• ETRI Journal
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• 제39권6호
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• pp.794-802
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• 2017

In this paper, a wireless powered communication network (WPCN) consisting of a hybrid access point (H-AP) and multiple user equipment (UE), all of which operate in full-duplex (FD), is described. We first propose a transceiver structure that enables FD operation of each UE to simultaneously receive energy in the downlink (DL) and transmit information in the uplink (UL). We then provide an energy usage model in the proposed UE transceiver that accounts for the energy leakage from the transmit chain to the receive chain. It is shown that the throughput of an FD WPCN using the proposed FD UE (FD-WPCN-FD) can be maximized by optimal allocation of the UL transmission time to the UE by solving a convex optimization problem. Simulation results reveal that the use of the proposed FD UE efficiently improves the throughput of a WPCN with a practical self-interference cancellation capability at the H-AP. Compared to the WPCN with FD H-AP and half-duplex (HD) UE, FD-WPCN-FD achieved an 18% throughput gain. In addition, the throughput of FD-WPCN-FD was shown to be 25% greater than that of WPCN in which an H-AP and UE operated in HD.

• Mass Spectrometry Letters
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• 제12권4호
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• pp.152-158
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• 2021

Electrospray ionization (ESI) and ion mobility spectrometry-mass spectrometry (IMS-MS) were employed to investigate the solvated structures of ionic species in the lithium iodide electrolyte solution in the gas phase. The Li⁺I^-Li⁺ triple ion and single standalone Li+ ions solvated by 1,4-dioxane were successfully generated and observed by ESI-MS under the influence of dioxane vapor at the inlet region. Under the present experimental condition, (1,4-dioxane)_m·Li⁺ complex ions (m = 1, 2, and 3) and a (1,4-dioxane)·Li⁺I^-Li⁺ complex ion were observed, which were further examined by IMS to investigate their structures. The presence of multiple structural isomers was confirmed, which accounts for the endothermic conformational transition of 1,4-dioxane from a chair to a boat to achieve bidentate O-donor binding to Li⁺ and Li⁺I^-Li⁺. Further structural details critical for the ion-solvent interactions were also examined and discussed with the help of density functional theory calculations.

• International Journal of Internet, Broadcasting and Communication
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• 제13권2호
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• pp.127-135
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• 2021

The goal of this study was to explore the use of multiple SNS platforms and determine whether the number of used platforms affects one's online self-presentations across the said platforms and if there is any difference in one's online and offline self-presentations based on how many SNS platforms are used. This work studied online self-presentations, compared the on/offline ones and tried to find out if the inconsistencies of one's own (observer's) self-presentations both online (across platforms) and on/offline affected the observer's impression formation (likability, trustworthiness and hypocrisy) of others. The study also aimed to find out if the impression of the others' inconsistency both online and offline would differ based on the level of intimacy between the observer and the discussant. Three levels of intimacy were studied in order to do this: friends, acquaintances and strangers (online-only friends). The results showed that the more platforms people used the more inconsistent their online self-presentations got. Even though the results of the study showed barely significant relationship between the number of SNS accounts and one's online and offline self-presentation, and partial connection between observer's inconsistent self-presentations and impression formation of others, interestingly enough, the results managed to find significant differences between the impressions based on the level of intimacy between the observer and the discussants.

• 아태비즈니스연구
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• 제13권3호
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• pp.93-118
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• 2022

Purpose - Export marketers may have incentives to attempt real earnings management to avoid low reported earnings. Therefore, we attempted to verify the relationship between cost stickiness and real earnings management in the context of export marketing. Design/methodology/approach - Data were collected from exporters that settle-accounts in December excluding financial businesses listed on the stock market from 2015 to 2019. Multiple regression analysis were employed to analyze the data. Findings - The results showed that there is a negative relationship between cost stickiness and real earnings management. In addition, the results showed that export marketers little attempt to offset the cost inefficiency caused by the increase in expense because of cost stickiness with opportunistic management activities through real earnings management. Rather, as the level of real earnings management appears lower, exporters showing cost stickiness are expected to report management performance based on actual marketing. Furthermore, exporters with a high level of managerial centrality or high managerial overconfidence little attempt to offset cost inefficiency caused by cost stickiness with real earnings management activities. Research implications or Originality - Our study is the first to investigate the quality of earnings information of exporters with cost stickiness. Based on the results, we suggested efficient marketing strategies for exporters.

