In conventional journals, the cost for publication is usually covered by the subscription fee paid by the subscribers is reimbursed by the academic organizations, and the copyright is transferred from the authors to the publishers when a manuscript has been approved before the actual publication. The OA journals apply contrasting concepts: the authors should pay the publication fee to the publishers and could maintain the copyrights (Gold OA: the most common form of OA). Anybody can get access to the articles without paying any cost and the reuse of them, with academic or commercial purpose, is permitted depending on the copyright extent. The OA journals may be sub-classified according to the subject of publication, payment method, or the copyrights. In platinum/diamond OA journals, the publishers pay for the publication cost and provide the literature to the readers at no cost, in which they are often supported by the external funding for the public purposes. In green OA journals, the authors can self-archive their publication in the websites or another repository to provide their literature. In bronze OA journals, a similar concept to gold OA ones except for the restricted copyright, where the reuse is not fully permitted. Along with the marked increase in the number of medical publications during the recent years, the OA publishing has grown much faster than the conventional ones. Between 1981 and 1990, 1,672,389 articles were published on WoS in the major medicine categories (S1 Table), among which, only 89,774 (5.4%) were published in the OA journals. However, between 2011 and 2020, about one-third (2,069,772 among 6,133,274 articles, 33.7%) was published in the OA journals (Fig. 1). When the OA journals were initially established, their main aim was to share the up-to-date knowledge widely, especially for the developing countries where the researchers have difficulty paying the subscription fees. In 2008, the National Institute of Health in the US stated that all research results, supported by the Institute, should be submitted to PubMed Central or be published in the OA journals [6]. In 2017, the Bill and Melinda Gates Foundation announced that it would separately create an OA publication at its own expense, when the research results supported by the foundation were published [7]. All projects supported by the European Commission’s Horizon 2020 fund were also mandated to publish their research results in the OA journals [8]. In fact, OA publishing has helped meet the explosive demand of the academic publications that the traditional subscription journals have been unable to accommodate.

Similarly, OA publishing has exhibited a steep surge in Korea. Between 1981 and 1990, only 37 articles were published in OA settings on WoS. This occupied only 5.3% of all Korean articles on WoS, and merely 0.04% of global OA publishing. On the contrary, between 2011 and 2020, the number of OA-published Korean articles was 57,072, occupying 2.7% of global OA publishing and ranked in the 11th place among all countries. More than one-third (37.4%) of WoS articles from Korea have been published in the OA journals (Table 2).

According to a recent study by Kim [9], wherein 1,275 experienced Korean researchers and authors were interviewed, 77% of the respondents stated that they were interested in publishing their works in the OA journals. Two common reasons were (1) “OA articles can be cited and read more widely (93%)”, and (2) “Research supported by the public funds should be open to the public (52%).” Meanwhile, two major reasons for not considering OA publishing were (1) “Economic burden of processing charges (57%)”, and (2) “Relatively lower quality and reputation (33%)” (Fig. 2). Most authors still preferred publishing in the conventional “Big 3” companies: Elsevier (74%); Springer (57%); and Wiley (31%), respectively. Relatively preferred OA publishers included Nature Publishing Group (15%), Multidisciplinary Digital Publishing Institute (MDPI, 13%), and Public Library of Science (PLOS, 12%), respectively.

Spam invitations from the predatory journals are typically overly polite and flattering in tone (e.g., starting with, “Dear respectful professor”). I have an experience of being trapped by a predatory journal, when I did not have any idea on this. After writing a 500-word manuscript, it was accepted quickly with enveloped invoice charging 500 USD. Though I officially requested that I did not want publication in that journal, however, the article was published in 3 months. Since then, they have sent me invoices every 3 to 6 months, up to 3 years later.

