• 제목/요약/키워드: Online service satisfaction

검색결과 393건 처리시간 0.032초

시니어들을 위한 모바일 뱅킹 이용률 개선을 위한 UX 디자인 (UX Design of Mobile Banking Usage Improvement for Seniors)

  • 이종빈;변호민
    • 정보처리학회논문지:소프트웨어 및 데이터공학
    • /
    • 제12권7호
    • /
    • pp.325-332
    • /
    • 2023
  • 세계 인구가 이미 초고령화 시대에 진입하였고, 그 비율이 2050년도에 도달하면 대략 40%로 육박하게 된다. 4차 산업 혁명의 주요한 기술에 해당되는 자동화와 온라인 서비스가 시니어들에게는 아직도 많은 불편함을 주고 있으며 이러한 빠른 기술의 변화는 그들의 삶의 질까지도 위협하고 있으며 세상에서의 고립까지도 야기시키고 있다. 앞서서 언급된 다양한 온라인 서비스들 중에 특히 공공 성격이 강한 금융 서비스는 은행 점포의 급격한 감소로 온라인 서비스가 어려운 그들에게 유일한 돌파구였던 점포에서 대면으로 필요한 서비스들이 점점 사라지면서 생활의 많은 어려움을 겪고 있다. 본 연구에서는 현재 모바일 뱅킹 서비스 이용률이 대략 5%에 불가한 시니어들의 사용상의 어려움을 분석하고, 그들의 사용성을 개선하고자 시니어 맞춤형 모바일 뱅킹 디자인을 제안하고자 한다. 제안된 UX 디자인에서는 모바일 뱅킹 서비스에서 가장 많이 사용하는 송금 서비스 화면을 간결한 절차와 명확한 단계 이동과 필요한 선택만을 할 수 있도록 UX 디자인을 개선하고, 은행별 사용률을 분석하여 50대이상부터 연령대별로 3단계로 나누어 선호 은행을 사용자별로 우선적으로 화면에 표시함으로써 56 개이상의 은행 리스트 중에 원하는 은행을 선택시 발생될 수 있는 오류를 최소화 하도록 유도하는 방법을 제시하였다. 또한 개인 맞춤형 서비스를 제공하기 위해, 최근 사용한 은행을 은행 우선순위 리스트에 업데이트하도록 설계하였다. 본 연구를 통해 제시된 UX 디자인은 시니어들의 사용성 만족도 조사해 본 결과 5점중 평균 4.8점 이상의 만족도 결과를 얻을 수 있었다.

A Study on the Influence of Digital Experience and Purchase in the 4th Industrial Revolution : Focusing on Differences between Satisfied, Neutral, and Dissatisfied Groups

  • Jung, Sang Hee;Lee, Sang-Jik
    • Journal of Information Technology Applications and Management
    • /
    • 제26권4호
    • /
    • pp.51-69
    • /
    • 2019
  • One of the most considerate phenomena of the era of the Fourth Industrial Revolution is the use of digital devices. Digitalization is rapidly advancing through all areas of industry and life. Customer journey with digitalization is looking totally different from previous customer journey. The research targets were users of fashion, automobiles, cosmetics and online shopping malls. We analyzed 300 people for each valid questionnaire. The results of the study are as follows. First, it has been proven that digital experience affects positive (+) impact on purchasing intention and positive (+) impact on recommending intention and negative impact (-) on switching intent and subsequently affects positive impact (+) to purchase and incase of switching intent, negative impact (-) to purchase. Unlike traditional methods such as SPC(Service Profit Chain), the Digital experience to Purchase process Chain (DPC) has been identified to be suitable in the digital age. Second, the digital satisfied group (5 score-very satisfaction) has shown same result as above. However the digital neutral group (even though 4 score- satisfaction in five-point scale), specially in a highly competitive industry, has different from the satisfied group and 3 score-normal is same as dissatisfied group. It means that this group is that If there is a high level of attractiveness of substitute goods, there is a high possibility of switching them. It has supported Jones and Sasser [1995] that there have been two types of loyalty of true long-term loyalty and what we call false loyalty in the highly competitive industry zone which is commoditization or low differentiation, many substitutes, low cost of switching. Identifying true loyalty and false loyalty is crucial to establishing a customer experience strategy. it is necessary to actively utilize long-term digital experiences strategy to increase the total satisfaction of digital experience through all of customer purchasing journey in order to enhance the digital customer experience. It is difficult to see the effect as a one-time event. It should be scaled over the entire customer purchase process over a long period of time, which can positively affect purchase intention, recommendation intention, and conversion intention. This is also why it is difficult for second-runners to overtake first-runners in a short period.

