EXISTENCE OF PERIODIC SOLUTIONS WITH PRESCRIBED MINIMAL PERIOD FOR A FOURTH ORDER NONLINEAR DIFFERENCE SYSTEM

LIU, XIA,ZHOU, TAO,SHI, HAIPING The Korean Society for Computational and Applied M 2018 Journal of applied mathematics & informatics Vol.36 No.5

In this article, we consider a fourth order nonlinear difference system. By making use of the critical point theory, we obtain some new existence theorems of at least one periodic solution with minimal period. Our main approach used in this article is the variational technique and the Saddle Point Theorem.

EXISTENCE OF PERIODIC SOLUTIONS WITH PRESCRIBED MINIMAL PERIOD FOR A FOURTH ORDER NONLINEAR DIFFERENCE SYSTEM

XIA LIU,TAO ZHOU,HAIPING SHI 한국전산응용수학회 2018 Journal of applied mathematics & informatics Vol.36 No.5

In this article, we consider a fourth order nonlinear dierence system. By making use of the critical point theory, we obtain some new existence theorems of at least one periodic solution with minimal period. Our main approach used in this article is the variational technique and the Saddle Point Theorem.

The triply periodic minimal surface-based 3D printed engineering scaffold for meniscus function reconstruction

Lan Li,Peng Wang,Jing Jin,Chunmei Xie,Bin Xue,Jiancheng Lai,Liya Zhu,Qing Jiang 한국생체재료학회 2022 생체재료학회지 Vol.26 No.4

Background: The meniscus injury is a common disease in the area of sports medicine. The main treatment for this disease is the pain relief, rather than the meniscal function recovery. It may lead to a poor prognosis and accelerate the progression of osteoarthritis. In this study, we designed a meniscal scaffold to achieve the purposes of meniscal function recovery and cartilage protection. Methods: The meniscal scaffold was designed using the triply periodic minimal surface (TPMS) method. The scaffold was simulated as a three-dimensional (3D) intact knee model using a finite element analysis software to obtain the results of different mechanical tests. The mechanical properties were gained through the universal machine. Finally, an in vivo model was established to evaluate the effects of the TPMS-based meniscal scaffold on the cartilage protection. The radiography and histological examinations were performed to assess the cartilage and bony structures. Different regions of the regenerated meniscus were tested using the universal machine to assess the biomechanical functions. Results: The TPMS-based meniscal scaffold with a larger volume fraction and a longer functional periodicity demonstrated a better mechanical performance, and the load transmission and stress distribution were closer to the native biomechanical environment. The radiographic images and histological results of the TPMS group exhibited a better performance in terms of cartilage protection than the grid group. The regenerated meniscus in the TPMS group also had similar mechanical properties to the native meniscus. Conclusion: The TPMS method can affect the mechanical properties by adjusting the volume fraction and functional periodicity. The TPMS-based meniscal scaffold showed appropriate features for meniscal regeneration and cartilage protection.

Extended warranty model under minimal repair-replacement warranty policy

Jung, Ki Mun The Korean Reliability Society 2017 International Journal of Reliability and Applicati Vol.18 No.1

In this paper, we study an extended warranty model under minimal repair-replacement warranty (MRRW) which is suggested by Park, Jung and Park (2013). Under MRRW policy, the manufacturer is responsible for providing the minimal repair-replacement services upon the system failures during the warranty period. And if the failure occurs during the extended warranty period, only the minimal repair is conducted. Following the expiration of extended warranty, the user is solely responsible for maintaining the system for a fixed length of time period and replaces the system at the end of such a maintenance period. During the maintenance period, only the minimally repair is given for each system failure. The main purpose of this article is to suggest the extended warranty and replacement model with MRRW. Given the cost structures incurred during the life cycle of the system, we formulate the expected cost and the expected length of life cycle to obtain the expected cost rate.

