The Korean Journal of Urology (KJU) is the official English-language open access journal of the Korean Urological Association. It is a peer-reviewed, monthly publication covering clinical and basic science information relevant to physicians and researchers in the field of urology. It was first published in 1960. The Korean title of the journal had been the Taehan Pinyogikwa Hakhoe chi (ISSN 0494-4747). The journal was renamed the Korean Journal of Urology (ISSN 2005-6737) to increase its international recognition in February 2009. It began to be published in English only from the first issue of 2010 to provide invaluable information to physicians, researchers, and laypersons worldwide. It was included in PubMed Central and PubMed in April 22, 2010, so that all papers from 2010 became freely accessible through the internet. It has been indexed in Scopus back through the 2005 issues and in the Korean Medical Citation Index (KoMCI) since 2000. A digital object identifier (DOI) was added beginning with the 2005 issues. Starting in 2013, audiovisual materials are now linked with YouTube via a quick response code (QR code) and social networking services have been activated.

Whether open access journals receive more citations than non-open access journals remains under debate. In a recent comparison study, open access journals were found to receive almost the same number of citations as subscription journals in the field of biomedicine [1]. It is this author's belief that inclusion in PubMed is more important than open access for increasing citations of medical journals, because PubMed is still the primary search tool for most medical researchers. Google Scholar is the most powerful search tool for a variety of research fields; however, the medical field differs. Almost 3 years have passed since the KJU was first included in PubMed Central/PubMed. Therefore, it is time to check whether the number of citations has increased. It would also be interesting to gather a variety of bibliometric indicators to understand the present position of the KJU in the field of urology. Among various citation indicators, the 2-year impact factor, SCImago Journal Rank (SJR), 2-year impact index, Z-impact factor (ZIF, impact factor excluding self-citation), and Hirsch Index (H-index) were referenced or calculated from Web of Science, Scopus, SCImago Journal & Country Rank, KoMCI, KoreaMed Synapse, and Google Scholar [2-7]. These findings will provide insight into how to manage the journal to obtain an elite reputation among not only urologists but also researchers in related areas.

The chronological total citations in Web of Science and KoMCI Web are shown in Fig. 1. The number of publications per year showed a gradual decrease, as did the total number of citations; however, the total citation number from Web of Science began to increase beginning in 2011. Data for the 2012 total citations were not yet available from KoMCI at the time of writing.

The impact factor from Web of Science and the impact index from SCImago Journal & Country Rank are presented in Fig. 2. The impact factor from Web of Science and impact index from SCImago Journal & Country Rank began to increase dramatically beginning in 2011. The impact factor and Z-impact factor from KoMCI are presented in Fig. 3. The impact factor in KoMCI fluctuated; however, there was consistency in the ZIF from KoMCI. The impact factor from KoMCI included self-citation. If the 2012 impact factor from Web of Science (0.78) was applied to the 2011 JCR, KJU's ranking in the nephrology-urology category was in the upper 84.9% (62/73). If the nephrology category journals were excluded, the ranking was in the upper 80.0% (28/35). Meanwhile, the SJR ranking in the urology category was in the upper 58.5% (31/53). The difference between the ranking of the impact factor and that of the SJR is based on the greater number of urology journals in Scopus with fewer citations.

The chronological SJR of three journals from Asia including the KJU are compared in Fig. 4. The International Journal of Urology is the official English-language journal of the Japanese Urological Association. The International Journal of Urology is published by Wiley-Blackwell on behalf of the association. It is searchable from PubMed but not from PubMed Central. The Indian Journal of Urology is the official journal of the Urological Society of India and is published by Medknow Publications and Media Pvt. Ltd, of which the full text from the 2007 volume is available in PubMed Central. From the Web of Science citation frequency, the country of researchers citing KJU was compared between the Korean or English volumes and the English only volumes (Fig. 5). The total number of citations in the Web of Science citing KJU was 396 times for the period up to 2009 out of a total of 6,912 papers (5.3%) and 347 times for the period from 2010 to 2012 out of a total of 481 papers (72.1%). Thus, in just 3 years, the KJU has had about the same number of citations as in its entire previous 50-year publication history since 1960. The years of citation of the two periods are compared in Fig. 6. There was a dramatic increase in the citations in 2012 for papers in English. The publication types of citing papers were also compared between the two periods (Fig. 7). The portion of review articles was greater in the latter period (2010-2012) than in the former one (1960-2009).

The H-index from the Web of Science was 8 and the most frequently cited papers and the number of citations are presented in Table 1. The H-index from Scopus was 10, which is presented in Table 2 along with the most frequently cited papers. The H-index from KoMCI was 12 (Table 3). The H-index by DOI from KoreaMed Synapse was 9 (Table 4). The H-index from Google Scholar was 18 (Table 5).

We can see the rapid increase in citation indicators such as the impact factor and annual total citations by SCIE journals after the language of the KJU was changed to English and the journal was included in PubMed Central/PubMed in 2010. We can see these kinds of phenomena consistently with other medical journals published in Korea. For example, the citation frequency of the Korean Journal of Internal Medicine by SCIE journals increased dramatically after inclusion of that journal in PubMed Central [9]. In anticipation of these phenomena, publishers of many medical journals in Korea have begun to switch their language to English to add their journals to PubMed Central/PubMed. The strategy of changing to English can be said to be successful with regard to citation frequency by international researchers. The quality of the KJU had been underestimated in the past owing to the language barrier. If there was a language barrier, or the journal wasn't indexed, researchers simply couldn't find or read the articles. One can imagine a very high quality journal existing that people could not read because of language.

