 대한 태도 검사도구의 개발과 타당화)

  • Shin, Sein;Ha, Minsu;Lee, Jun-Ki;Park, HyunJu;Chung, Duk-Ho;Lim, Jae-Keun
    • Journal of The Korean Association For Science Education
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    • v.34 no.2
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    • pp.123-134
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    • 2014
  • This study aims to develop and validate an instrument to measure students' attitude toward convergence. To do so, we have defined five constructs (i.e. knowledge about convergence, personal relevance, social relevance, interest and self-efficacy) of 'attitude toward convergence' based on literature review, developed items, and collected data from 233 11th grade science track students. The validity of these items have been evaluated by Messick's framework (1995) (i.e. content, substantive, structural aspects of validity), experts' review, Rasch analysis, and confirmatory factor analysis using structural equation modeling. Our results have confirmed the five constructs and 23 selected items have met the benchmark of item validity. Moreover, the theoretical model illustrating that the high level of attitude toward convergence increases the level of science motivation has also been supported by the data. The items developed in this study will be used to measure students' attitude toward convergence and to estimate the effect of learning program for convergence science.

The Relationship of Engineering Education Accreditation Program, Gender, and Academic Year with Attitude towards Convergence among Engineering Students: Application of Latent Class Analysis (공과대학 학생들의 융합에 대한 태도와 공학교육인증, 성별, 학년과의 관련성 -잠재집단분석의 적용-)

  • Lee, Jun-Ki;Shin, Sein;Rachmatullah, Arif;Ha, Minsu
    • Journal of The Korean Association For Science Education
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    • v.37 no.1
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    • pp.113-123
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    • 2017
  • The purpose of this study is to investigate engineering students' attitude toward convergence and relevance with engineering education accreditation, gender, and academic year and attitude toward convergence. To be specific, fist, we examined whether the instrument for measuring attitudes toward convergence were reliable and valid for engineering students. Second, we compared levels of attitudes toward convergence in terms of engineering education accreditation, gender and academic year. Third, latent classes, which were distinguished in terms of attitudes toward convergence, were identified. Participants were 2076 engineering students. By using factor analysis and Rasch analysis, validity and reliability of instrument measuring attitudes toward convergence were confirmed. The differences in attitude toward convergence in terms of engineering education accreditation experience, gender, and academic year were examined by independent t-test and ANOVA. There were significant differences in attitude towards convergence in terms of engineering education accreditation, gender, and academic year. Students who experience engineering education accreditation program and male and high academic year have higher levels of attitude toward convergence than others. Lastly latent class analysis (LCA) was conducted to identify subgroups underlying engineering students in terms of attitude toward convergence and five latent classes were identified. In addition, the chi-square results showed that there were significant relationships between identified latent classes and engineering education accreditation, gender, and academic year. Based on these results, engineering education considering students' characteristics and diversity in attitude toward convergence were discussed.