Extended warranty model under minimal repair-replacement warranty policy

Ki Mun Jung 한국신뢰성학회 2017 International Journal of Reliability and Applicati Vol.18 No.1

In this paper, we study an extended warranty model under minimal repairreplacement warranty (MRRW) which is suggested by Park, Jung and Park (2013). Under MRRW policy, the manufacturer is responsible for providing the minimal repairreplacement services upon the system failures during the warranty period. And if the failure occurs during the extended warranty period, only the minimal repair is conducted. Following the expiration of extended warranty, the user is solely responsible for maintaining the system for a fixed length of time period and replaces the system at the end of such a maintenance period. During the maintenance period, only the minimally repair is given for each system failure. The main purpose of this article is to suggest the extended warranty and replacement model with MRRW. Given the cost structures incurred during the life cycle of the system, we formulate the expected cost and the expected length of life cycle to obtain the expected cost rate.

Total Carotenoid, Anthocyanin, and Sugar Contents in Sliced or Whole Purple (cv. BetaSweet) and Orange Carrots during 4-week Cold Storage

이은진,Kil-Sun Yoo,Bhimanagouda S. Patil 한국원예학회 2011 Horticulture, Environment, and Biotechnology Vol.52 No.4

Minimally processed carrot products in finger or coin shapes are increasingly popular due to their convenience. The ‘BetaSweet’ carrot is a purple carrot with a high carotenoid and anthocyanin content, sweet taste, and juicy, crisp texture. This study was performed to investigate the changes in carotenoid, anthocyanin, and sugar of the sliced purple and an orange carrot during 4 weeks of cold storage at 2℃ or 4℃, simulating the transportation and marketing period. The purple carrot contained about 200-230 μg・g-1 fresh weight total carotenoid and there was a slight decrease in the total carotenoid content during the 4-week period at both temperatures. Anthocyanin and total sugar contents were about 400-500 μg・g-1 and 70 mg・g-1 fresh weight, respectively and did not change significantly at either temperature. The orange carrots, tested for comparison,contained about 100 μg・g-1 total carotenoid and about 60 mg・g-1 fresh weight total sugar, and showed similar trend as the purple carrots during cold storage. Transfer from 2℃ to 4℃ at 2 weeks did not show significant changes in any of the parameters. Sliced carrots had about 10% to 15% less carotenoid content as compared to whole carrots, probably due to wound damage and the oxidation process. The content of nutritional compounds of the purple carrots harvested during April and June was similar to that obtained throughout the season, demonstrating that consistent quality products could be produced. Our study confirmed that the changes in quality of sliced purple carrots were minimal or negligible during the commercial marketing period of 2 weeks, if the product was handled and displayed at 4℃ or below.

A Bayesian Approach to Optimal Replacement Policy for a Repairable System with Warranty Period

Jung, Gi-Mun,Han, Sung-Sil The Korean Statistical Society 2002 Communications for statistical applications and me Vol.9 No.1

This paper considers a Bayesian approach to determine an optimal replacement policy for a repairable system with warranty period. The mathematical formula of the expected cost rate per unit time is obtained for two cases : RFRW(renewing free-replacement warranty) and RPRW(renewing pro-rata warranty). When the failure time is Weibull distribution with uncertain parameters, a Bayesian approach is established to formally express and update the uncertain parameters for determining an optimal replacement policy. Some numerical examples are presented for illustrative purpose.

ON THE LIFTING PROPERTIES OF HOMOMORPHISMS OF FLOWS

Song, Hyungsoo The Kangwon-Kyungki Mathematical Society 2004 한국수학논문집 Vol.12 No.2

The purpose of this paper is to investigate some lifting properties of homomorphisms of flows. It is shown that an almost one to one extension of a minimal proximal flow is proximal. It is also shown that a distal extension of a pointwise almost periodic flow is pointwise almost periodic.