검색 효과성에 영향을 미치는 시맨틱웹 검색시스템 품질요인에 관한 연구 (Quality Dimensions Affecting the Effectiveness of a Semantic-Web Search Engine)

  • 한동일;홍일유
    • Asia pacific journal of information systems
    • /
    • 제19권1호
    • /
    • pp.1-31
    • /
    • 2009
  • This paper empirically examines factors that potentially influence the success of a Web-based semantic search engine. A research model has been proposed that shows the impact of quality-related factors upon the effectiveness of a semantic search engine, based on DeLone and McLean's(2003) information systems success model. An empirical study has been conducted to test hypotheses formulated around the research model, and statistical methods were applied to analyze gathered data and draw conclusions. Implications for academics and practitioners are offered based on the findings of the study. The proposed model includes three quality dimensions of a Web-based semantic search engine-namely, information quality, system quality and service quality. These three dimensions each have measures designed to collectively assess the respective dimension. The model is intended to examine the relationship between measures of these quality dimensions and measures of two dependent constructs, including individuals' net benefit and user satisfaction. Individuals' net benefit was measured by the extent to which the user's information needs were adequately met, whereas user satisfaction was measured by a combination of the perceived satisfaction with search results and the perceived satisfaction with the overall system. A total of 23 hypotheses have been formulated around the model, and a questionnaire survey has been conducted using a functional semantic search website created by KT and Hakia, so as to collect data to validate the model. Copies of a questionnaire form were handed out in person to 160 research associates and employees working in the area of designing and developing semantic search engines. Those who received the form, 148 respondents returned valid responses. The survey form asked respondents to use the given website to answer questions concerning the system. The results of the empirical study have indicated that, of the three quality dimensions, information quality was found to have the strongest association with the effectiveness of a Web-based semantic search engine. This finding is consistent with the observation in the literature that the aspects of the information quality should serve as a basis for evaluating the search outcomes from a semantic search engine. Measures under the information quality dimension that have a positive effect on informational gratification and user satisfaction were found to be recall and currency. Under the system quality dimension, response time and interactivity, were positively related to informational gratification. On the other hand, only one measure under the service quality dimension, reliability was found to have a positive relationship with user satisfaction. The results were based on the seven hypotheses that have been accepted. One may wonder why 15 out of the 23 hypotheses have been rejected and question the theoretical soundness of the model. However, the correlations between independent variables and dependent variables came out to be fairly high. This suggests that the structural equation model yielded results inconsistent with those of coefficient analysis, because the structural equation model intends to examine the relationship among independent variables as well as the relationship between independent variables and dependent variables. The findings offer some useful implications for owners of a semantic search engine, as far as the design and maintenance of the website is concerned. First, the system should be designed to respond to the user's query as fast as possible. Also it should be designed to support the search process by recommending, revising, and choosing a search query, so as to maximize users' interactions with the system. Second, the system should present search results with maximum recall and currency to effectively meet the users' expectations. Third, it should be capable of providing online services in a reliable and trustworthy manner. Finally, effective increase in user satisfaction requires the improvement of quality factors associated with a semantic search engine, which would in turn help increase the informational gratification for users. The proposed model can serve as a useful framework for measuring the success of a Web-based semantic search engine. Applying the search engine success framework to the measurement of search engine effectiveness has the potential to provide an outline of what areas of a semantic search engine needs improvement, in order to better meet information needs of users. Further research will be needed to make this idea a reality.

