• Journal of Biosystems Engineering
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• v.41 no.1
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• pp.12-20
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• 2016

Purpose: Pepper prices have risen continuously because of a decrease in cultivation area; therefore, mechanical harvesting systems for peppers should be developed to reduce cost, time, and labor during harvest. In this study, a screw type picking head for a self-propelled pepper harvester was developed, and the optimal working conditions were evaluated considering helix types, winding directions of helix, and rotational speeds of the helix. Methods: The screw type was selected for the picking head after analyzing previous studies, and the device consisted of helices and a feed chain mechanism for conveying pepper branches. A double helix and a triple helix were manufactured, and rotational speeds of 200, 300, and 400 rpm were tested. The device was controlled by a variable speed (VS) motor and an inverter. Both the forward and reverse directions were tested for the winding and rotating directions of the helix. An experiment crop (cultivar: Longgreenmat) was cultivated in a plastic greenhouse. The test results were analyzed using the SAS program with ANOVA to examine the relationship between each factor and the performance of the picking head. Results: The results of the double and triple helix tests in the reverse direction showed gross harvest efficiency levels of 60-95%, mechanical damage rates of 8-20%, and net marketable portion rates of 50-80%. The dividing ratio was highest at a rotational speed of 400 rpm. Gross harvest efficiency was influenced by the types of helix and rotational speed. Net marketable portion was influenced by rotational speed but not influenced by the type of helix. Mechanical damage was not influenced by the type of helix or rotational speed. Conclusions: Best gross harvest efficiency was obtained at a rotational speed of 400 rpm; however, operating the device at that speed resulted in vibration, which should be reduced.

• BMB Reports
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• v.32 no.4
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• pp.405-408
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• 1999

The transactivation potential of HIV-1 Vpu was identified from the yeast two-hybrid screening process. The helix II domain of HIV-1 Vpu protein and mutant Vpu protein lacking the transmembrane domain exhibited transactivation of the LacZ and Leu2 reporter genes carrying LexA upstream activating sequences, but full-length HIV-1 Vpu and the helix I domain of HIV-1 Vpu did not. The helix II domain of HIV-1 Vpu consists of a number of acidic amino acids, and is especially rich in glutamic acid, a characteristic of many transcription factors. This result suggests that protein-protein interaction may occur through the acidic helix II domain of HIV-1 Vpu.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.4
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• pp.138-146
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• 1997

The optimal drill helix angle, point angle, and cutting conditions are recommended in the study so as to maximize the drilling performance by investigating the experimental reaults concerning with the state of chip formation, roundness of machined holes, and geometry of projected burr at hole exit, which are examined under the conditions of various helix angles, drill point angles of twist drill, cutting speeds, and feeds in operional parameters. In the easiness of chip escape, the helical type of chip is producted when a helix angle is 30$^{\circ}$, drill point angle 118$^{\circ}$, 140$^{\circ}$and feed is st between 0.1 and 0.15mm/rev. Roundness of machined hole is improved when the helix angle is 37$^{\circ}$, drill point angle is 118$^{\circ}$, and feed is 0.15mm/rev. The height of projected burr at the button of machined hole increases when the drill point angle and helix angle becomes large.

• Journal of the Korean Mathematical Society
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• v.54 no.4
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• pp.1331-1343
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• 2017

A curve ${\gamma}$ immersed in the three-dimensional sphere ${\mathbb{S}}^3$ is said to be a slant helix if there exists a Killing vector field V(s) with constant length along ${\gamma}$ and such that the angle between V and the principal normal is constant along ${\gamma}$. In this paper we characterize slant helices in ${\mathbb{S}}^3$ by means of a differential equation in the curvature ${\kappa}$ and the torsion ${\tau}$ of the curve. We define a helix surface in ${\mathbb{S}}^3$ and give a method to construct any helix surface. This method is based on the Kitagawa representation of flat surfaces in ${\mathbb{S}}^3$. Finally, we obtain a geometric approach to the problem of solving natural equations for slant helices in the three-dimensional sphere. We prove that the slant helices in ${\mathbb{S}}^3$ are exactly the geodesics of helix surfaces.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.947-950
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• 2000