• 한국전문물리치료학회지
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• 제29권3호
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• pp.200-207
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• 2022

Background: The oxygen uptake efficiency slope (OUES) is the most important index for accurately measuring cardiopulmonary function in patients with acute ischemic heart disease. However, the relationship between the OUES variables and important cardiopulmonary function parameters remain unelucidated for patients with acute ischemic heart disease, which accounts for the largest proportion of heart disease. Objects: The present cross sectional clinical study aimed to determine the multiple relationships among the cardiopulmonary function variables mentioned above in adults with acute ischemic heart disease. Methods: A convenience sample of 110 adult inpatients with ischemic heart disease (age: 57.4 ± 11.3 y; 95 males, 15 females) was enrolled at the hospital cardiac rehabilitation center. The correlation between the important cardiopulmonary function indicators including peak oxygen uptake (VO₂ peak), minute ventilation (VE)/carbon dioxide production (VCO₂) slope, heart rate recovery (HRR), and ejection fraction (EF) and OUES was confirmed. Results: This study showed that OUES was highly correlated with VO₂ peak, VE/VCO₂ slope, and HRR parameters. Conclusion: The OUES can be used as an accurate indicator for cardiopulmonary function. There are other factors that influence aerobic capacity besides EF, so there is no correlation with EF. Effective cardiopulmonary rehabilitation programs can be designed based on OUES during submaximal exercise in patients with acute ischemic heart disease.

• 한국인터넷방송통신학회논문지
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• 제23권6호
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• pp.133-137
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• 2023

본 논문에서는 반려동물 AI 진단, 동물병원 찾기, 스마트 가계부, 커뮤니티 기능을 하나로 모은 '반려동물 종합관리 어플리케이션'을 개발하였다. 해당 어플리케이션은 여러 기능을 각각의 다른 어플리케이션으로 사용해야 하는 사용자의 불편함을 해소할 수 있으며, 사진을 통해 쉽게 반려동물 AI 진단 서비스를 이용할 수 있고, 크롤링을 이용한 동물병원 정보 제공과 주변의 동물병원 찾기, OCR 텍스트 추출 기법으로 영수증을 스캔할 수 있는 스마트 가계부, 어플리케이션 사용자 간의 커뮤니티 기능을 지원한다. 본 어플리케이션을 사용함으로써 반려동물의 건강, 소비내역 등 양육에 필요한 정보를 하나의 시스템으로 관리할 수 있게 된다.

• Journal of Information Technology Applications and Management
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• 제31권1호
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• pp.1-9
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• 2024

Predicting the spread of COVID-19 remains a challenge due to the complexity of the disease and its evolving nature. This study presents an integrated approach using the classic SIR model for infectious diseases, enhanced by the chemical master equation (CME). We employ a Monte Carlo method (SSA) to solve the model, revealing unique aspects of the SARS-CoV-2 virus transmission. The study, a first of its kind in Korea, adopts a step-by-step and complementary approach to model prediction. It starts by analyzing the epidemic's trajectory at local government levels using both basic and stochastic SIR models. These models capture the impact of public health policies on the epidemic's dynamics. Further, the study extends its scope from a single-infected individual model to a more comprehensive model that accounts for multiple infections using the jump SIR prediction model. The practical application of this approach involves applying these layered and complementary SIR models to forecast the course of the COVID-19 epidemic in small to medium-sized local governments, particularly in Gangnam-gu, Seoul. The results from these models are then compared and analyzed.