정보시스템의 지속적 사용에서 경험의 역할에 대한 분석 (An Analysis of the Roles of Experience in Information System Continuance)

  • 이웅규
    • Asia pacific journal of information systems
    • /
    • 제21권4호
    • /
    • pp.45-62
    • /
    • 2011
  • The notion of information systems (IS) continuance has recently emerged as one of the most important research issues in the field of IS. A great deal of research has been conducted thus far on the basis of theories adapted from various disciplines including consumer behaviors and social psychology, in addition to theories regarding information technology (IT) acceptance. This previous body of knowledge provides a robust research framework that can already account for the determination of IS continuance; however, this research points to other, thus-far-unelucidated determinant factors such as habit, which were not included in traditional IT acceptance frameworks, and also re-emphasizes the importance of emotion-related constructs such as satisfaction in addition to conscious intention with rational beliefs such as usefulness. Experiences should also be considered one of the most important factors determining the characteristics of information system (IS) continuance and the features distinct from those determining IS acceptance, because more experienced users may have more opportunities for IS use, which would allow them more frequent use than would be available to less experienced or non-experienced users. Interestingly, experience has dual features that may contradictorily influence IS use. On one hand, attitudes predicated on direct experience have been shown to predict behavior better than attitudes from indirect experience or without experience; as more information is available, direct experience may render IS use a more salient behavior, and may also make IS use more accessible via memory. Therefore, experience may serve to intensify the relationship between IS use and conscious intention with evaluations, On the other hand, experience may culminate in the formation of habits: greater experience may also imply more frequent performance of the behavior, which may lead to the formation of habits, Hence, like experience, users' activation of an IS may be more dependent on habit-that is, unconscious automatic use without deliberation regarding the IS-and less dependent on conscious intentions, Furthermore, experiences can provide basic information necessary for satisfaction with the use of a specific IS, thus spurring the formation of both conscious intentions and unconscious habits, Whereas IT adoption Is a one-time decision, IS continuance may be a series of users' decisions and evaluations based on satisfaction with IS use. Moreover. habits also cannot be formed without satisfaction, even when a behavior is carried out repeatedly. Thus, experiences also play a critical role in satisfaction, as satisfaction is the consequence of direct experiences of actual behaviors. In particular, emotional experiences such as enjoyment can become as influential on IS use as are utilitarian experiences such as usefulness; this is especially true in light of the modern increase in membership-based hedonic systems - including online games, web-based social network services (SNS), blogs, and portals-all of which attempt to provide users with self-fulfilling value. Therefore, in order to understand more clearly the role of experiences in IS continuance, analysis must be conducted under a research framework that includes intentions, habits, and satisfaction, as experience may not only have duration-based moderating effects on the relationship between both intention and habit and the activation of IS use, but may also have content-based positive effects on satisfaction. This is consistent with the basic assumptions regarding the determining factors in IS continuance as suggested by Oritz de Guinea and Markus: consciousness, emotion, and habit. The principal objective of this study was to explore and assess the effects of experiences in IS continuance, with special consideration given to conscious intentions and unconscious habits, as well as satisfaction. IN service of this goal, along with a review of the relevant literature regarding the effects of experiences and habit on continuous IS use, this study suggested a research model that represents the roles of experience: its moderating role in the relationships of IS continuance with both conscious intention and unconscious habit, and its antecedent role in the development of satisfaction. For the validation of this research model. Korean university student users of 'Cyworld', one of the most influential social network services in South Korea, were surveyed, and the data were analyzed via partial least square (PLS) analysis to assess the implications of this study. In result most hypotheses in our research model were statistically supported with the exception of one. Although one hypothesis was not supported, the study's findings provide us with some important implications. First the role of experience in IS continuance differs from its role in IS acceptance. Second, the use of IS was explained by the dynamic balance between habit and intention. Third, the importance of satisfaction was confirmed from the perspective of IS continuance with experience.

O2O를 활용한 신선한 농산품 전자상거래의 지속적 사용의도에 관한 연구 (A Study on the Continuance Intention of O2O Fresh Agricultural Products E-Commerce)

