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A Study on HMD-AR based Industrial Training System for Live Machinery Operation
Lee, Beomhee,Choi, Jinyeong,Choi, Byunghoon,Lee, Jisung,Min, Byungjun,Cho, Juphil The Institute of Internet 2018 International Journal of Internet, Broadcasting an Vol.10 No.1
As technological development is progressing recently, various technologies are actively being studied in the course of the 4th industrial revolution. So, even in the educational field, virtual reality and augmented reality technology are used in educational environments, but specialized additional equipment is required and the price is very expensive. Also, since a plurality of equipment are required for a large number of people, it is urgent to study the technology that can be effectively applied to the industrial education field. So in this paper, we propose an industrial training system for HMD-AR, MPEG-DASH and SOAP based HTTP based Live Machinery Operation using Smartphone to solve the problems of existing system.
Jisung Yoo,Won‑Mi Choi,Seok Su Sohn,Byeong‑Joo Lee,Gi‑Yong Kim,Hyungjun Kim,Won‑Doo Choi,Yong‑Jun Oh,Sunghak Lee 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.2
For maintaining high-performance turbo-charger housings at higher exhaust-gas temperatures, e.g., 1050 °C, a high-Ni(20 wt%)-containing austenitic steel (ASTM HK40 steel) has been actively modified. As a promising method, the solidsolutionhardening obtained from the V or Cu addition was utilized in this study. Five austenitic cast steels were made byadding V or Cu in the modified HK40 steel (N16 steel; 4%-Ni replacement by 4.6%-Mn), and the high-temperature propertyimprovement was explained by detailed microstructural evolutions coupled with thermodynamically calculated phase diagrams. The V- or Cu-added steels showed improvements in high-temperature properties over the N16 steel because the additionof V or Cu raised both austenite matrix hardness and volume fraction of M7C3carbide. Considering that only 3.6–4.8vol% of M7C3was present in the five austenitic cast steels, the strengths were affected more by the matrix hardness. Whenthe V or Cu content was quite high, however, the ferrite or Cu-coring is formed, thereby leading to the serious deteriorationof high-temperature properties. The V- or Cu-added steels within proper contents are applicable well to automotive turbochargerhousings requiring or emphasizing high-temperature tensile properties.
A HYBRID RECONSTRUCTION METHOD IN PARALLEL MRI
Jisung LEE,Yoon mo JUNG,Jin Keun SEO 한국산업응용수학회 2010 한국산업응용수학회 학술대회 논문집 Vol.5 No.1
Last decade, parallel MRI (pMRI) has been made a great deal of attention in MRI due to its important benefit of accelerating image acquisitions by the use of multiple receiver coils and its supplementary spatial information in the image space. In pMRI, we skip phase-encoding lines in the k-space as many as possible during MRI acquisition in order to minimize time-consuming phase encoding step, and in image reconstruction step we compensate the skipped k-space data by the use of space-dependent properties of multiple receiver coils. The goal is to develop a robust and fast reconstruction method using smallest possible data of phase encoding lines, while eliminating aliasing which is a consequence of violating Nyquist criteria due to skipping the data.We develop a reconstruction method with a hybrid sampling which combines SMASH method to fill a part of vacancies in k-space and image processing technique to eliminate aliasing in the image space.
Concept of Cold Energy Storage for Superconducting Flywheel Energy Storage System
Jisung Lee,Sangkwon Jeong,Young Hee Han,Byung Jun Park IEEE 2011 IEEE transactions on applied superconductivity Vol.21 No.3
<P>A superconducting flywheel energy storage (SFES) system is an energy storage device with unprecedented small kinetic energy loss by utilizing diamagnetic levitation property of superconductor. The system, therefore, is expected to be one of the most promising candidates in the application of renewable energy field such as PV (photovoltaic) or wind energy development where the power generation is intermittent. An innovative concept to store cold thermal energy as well as kinetic energy in the SFES system is proposed in this paper to decrease required cooling energy during the energy storage period. We have found that the cooling energy can be considerably decreased by the suggested cooling concept. The methodology of cold thermal energy storage is introduced, and the experimental validation is carried out. A specially designed thermosiphon is adopted as a thermal bridge between the high temperature superconductor (HTS) bulks and the cold head of cryocooler, and the working fluid of the thermosiphon is utilized as the thermal energy storage material. Solid nitrogen is generated in the thermosiphon by surplus electricity, and then the mock up HTS bulks are successfully cooled around 64 K by the existence of solid nitrogen even though the implemented cryocooler is turned off.</P>
Jisung Yoo,Won‑Mi Choi,Byeong‑Joo Lee,Gi‑Yong Kim,Hyungjun Kim,Won‑Doo Choi,Yong‑Jun Oh,Sunghak Lee 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.10
In order to increase the exhaust-gas temperature of austenitic stainless cast steels used for turbo-charger-housings up to1050 °C, the more excellent high-temperature strength should be obtained because it works for keeping a sustainability ofthe housing shape. Three austenitic stainless cast steels were fabricated in this study by adding Nb into the Ni/Mn-replacedconventional ASTM HK40 steel, and their high-temperature strength was investigated in relation with the carbide formationand matrix strengthening. The 1-wt%-Nb-added steel showed the enhancement in high-temperature strength over thenon-Nb-added steel. This indicated that the Nb addition was effective on the strength improvement because it raised boththe fraction of thermally-stable hard MC-type carbides and the austenite-matrix hardness. However, the 1.5-wt%-Nb-addedsteel showed the lower high-temperature strength than the 1-wt%-Nb-added steel, although it contained the more MC carbides. The more MC carbides reduced the matrix hardness, enlarged the hardness difference between carbides and matrix,and deteriorated the high-temperature strength. Our results demonstrate that the strengthened matrix as well as populatedcarbides due to the Nb addition are desirable for further improving the high-temperature strength.