Relative to open surgery, minimally-invasive renal and ureteral pediatric surgery offers no improvement in 30-day complications, yet requires longer operative time: Data from the National Surgical Quality Improvement Program Pediatrics

Marc Colaco,Austin Hester,William Visser,Alison Rasper,Ryan Terlecki 대한비뇨의학회 2018 Investigative and Clinical Urology Vol.59 No.3

Purpose: Performance of minimally-invasive surgery (MIS) is increasing relative to open surgery. We sought to compare the contemporary rates of short-term complications of open versus laparoscopic renal and ureteral surgery in pediatric patients. Materials and Methods: A retrospective cross-sectional analysis of the National Surgical Quality Improvement Program Pediatrics database was performed of all cases in 2014 identified using CPT procedure codes for nephrectomy, partial nephrectomy (PN), ureteroneocystostomy (UNC), and pyeloplasty, and reviewed for postoperative complications. Univariate analysis was performed to determine 30-day complications, with comparison between open and MIS approaches. Receiver operator curve (ROC) analysis was performed to determine differences in body surface area (BSA) and age for open versus MIS. Results: Review identified 207 nephrectomies, 72 PN, 920 UNC, and 625 pyeloplasties. MIS was associated with older age and larger BSA except for cases of UNC. Apart from PN, operative durations were longer with MIS. However, only PN was associated with significantly longer length of hospital stay (LOS). There was no difference in incidence of all other 30-day complications. When evaluating BSA via ROC, the area under the curve (AUC) was found to be 0.730 and was significant. Children with a BSA greater than 0.408 m2 were more likely to have MIS (sensitivity, 66.9%; specificity, 69.3%). Regarding age, the AUC was 0.732. Children older than 637.5 days were more likely to have MIS (sensitivity, 72.8%; specificity, 63.3%). Conclusions: Pediatric MIS is associated with longer operative time for nephrectomy, but shorter LOS following PN. Surgical approach was not associated with difference in short-term complications.

‘남북한 공통국어’ 교육 내용 선정의 쟁점과 과제 — 중등 문학교육을 중심으로

이상일 국어교육학회 2020 國語敎育學硏究 Vol.55 No.3

This study aimed to explore the issue and tasks in selecting the educational contents for the subject, ‘Common Korean Language of South & North(CKLSN)’. ‘Common Korean Language’ is an essential supplement to the Korean language department jointly developed and operated by the two Koreas during the unification transition period. Literature education in the CKLSN should proceed in the direction of ‘discovering’ the homogeneity of the language-cultures of the two Koreas and ‘respecting’ heterogeneity. In addition, psychological and emotional conflicts that students may experience during the unification transition should be minimized in the effort to ease and resolve differences in language and literature, which are the fundamental factors of the heterogeneity of Korean language education between the two Koreas. The main issues that could be raised in the selection of the content of literature education in CKLSN were largely divided into the ‘structuralization of content areas and systems’ and ‘selection and utilization of sanctions’. Knowledge in terms of content area and system should be minimized. A three-dimensional structure was proposed to foster attitudes through language activities. In terms of sanctions selection, it was argued that works based on strong political ideology should be strategically withheld or used on the premise of research on those works. 본 연구는 ‘통일 과도기’에 남북이 공동으로 ‘남북한 공통국어(이하 ‘공통국어’) 과목을 개발·운영한다고 전제하고, 이 과목의 교육 내용 선정 시 예상되는 쟁점과 과제를 중등 문학교육 중심으로 점검하였다. 본 연구는 공통국어의 내용 선정 시, 남북의 언어문화가 가진 동질성의 발견과 이질성의 존중을 지향하면서 통일 과도기 학생들이 겪을 수 있는 심리적·정서적 갈등을 최소화하는 방향으로 나아가야 한다고 보았다. 공통국어의 문학교육 내용 선정 시 제기될 수 있는 주요 쟁점은 ‘내용 영역과 체계의 구조화(교육과정 측면)’, ‘제재의 선정과 활용(교과서 측면)’으로 나누어 논의하였다. 교육과정 측면에서는, 지식은 최소화하고 언어활동 수행을 통한 태도의 함양을 지향하는 입체적 구조화를 제안하였고, 교과서 측면에서는 분단 이전의 작품을 중용하되, 정치이념성이 강한 이질적인 작품에 대해서는 국어교육적 활용에 대한 연구와 검증이 선행되어야 함을 주장하였다.