  • 고위;포붕;이종호
    • 산경연구논집
    • /
    • 제10권10호
    • /
    • pp.35-44
    • /
    • 2019
  • Purpose - This study focuses on the continuance intention of O2O fresh agricultural products e-commerce. By literature review, this paper looks through the classical theories which are often applied to study use behavior and continuance intention on the electronic commerce area. Ultimately based on the expectancy theory, Technology acceptance model, success model as well as trust model, a model of the continuance intention of fresh products O2O electronic commerce application is established. Research design, data, and methodology - Among users Chinese consumers have been chosen who have use experience as the research objects. From October 2, 2018 to November 2, 2018, 685 questionnaires in total were collected by the online release and collection. Expect for the negative questionnaires, the remaining 650 pieces of data are statistically analyzed. The collected data were firstly be analyzed by SPSS Ver. 25 on its frequency, reliability and exploratory factors. Then AMOS Ver. 25 is applied to the Confirmatory Factor Analysis, Discriminant Validity and hypothesis testing of the Structural Equation Modeling. Finally, the following research conclusions could be obtained from the hypothesis testing. Results - Firstly, in the extended IS model, quality factor for hypothesis testing, service quality, information quality and delivery quality have obviously present positive influences on satisfaction respectively. Secondly, in the hypothesis testing part of ECM-ISC model and UTAUT model, all hypotheses have presented accepted results. Especially from expectation confirmation to usefulness perception, the influence factor achieves 12.603, In the hypothesis of continuance intention, the influence factor of social influence on continuance intention is 7.748 and also it is the most remarkable one. Conclusions - The results show that the service quality of O2O fresh agricultural products e-commerce has the greatest impact on satisfaction, while the perceived usefulness of consumers has the most significant impact on O2O fresh agricultural products for sustainable use intention. This thesis makes up for the blank of O2O fresh food e-commerce for sustainable use intentions, and provides a theoretical basis for consumers' sustainable use behavior, and practical enlightenment for the sustainable development of O2O fresh agricultural products e-commerce.

여성의 피부 관리실 이용 선호도 및 피부 미용 홈 케어 만족도 조사 연구 (A Study on Women's Preference for the Use of the Esthetic Shop and the Satisfaction Level of Skin Beauty Home Care)

  • 김현숙
    • 한국산학기술학회논문지
    • /
    • 제22권5호
    • /
    • pp.288-295
    • /
    • 2021
  • 본 연구는 여성의 피부 관리실 이용 선호도 및 피부미용 홈 케어 만족도 조사 연구를 목적으로 2021년 3월 11일-3월 29일 까지 255명을 대상으로 온라인과 오프라인을 이용하여 설문 조사를 실시하였다. 수집된 자료는 SPSS 25.0 를 이용하여 Cronbach's α, Frequency Analysis, chi-square test, 기술 통계, One way Anova로 분석하였다. 조사 결과 피부 관리실 이용 선호도에서 전문 피부 관리실을 이용한다고 답한 응답자(56.1%)가 가장 많았으나 20대와 사무직(57.1%)은 피부과 병원을 선호하는 것으로 나타났다. 피부 관리실 선택 시 고려사항으로는 직원들의 기술(숙련, 유행)에 대한 항목이 38.8%로 높게 나타났으며 피부 관리 행태에서 클렌징 등 기초 화장품(M=4.47)과 기능성 화장품(M=4.20) 사용이 매우 높은 것으로 나타났다. 피부미용 홈 케어 현황을 살펴보면 결혼여부는 기타(M=4.50)가 가장 높았고, 학력별로는 대졸(M=3.84)이, 직업별로는 Service Job(M=4.06)이 가장 높게 나타나고 있으므로 이에 따른 피부미용 전문 프로그램 개발 및 피부 관리실과 홈 케어를 병행할 수 있는 프로그램 개발에 대한 필요성이 높은 것으로 나타났다.

미취학 자녀를 둔 기혼 여군 장교의 일·가정 양립 지원제도 활용 정도와 재직의도 영향요인 (Utilization of Work-Family Balance Support Policy and Factors Associated with Retention Intention among Married Female Officers with Preschool Children)