A predatory journal can be conceptually defined as one that primarily pursues profits without applying the methodology to ensure the academic quality. Beall’s criteria [10] are frequently used, which are somewhat long and have more than 20 items. Based on my personal experience, I have selected several categories that would be useful for the medical researchers (Table 3). The easiest way to avoid predatory journals is to submit manuscripts to the esteemed journals affiliated with the relevant expert societies. If alternative way of choosing the OA journals is considered, it is recommended to reference so-called “white lists”, supported by the Directory of Open Access Journals (DOAJ, available at: https://doaj.org/) or Open Access Scholarly Publishers Association (OASPA, available at: https://oaspa.org/). These are the associations of the major OA publishers supporting the librarians to ensure the quality and reputation. Currently, the DOAJ council includes Emerald publishing, MDPI, Frontiers Media, and librarians from the Royal Danish library, the University of Florida, and Virginia Tech. The OASPA boards include the Taylor & Francis group, PLOS, Hindawi, MDPI, eLife, The Royal Society, The Royal Society of Chemistry, and DOAJ. The web site named “Think, check, submit” (available at: https://thinkchecksubmit.org/) provides the guidance in choosing the legitimate journals in an easy-to-understand manner. This is a non-profit organization founded to help the researchers, and was cofounded by the publishers and the organizations including BioMed Central, Springer Nature, the Committee on Publication Ethics (COPE), Asian Council of Science Editors, Association of European Research Libraries, DOAJ, and OASPA. Their checklist is highly practical and convenient (Table 4).

Most Korean universities require their faculty to publish research work in the indexed journals as the measurement of their academic achievement. According to the aforementioned study by Kim [9], two most important factors in selecting the journals were (1) whether they were indexed in the established indexing (84%), followed by (2) the level of impact factor (67%). A nationwide investigation of 27 Korean universities [12] revealed that publishing in the SCI/SCIE-listed and Scopuslisted journals were 2–2.4 times and 1.2–1.4 times more influential than in the Korean citation index (KCI) journals. Accordingly, most Korean medical researchers are eager to publish their works in the SCI/SCIE-indexed journals. The librarians from the University of Barcelona reported that, among 944 journals which were regarded as “predatory” in Beall’s list, the proportions of being indexed in SCIE, ESCI, and Scopus were 0.95% (9 journals), 2.97% (28 journals), and 5.93% (56 journals), respectively [13]. Considering this, selecting journals based on SCIE indexedness (SCI and SCIE are no longer reported separately from 2020) seems a practical and valid option to avoid the predatory journals. It is worth noting that some predatory journals lure the authors using a fake “impact factor” or a made-up measure [14]. Hence, the authors should check whether the target journal is indexed in Journal Citation Reports (JCR) with valid impact factors via the official website (http://www.webofknowledge.com), or ask for the librarians’ assistance whenever suspicious.

Other practical advice includes the consideration of article processing charges (APC). The predatory journals usually charge lower APCs than the legitimate journals to lure the authors. Shen and Bjork [15] reported that the authors paid an average APC of 304 USD (range, 98 to 605 USD) for the predatory journals in Beall’s list. However, a recent study interviewing a large number of experienced Korean researchers found that the most common APC was 2,000 USD (the mean was 1,442 USD) [9]. It should be noted that exceptions exist. Some domestic journals, published and supported by the established associations, tend to charge much cheaper APCs than the foreign OA journals, for the benefit of their society members. For example, the APCs of a few Korean journals, as of in August 7, 2020, are between 500 and 1,000 USD: 500 USD for The Korean Journal of Internal Medicine (available at: https://www.kjim.org/authors/authors.php#8); 600 USD for Cancer Research and Treatment (available at: https://www.e-crt.org/authors/authors.php); and 850 USD for Journal of Korean Medical Science, respectively. In addition, if publication in the OA journals is considered, it is recommended to choose the major OA publishers, some of which are the councils or founders of the DOAJ or OASPA, as mentioned above.

If you have been invited to submit a manuscript by a certain journal, and it is suspicious whether the journal is legitimate, you are highly recommended to disregard this invitation. The legitimate journals typically ask the highly esteemed researchers only for their invited articles. If you are a researcher with this level of recognition, you would have enough insight to distinguish whether the journal is legitimate or not.