Lee, Yoon Jae,Kim, SeongAe,Lee, Jisung,Chung, Joong Geel,Jun, Young Joon Korean Society of Plastic and Reconstructive Surge 2020 Archives of Plastic Surgery Vol.47 No.2
Background Infrabrow blepharoplasty has become a common surgical method used to rejuvenate aged upper eyelids in Asians. In this paper, we describe the parallel excision method for infrabrow blepharoplasty as a useful alternative to the conventional elliptical excision method. The authors' experience over a 3-year period is presented and reviewed. Methods A retrospective review of parallel excision infrabrow blepharoplasty cases at our hospital between 2014 and 2017 was performed. Three oculoplastic surgeons compared preoperative and postoperative photographs using the Strasser grading system. Results From the medical records of 123 patients, a total of 93 patients with moderate-to-severe bilateral dermatochalasis were selected as subjects. The exclusion criterion was levator function less than 8 mm. The total mean follow-up period was 2 years (range, 0.5-3.5 years). The mean skin excision height and width were 9.75 mm (range, 5-16 mm) and 58.51 mm (range, 42-75 mm), respectively. All patients who underwent surgery recovered without major complications, and all patients had high levels of satisfaction and improvements in their visual field. In the Strasser evaluation performed by the oculoplastic surgeons, most patients were found to have excellent results. Conclusions The parallel excision method for infrabrow blepharoplasty is a safe and effective technique that yields more natural- and youthful-looking eyelids than the conventional elliptical excision method. In our method, more effective manipulation of the orbicularis oculi muscle led to a reduction in frontalis compensation, resolution of sunken eyelids, and correction of lateral hooding.
Jisung Lee,Sungkyun Park 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.5
X-ray reflectometry was used to determine the chemical structure of oxidized Permalloy films grown at different oxidation times. The oxidation time-dependent thickness, roughness and chemical density of each layer were examined simultaneously using the Parratt formalism. With increasing oxidation time, the Permalloy thickness decreased while forming a new oxide layer. After oxidation for 40 sec, the Permalloy film’s thickness remained the same for further oxidation, indicating the formation of an oxidation barrier with a scattering length density much lower than that of the Permalloy. The interfacial roughness between the interface layer and the top protective layer remained the same regardless of the oxidation time.
Investigation on Cryogenic Refrigerator and Cooling Schemes for Long Distance HTS Cable
Jisung Lee,Cheonkyu Lee,Sangkwon Jeong,Jiho Park,Si Dole Hwang,Hyung Suk Yang,Se Yong Jung,Ji Hyun Lim Institute of Electrical and Electronics Engineers 2015 IEEE transactions on applied superconductivity Vol.25 No.3
<P>High-temperature superconducting (HTS) cable is one of the most prospective superconducting technologies for its low electric power transmission loss and high power density. One difficulty of practicing this technology is maintaining the HTS cable at a cryogenic temperature approximately at 70 K. The types of cryogenic refrigerators are briefly reviewed to apply in long-distance HTS cables. Recuperative-type refrigerators, such as Brayton and Joule-Thomson (JT) refrigerators, are more appropriate to satisfy the required high cooling power. The theoretical reliability of the newly proposed dual mixed refrigerant (DMR) JT refrigerator is analyzed. The cycle configuration of the DMR JT refrigerator is more complex than that of a Brayton refrigerator; however, the degradation of reliability was not significant. Furthermore, a remote operation apart from the compressor is possible in the JT refrigerator without moving components inside the cold box. This is the most desirable characteristic for long-distance HTS cable cooling. Finally, the advantage of using an oxygen and nitrogen mixture as the circulating coolant is discussed. The number of cooling stations can be reduced in a long-distance HTS cable by lowering the coolant feeding temperature.</P>