  • 권조은;김광숙;박정옥;김수
    • 여성건강간호학회지
    • /
    • 제25권3호
    • /
    • pp.329-344
    • /
    • 2019
  • Purpose: This study aimed to identify utilization of the work-family support policy (WFSP) and factors affecting retention intention among Korean female military officers. Methods: This cross-sectional survey recruited 103 married female officers from the Korean Army, Navy, and Air force with preschool-aged children through convenience and snowball sampling. Via online surveys from June to November, 2018, the participants self-reported retention intention, work-family conflict, job satisfaction, and utilization of the WFSP. The data were analyzed using descriptive statistics, independent t-tests, one-way analysis of variance, Pearson's correlation coefficient, and multiple linear regression. Results: Retention intention ($22.29{\pm}5.98$) was reported at the mid-level, lower than scores reported in the literature for female workers. Work-family conflict ($32.51{\pm}5.29$) and job satisfaction ($63.10{\pm}7.45$) were above the midpoint levels. Use of maternity leave (100.0%) and parental leave (92.2%) was high, especially compared to the rates of child-care day off (20.4%) and parenting time (20.4%). 'Noticeable increases in childcare services within the army' (22.8%) was reported as the supportive measure needed the most by female military officers. Job satisfaction (${\beta}=.43$, $p{\leq}.001$), the use of parenting time (${\beta}=-0.29$, p=.002), living type (${\beta}=-.18$, p=.043), and service type (${\beta}=-.16$, p=.035) significantly influenced retention intention. Conclusions: The findings highlight the priority areas of importance within the WFSP and suggest that a family-friendly culture can improve female officers' retention intention. Accordingly, policy changes at the Ministry of National Defense improving the system to enhance a family-friendly culture in the military is expected to strengthen the retention intention of female officers and contribute to excellence in the military workforce.

국내 애니메이션 산업의 온라인 마켓플레이스 구축 필요성 연구 (A Study on the Necessity of Making Online Marketplace for the Korean Animation Industry)

  • 한상균
    • 만화애니메이션 연구
    • /
    • 통권24호
    • /
    • pp.223-246
    • /
    • 2011
  • 오늘날 문화콘텐츠 산업은 그 특성상 제조 산업 보다는 서비스 산업에 가까우며, 콘텐츠의 완성도나 품질이 높더라도 소비자의 눈높이에 맞지 않는다면 시장경쟁에서 우위를 차지하기 어렵다는 현실적인 제약을 가지고 있다. 이는 비즈니스 계획이나 활동이 콘텐츠의 완성도나 품질과 적절하게 조화를 이루었을 때라야 시장 내에서의 성공을 기대해 볼 수 있다는 뜻이며, 그만큼 글로벌 환경에서의 비즈니스 경쟁이 중요하다는 의미이기도 하다. 다시 말해, 문화콘텐츠 산업에서 콘텐츠 창작력은 당연히 중요한 것이지만, 앞으로는 유통 프로세스를 구축관리하고 부가가치가 적절하게 배분될 수 있는 시스템을 만드는 것이 보다 더 중요한 역할을 할 것이라는 의미이다. 특히나 애니메이션은 장르의 특성상 다른 콘텐츠에 비해 상대적으로 문화적 장벽의 영향을 덜 받는 장점이 있다. 이른바 문화적 할인율이 영화나 드라마와 같은 여타의 영상 콘텐츠보다 낮다는 뜻이다. 하지만 국내 애니메이션의 경우, 이러한 이점에도 불구하고 영화 산업이나 방송 산업에 비해 아직까지 산업적 인프라가 상대적으로 취약하고, 분야별 전문 인력 또한 매우 부족하여 해외유통에 있어서의 현실적 제약을 해결하기 위한 보다 근본적이며 구체적인 방안이 요구되고 있다. 이와 같은 필요성과 국내 산업이 처한 상황을 종합적으로 고려하였을 때, 가장 효율적으로 운영될 수 있는 방안이 온라인을 통한 국산 애니메이션 콘텐츠의 B2B형 마켓플레이스 구축이다. 이는 기존의 소극적인 방식에서 벗어나 온라인을 통해 보다 효과적이며 광범위한 유통방식을 선택하는 것을 말한다. 이러한 온라인 마켓플레이스가 발굴 정착된다면 국내의 다양한 애니메이션에 대한 정보를 실시간으로 전 세계의 잠재적 고객들과 공유할 수 있게 된다. 또한, 다원적인 유통창구로도 활용되어 추가수익을 창출하고 이를 통해 부가시장이 활성화되어 국산 애니메이션 콘텐츠의 보다 높은 국제적 경쟁력을 확보 할 수 있을 것으로 기대된다. 아울러 국내 애니메이션 콘텐츠산업은 질적, 양적 성장을 이룰 것이며, 기존 콘텐츠 제작자와 유통사업자간의 불공정거래 및 왜곡된 수익배분 등 후진적 유통환경 개선을 통해 선순환구조 확립에 일조하게 되어 궁극적으로는 전 세계시장에서 일정한 가치를 갖는 브랜드 자산을 형성할 수 있다. 또한 동시에 한국 애니메이션의 국제적 브랜드화를 보다 빨리 확립할 수 있는 기회가 될 것이다.