Beall’s initiative and list have had a significant impact in calling our attention to the issue of predatory journals that have undermined “academia,” while OA publishing has thrived. Beall seems to have a fundamentally skeptical perspective on OA publishing. In his review article [3], he stated, “OA businesses are set up to publish manuscripts rejected by top publishers, functioning like a lender of last resort” and “whitelists (e.g. JCR or DOAJ) promote the creation of predatory pay-to-publish journals to make a fortune.”

The Beall’s list has been empowered by an intriguing experiment in OA publishing performed by Science correspondent, John Bohannon [16]. In 2013, Bohannon drafted an intentionally flawed paper and submitted it to 304 fee-charging OA journals: 167 were listed in the DOAJ; and 121 were on the Beall’s list [17]. Among the 255 papers for which decision processes were completed, 157 journals accepted the paper while 98 rejected it. Among the publishers in Beall’s list, 82% of the journals accepted the bogus paper, while 45% of the DOAJ listed journals accepted it. This approach was heavily criticized, especially by the researchers who support OA publishing. Michael Eisen, a biologist at UC Berkeley and a co-founder of PLOS, pointed out that Bohannon’s experiment lacked a control group, and, hence, it could not be justified to interpret OA publishing as unreliable. He also indicated that the journal Science, which is highly esteemed, also accepted his own deeply flawed paper about arsenic in bacterial DNA [18]. Nevertheless, Bohannon’s experiment significantly affected the OA journal society. The DOAJ decided to review its list and tighten the criteria for inclusion, purging a number of journals that had accepted the fake paper [19]. The OASPA formed a committee to investigate the journals that accepted the bogus paper and dismissed two publishers from their membership (Dove Medical Press and Hikari Ltd.) [20]. The Beall’s list has been also criticized for being overly harsh, especially on OA publishers from developing countries [21]. The publishers founded or based in China, including MDPI, and an Egyptian OA publisher, Hindawi, were included in his list. Frontiers media is another major OA publisher included in the Beall’s list, though it is based in Lausanne, Switzerland. These publishers appealed heavily and were consequently excluded by the Beall’s list, and all of them serve as council members or founders of the DOAJ and OASPA.

In 2015, another experiment was conducted targeting the predatory journals by applying for a job as an editor with an intentionally faked profile. While 33% of the predatory journals in the Beall’s list accepted the application, encouragingly, 93% of DOAJ and all SCI indexed journals were not caught in the trap [22]. The Beall’s list has been closed since January 2017, partly due to the pressure from his affiliation and the legal issues raised by some OA publishers [3].

In the past, until before the era of widespread electronic publishing became possible, the publishers were responsible for the copyediting, proofreading, typesetting, printing, and distribution of the hard copies, and, therefore sharing one’s research results with others was slow and difficult. However, in modern times, the Internet and electronic processing has simplified this time-consuming processes. Simultaneously, the volume of publishing has markedly increased during the recent decades, leading to overall cost increase, which subsequently raised disputes between the librarians, researchers, and the major conventional publishers.

In 2019, 10 universities, affiliated with the University of California in the United States, whose scholarly outputs composed about 10% of all from the United States, raised a negotiation against the large Dutch publisher Elsevier for the reduction of subscription and OA publishing fees. Their perspective was, “Many professors are Editors and work for publishers without economic rewards. The copyright is taken by the publishers at the time of publication. Published papers should be subscribed with a fee from universities, some of them are supported by national taxes. If researchers are helping to publish and paying the article subscription fee separately, this is an unfair case of double payment. In addition, publishers do not incur much publishing costs due to the advancement of electronic publishing.” [23]. This negotiation between two large organizations drew great public attention, but ultimately failed. In a similar vein, the academic institutions in various countries are trying to redefine the subscription contract with the major publishers to reduce their economic burden, and to widen the academic exchange. Some publishers are proposing new forms of OA publishing that apply lower cost to selective regions or organizations [23]. In Korea, the Association of Korean University Libraries has also struggled to handle this economic burden issue, and published a statement calling for a government-level response to solve these issues in 2018 [23,24].