Although the total citation count from KoMCI decreased, because that citation count is a measure of citations by journals from Korea, the total citation count from the Web of Science increased dramatically since 2011 (Fig. 1). The impact factor and impact index have also increased significantly although the number of papers published annually has decreased each year since 2010 (Fig. 2). This is believed to be the result of the PubMed Central/PubMed effect. The difference in the impact factor and ZIF from KoMCI is due to the fact that there are only three journals in the field of urology in KoMCI: the International Neurourology Journal, Korean Journal of Andrology, and KJU. The number of papers from KJU is two times of that of the two other journals, so that most of the local citations originate from KJU itself. In the comparison of the three urology category journals from Asia, the English language journal International Journal of Urology published by the Japanese Urological Association showed the highest SJR. Next was the Indian Journal of Urology, which is also indexed in PubMed Central/PubMed. KJU ranked third among these journals by its SJR. However, according to the speed of the progress of KJU, the KJU has the potential to achieve a higher SJR very soon (Fig. 4).

KJU has a history of 54 years of publication. Interestingly, the citation number of papers from 1960 to 2009 by SCIE journals was 396 and that from 2010 to 2012 was 347. This is likely due to the listing in PubMed Central/PubMed. For the papers from 1960 to 2009, more than half of the citations were made by Korean researchers (51.5%), whereas for those from 2010 to 2012, only 14.1% of the citations were by Korean researchers. Among the countries citing the KJU, researchers from the United States have cited KJU most frequently in recent years (Fig. 5B). In Fig. 6, it can be seen that the citation frequency of the English papers increased sharply from 2010 to 2012. In the comparison of types of articles citing the KJU, a larger proportion of review articles (21.5%) was found for 2010-2012 KJU papers, whereas the proportion of review articles for the 1960-2009 KJU papers was 12.0%. This difference implies that if any papers are written in English and indexed in PubMed Central/PubMed, their chance of being cited by review writers increases such that writing papers in English is very important (Fig. 7).

Recently, of the various citation indicators for researchers, the H-index has become more important for the evaluation of research activity. It is still not common to use the H-index to measure the prestige of a journal, because the impact factor is the traditional indicator. However, the impact factor usually refers to the 2-year impact factor to determine if any journal is included in very rapidly evolving fields such as genomics and stem cell research. The H-index can be used to assess journal prestige because the journals with a long history that publish many papers score highly. Use of any of the citation indicators alone, however, provides only a limited perspective. The H-indices of KJU from the Web of Science and Scopus were 8 and 10, respectively, which are meaningful values (Tables 1, 2). The H-index calculated by DOIs from KoreaMed Synapse was 9 (Table 3). Because the DOIs were added only for issues from 2005 to the present, the H-index may increase if all previous papers from the launch in 1960 were provided with DOIs. The H-index of 12 in KoMCI is also a much higher value because the KoMCI is a citation database of Korean medical journals beginning in the year 2000. It can be said that citation by papers from Korea occurred more than by papers from international journals until now (Table 4, Fig. 6). The H-index from Google Scholar was 18. Google Scholar comprises all issues of the KJU from the launch in 1960 to the present. Thus, Google Scholar provides the most accurate picture of prestige out of the five databases. The H-indexes of the Korean Journal of Internal Medicine from the Web of Science, Scopus, and KoMCI were 14, 16, and 5, respectively [9]. The difference in the H-index between the Korean Journal of Internal Medicine and KJU originates from the fact that the former has been written only in English and indexed in Medline/PubMed since 1986, although the number of papers from the former is less than for KJU.

It is worth considering what kinds of publications are cited most frequently. Of the papers ranked in the H-index of the five databases, only two papers were review articles. One publication of the type "illustrated surgical technique" was also included. The others were all original articles. Therefore, it can be said that original articles and reviews are the main source of citations, rather than case reports. If an "illustrated surgical technique" provides a recently developed technique, there is a chance of frequent citation by other surgeons. Out of the articles with higher citations in the H-index tables, three papers in the Web of Science tables corresponded to those in SCOPUS (Tables 1, 2). This is because SCOPUS includes KJU from 2005, whereas the Web of Science does not. There is a large proportion of self-citation by KJU in Scopus. Six of 12 papers from the KoMCI table corresponded to papers in the Google Scholar table (Tables 3, 5). Three of 9 papers from the KoreaMed Synapse tables corresponded to papers in the Google Scholar table (Tables 4, 5). This can be explained by the fact that KoMCI, KoreaMed Synapse, and Google Scholar contain KJU from 2000, 2005, and 1960, respectively. Two of 8 papers from Web of Science corresponded to papers in the Google Scholar table (Tables 1, 5). This is possible because Google Scholar has indexed all issues of the KJU.

The citation indicators of the KJU vary according to the database. The strategy of switching to an English-language format allowed KJU to be cited more frequently by international researchers after being indexed in PubMed Central/PubMed. The 2012 impact factor ranking manually calculated from Web of Science corresponds to the upper 84.9%; meanwhile, the 2011 SJR ranking corresponds to the upper 58.5%. Those values will increase rapidly year by year because KJU is an open access journal indexed in most of the well-known databases. The H-index of 8 from the Web of Science is also a remarkable achievement. To be cited more frequently, good original articles and high-quality review articles should be contributed. Because more than 85% of the citations are from international researchers, KJU is already established as an international journal. There will be no obstacles to becoming a top-ranking urology journal if the present editorial policy is maintained consistently, including the application of social networking services and YouTube.