• Journal of Gastric Cancer
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• 제8권4호
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• pp.198-203
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• 2008

목적: 다발성 조기위암은 전체 조기위암 중 4.5~11.7%를 차지한다. 본 연구는 다발성 조기위암의 임상병리학적 특징을 조사 분석하여 그 의의를 알아보고 치료방침의 수립에 도움이 되고자 시행하였다. 대상 및 방법: 1994년 1월부터 2004년 12월까지 11년간 연세대학교 의과대학 외과학교실에서 위선암으로 진단받고 근치적 위절제술을 시행한 2,281예의 조기위앙을 대상으로 의무기록을 후향적으로 조사 분석하였다. 결과: 다발성 조기위암은 총 91예(4.0%)였으며 2개의 병변이 81예, 3개가 9예, 4개가 1예였다. 총 102예의 보조병변 중 64예(62.7%)는 크기가 10 mm 이하였으며 83예(81.4%)는 주병변과 같은 부위에 위치하였다. 가장 흔한 조직학적 분류는 분화형으로 52예(57.1%)였다. 점막암은 49예(53.8%)였으며 점막하층암은 42예(46.2%)였고 림프절 전이는 6예(6.6%)에서 발견되었다. 단발성 조기위암과 비교하였 때 전체 생존율에서 통계학적으로 유의한 차이가 없었다. 결론: 다발성 조기위암은 단발성 조기위암과 임상병리학적으로 매우 유사하며 생존율에서도 차이가 없었다. 그러므로 다발성 오기위암의 치료에 있어서 일반적인 조기위암의 치료지침에 준한 방법을 적용할 수 있으며, 조기위암의 수술 전후 잔위에 보조병변을 남기지 않기 위하여 세심한 주의가 필요하다.

• 공학논문집
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• 제4권1호
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• pp.5-22
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• 2002

인터넷이 급속도로 발전하고 일반 텍스트 환경의 인터넷 서비스들의 WWW(World Wide Web)환경으로 바뀌어 가면서 쉬운 사용 환경으로 인한 인터넷 응용 서비스의 사용자들도 급속히 증가하고 있다. 따라서, 사용자들이 인터넷을 이용하면서 상대방에게 메시지를 보낼 수 있는 전자 메일 서비스를 이용하는 경우도 크게 증가하고 있다. 웹 기반 전자우편 시스템은 계정과 서비스를 제공하는 서버와 사용자와의 인터페이스 역할을 하는 클라이언트로 구성되며 웹 브라우저가 클라이언트의 역할을 담당한다. 즉, 일반 메일서버에 계정을 만들 수 없는 일반 사용자들이 웹 환경을 통하여 메일서비스를 제공받을 수 있도록 하는 것이다. 본 논문에서는 웹을 기반으로 하는 전자 우편 시스템을 설계하였으며, 인터넷 익스플로러(Internet Explorer)를 기반으로 하는 사용자 환경과 리눅스 시스템을 기반으로 기존 전자 우편 시스템의 문제점을 해결하고 저렴한 가격으로 큰 기대효과를 만족시켰다. 스팸으로 등록된 메일 처리, 다중 메일 처리 등을 통한 효율적인 사용자 편의성을 제공하고, 메일의 폭주와 사용자의 급증으로 인한 시스템 저하 현상을 극복하는 효율적인 메일 서비스 엔진을 구현해서 시스템의 안정성을 제공하는 전자 우편 시스템을 개발한다.

• 한국실내디자인학회논문집
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• 제25권1호
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• pp.115-123
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• 2016

In the turn of the twentieth century, Vienna emerged as a great cultural centre that stood at the forefront of developments in music, psychology, and the natural sciences. Equally influential, and still tremendously popular today, are the designs of the Wiener $Werkst{\ddot{a}}tte$ a group that was at the heart of the city's cultural scene and whose collaborators included such luminaries as the architect Josef Hoffman and the designer Koloman Moser under the slogan of Gesamtkunstwerk. The term "Gesamtkunstwerk" was introduced in the romantic period. It describes the desire for and practice of combining various art forms into a whole, such as performances that combine text, visual arts, various design and architecture. Richard Wagner was one of the early theorists of the concept, inspiring many modernist artists. As a co-founder of the Wiener $Werkst{\ddot{a}}tte$, Josef Hoffmann had a decisive influence on modern Viennese architecture and Interior design on the basis of the concept of Gesamtkunstwerk. In this view point, this study is to analyze about the generative background and design characteristics of gesamtkunstwerk advocated Wiener $Werkst{\ddot{a}}tte$. Josef Hoffmann was by all accounts a very successful architect and Interior designer in Vienna. His influence would undoubtedly have been felt simply because of his talent and energy. His special ability to range across multiple domains, coupled with a willingness to collaborate with other artists has created a synthesis and synergy that is compelling to this day.