소비자가 생각하는 안경사의 전문성에 대한 인식도 조사 (A Survey on the Awareness of Consumers on the Expertise of Optometrists)

  • 한선희;김봉환;윤다빈;송정호;윤지민;김형수
    • 한국임상보건과학회지
    • /
    • 제9권2호
    • /
    • pp.1502-1510
    • /
    • 2021
  • Purpose. To investigate on the awareness of consumers on the expertise of optometrists. Methods. Data were collected and analyzed through an online questionnaire targeting 63 consumers (42 consumers over the age of 10 who wore glasses, and 21 students in the Department of Optometry). Result. As a consideration when choosing an optometrist, consumers considered the variety of products (15 persons(23.8%)), expertise such as optometry and fitting, kindness and credibility (11 persons(17.5%)). Students in the Department of Optometry of each selected expertise such as optometry and fitting, kindness and credibility (5 persons(7.9%)) and the results were high. In addition, about the main tasks of optometrists, 20 consumers (31.7%) and 9 students (14.3%)(SD 14.5±5.5) answered that they were medical technicians specializing in vision health. And the service satisfaction of the optometrist (5 point scale) was evaluated as 3.77 points for the consumers and 3.76 points for students(SD 3.77±0.01), and the reliability (5 point scale) for the consumers was 3.42 points and students 3.53 points (SD 3.48±0.06). In terms of expertise (5 point scale), the consumers scored 3.47 points and current students 3.58 points (SD 3.53±0.06). Conclusion. As a result of the study on consumer awareness of the expertise of optometrists, there was no significant difference in the perceptions of the reliability, service, and expertise of optometrists in the opinion of the consumers and students of the Department of Optometry. In terms of reliability and expertise, students in the Department of Optometry were evaluated somewhat higher than the consumers. Therefore, in order for consumers to be able to trust the expertise of optometrists in the future, it is necessary to take pride in being a medical technician specializing in vision health, and to actively promote and make efforts to inform consumers that optometrists are experts recognized by the state.

Web 2.0 블로그 위젯의 재미 요소에 대한 연구 (A Study on Fun Elements of Web 2.0 Blog Widget)

  • 최성규;김기성;장석현;황민철
    • 한국HCI학회:학술대회논문집
    • /
    • 한국HCI학회 2009년도 학술대회
    • /
    • pp.785-790
    • /
    • 2009
  • 웹 2.0환경에 중심이 되고 있는 블로그 사용자들에게 있어 웹 브라우저에서 실행될 수 있는 위젯(widget)은 자신을 표현하고, 블로그의 가치를 돋보이게 하는 도구이다. 위젯은 윈도우(Window)와 가젯(Gadget)의 합성어로 응용 프로그램을 동작시키고 결과를 화면에 표시하는 그래픽 사용자 인터페이스(GUI) 도구의 일종으로써 사용자가 원하는 서비스를 받아 볼 수 있는 기능성 프로그램이다. 또한 운영 제체(OS)나, 웹, 모바일에서 사용자에게 정보 전달 및 사용 편리성과 효율성을 제공하고 있다. 그러나 현재 위젯은 정보 전달이나 현상 표현에 초점을 마주고 있어, 사용자들이 원하는 재미를 충족시켜주지 못하고 있다. 이 연구는 웹 2.0 환경에서 사용자가 많이 사용하고 있는 위젯의 재미와 흥미를 느끼는 요소가 무엇인지를 파악하고, 위젯별 재미 요소를 분류 하고자 하는 연구이다. 위젯에서의 재미 요소에 대해 아직까지 정의된 것이 없기 때문에 제품 디자인과 게임에서의 재미 요소를 분류 및 분석을 통해 추출 하였고 추출된 결과를 사용자의 감성 상태를 대표하는 감성 어휘와 매핑을 통해 파악하였다. 그리고 위젯별 재미 요소를 알아내기 위해 블로그 사용자를 대상으로 온라인 설문을 실시하였다. 위젯 선정은 사용자가 많이 이용하고 있는 국내 위젯과 일본 위젯으로 선택하였고 5점 척도를 이용해 위젯별 재미 요소를 분류하였다. 이 결과를 바탕으로 사용자가 선호하는 재미 요소를 파악할 수 있다.

  • PDF