The purpose of this paper is to investigate the effect of the helix angle of endmilling cutter on the cutting characteristics of inconel 718 in up endmilling. To this end cutters with helix angle of $20^\circ$, $30^\circ$, $40^\circ$ and $50^\circ$ degree have been prepared. And a modified cutting force model in up end milling process is presented. Using this cutting force components of 4-tooth endmills with various helix angles have been predicted. Predicted values of cutting force components are well coincide with the measured ones. As helix angle increases overlapping effects of the active cutting edges increase.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.45-50
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• 2007

In this paper, the FEM(Finite Element Method) has been applied to understand the geometrical characteristics and to analyze the stress of a helical gear. The helical gear is simulated and analyzed by adding many thin spur gear with helix angles and twist angles. Helical gears with different helix angle and face width have been studied. The results show that the root fillet stress is increased proportionally to helix angle and face width. Namely, as the face width increases, root fillet stress decreases, and as helix angle gets bigger, root fillet stress increases.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.5
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• pp.395-401
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• 2014

Development of five axis tool grinding machine and CAD/CAM systems increase tool design flexibility. In this research, investigated are cutting characteristics of ball-end mill with different helix angle. Special WC ball-end mills with $0^{\circ}$, $10^{\circ}$, $20^{\circ}$, $30^{\circ}$ helix angles are designed and used in various cutting tests. Machining performance according to helix angle variation is evaluated from cutting forces, surface roughness, tool wear, produced chip shape, and vibration characteristics. The ball-end mill with $10^{\circ}$ helix angle shows the best cutting performance due to appropriate chip load distribution and smooth chip flow. This research can be used for cutting edge geometry optimization and novel design of ball-end mill.

• Journal of Technology Innovation
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• v.31 no.2
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• pp.29-58
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• 2023

The knowledge and technological competitiveness produced by universities determines a country's scientific technology and industrial competitiveness. The aim of this study is to find the evolution of Triple Helix Model (THM) by analyzing cases of technological catching-up and nurturing the human capital policies during Korea industrialization era, from 1960 to 2020. To fulfill the aims, this study utilized qualitative methodologies. In this study not only the process of acquiring technologies and core technologies but also the system for nurturing the human capital focused on scientific and engineers was analyzed. In addition characteristics of each ear of Triple Helix Model (THM) were examined. From the results, this study suggests Triple Helix Syncro-Scenario (THSS) which is the compelling innovation model, based on scenario, combined the personal experiences various critical thoughts and problems with enterprises and government for creating the incessment innovations.

• Asian Journal of Innovation and Policy
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• v.6 no.3
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• pp.313-331
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• 2017

This paper exhibits the concept of Triple Helix model to explain and link university-industry-government (Triple Helix) connections to national innovation systems theory. The driver of this paper is to test the dynamics of Triple Helix concept under national innovation system in the Association of South East Asian Countries (ASEAN)-5 economies. Panel econometric analysis with cross-sectional dependence (CD) test is applied to investigate the relationship amongst Triple Helix variables. The empirical analysis employs innovation indicators of five founding ASEAN countries namely Malaysia, Indonesia, Singapore, the Philippines and Thailand for the period of 2000-2015 from an existing WDI and WCY database. Econometric results support the two research questions of this study; firstly, there is a significant relationship between innovation outcome and its key drivers under Triple Helix context of National Innovation System in ASEAN-5 economies; secondly, the extent of the relationship among government R&D expenditure with high-tech productions are positive and significant while new ideas coming from universities as scientific publications and high-tech production have positive relationship but not significant yet in ASEAN-5 countries. Overall labor productivity is positive and significant with innovation outcomes in ASEAN-5.

• Journal of Koreanology Reviews
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• v.2 no.1
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• pp.1-8
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• 2023

The South Korean automotive industry has been the major producer for both domestic and international market. This rises of the South Korean automotive industry has resulted in combination various factors ranging from government policies and the foreign investment. The Double Helix model provides a comprehensive and useful framework to understand how these factors have interacted to shape the history of the auto industry of South Korea. This research aims to provide the history of the Auto Industry in Korea based on the Double Helix Model. To collect textual literature dataset, the present author tried to screen and select adequate prior studies in the past and current literature to achieve the purpose of the study. According to the literature analysis, the history of the automotive industry in South Korea is an interesting case in the successful implementation of the Double Helix model. The model emphasizes the collaboration between the government and the private sector in achieving common goals. This research founded the four historical events of the development of the South Korean automotive industry based on the Double Helix Models. In sum, the research concludes that the Double Helix Model is an essential tool for understanding the historical development of the auto industry in South Korea.