As mentioned above, Kawakami was the first Japanese scholar to offer a formula for visible distance and attempt to determine whether one could see Dokdo from Ulleungdo. He estimated the highest point in Dokdo at 157 meters on West Islet. Assuming that eye level was four meters (a person 1.5 meters tall standing on the deck of 2.5 meters) above sea level, he calculated the range of visibility to see Dokdo at 30.305 nautical miles (56.124 kilometers). Based upon this calculation, Kawakami argued that Dokdo is not visible from Ulleungdo as it is located about 50 nautical miles away from Ulleungdo.
To this, Lee Han-gi responded that the visible distance is as far as 93.17 nautical miles, based on the highest point of West Islet at 174 meters and Ulleungdo’s Seongin Peak at 985 meters (data from an investigation team of the Korean Alpine Club). It is thus highly possible to see Dokdo from Ulleungdo as they are 50 nautical miles apart. In addition, Lee Han-gi showed through mathematical formulas that one can see Dokdo from any point 120 meters high in Ulleungdo. Another study proved that one can see Dokdo at any point 86 meters high or higher on Ulleungdo, based upon the Pythagorean theorem and light refraction.
The fact that Dokdo is visible from Ulleungdo is also attested by numerous eyewitness accounts of Ulleungdo residents, as well as the theoretical evidence. According to these Ulleungdo residents, points where one can see Dokdo with the naked eye include Manghyang Peak behind the Dokdo Museum in Dodong-ri, Palgakjeong on the way to Seongin Peak, Naesujeon in Jeodong-ri, and Seokpo Village in Buk-myeon. The range in which Dokdo is visible extends from Sadong to Seokpo Village. Gwon Gyeong-sun noted, “I can often see Dokdo when I straighten up my back to take a rest from farm work. Some other times I can see the island when I walk in front of my yard.
Kim Seong-do, a Dokdo resident, said, “Although the location of Haengnam Lighthouse is lowland, I can see Dokdo very clearly on a fine day. On a clear day I go out to sea watching Dokdo and come back home watching Ulleungdo.” This is possible because of the total reflection phenomenon on clear autumn days.
Already 10 years ago, Kim Cheol-hwan, of Ulleungdo, took photographs of Dokdo when he saw the islet with his naked eye and made this fact public to the media. He did the same on September 6, 2004, when he took photographs of Dokdo from the Naesujeon Village. Recently, increasing numbers of photographs of Dokdo taken from Ulleungdo have been published.
To prove empirically the visible distance between Ulleungdo and Dokdo that appeared numerous times in historical records, however, we must rely upon more systematic observation. As the days when Dokdo is visible from Ulleungdo are limited, we had to establish a system to make long-term observation of the island. That was because it was essential that we obtain detailed data on Dokdo observations from points in Ulleungdo where Dokdo is visible. In recognition of this need, the Northeast Asian History Foundation set out to observe when Dokdo is visible from Ulleungdo.
The Foundation appointed the Ulleungdo resident Choi Hwi-chan as the person responsible for observation for the 18 months between July 1, 2008, and December 31, 2009. Through continuous monitoring for these 18 months at Ulleungdo, he gathered such data as the number of days Dokdo was visible, weather conditions, coordinates, and height. In addition, he took photographs of the islet with analog and digital cameras, and measured latitude and longitude with a GPS device. The usual place to take photographs was near the KBS-TV signal tower in Dodong-ri, Ulleungdo. He maintained a logbook on whether Dokdo was visible or not visible, and took photographs of Dokdo on days when it was visible.
The observers were residents of Ulleungdo who have little professional training. But they were proud of what they were asked to do, believing that they were contributing in important ways to promoting Dokdo as a part of Korean territory to the world. The following are the results of the observers:
For 18 months, the observers saw Dokdo for 20 days in 2008 and for 36 days in 2009. In 2008, November was the month during which Dokdo was visible most frequently. In 2009, that month was September. The difference in visibility days stemmed from weather conditions such as the sea fog in the spring of 2009, the long monsoon season in the same year, the unseasonably cool weather in the summer, and the unusual sea fog in the early winter. Even if the visible distance of 20 kilometers can be secured, that distance does not mean Dokdo is readily visible. We reasoned that Dokdo’s visibility was a combination of climate factors in both Ulleungdo and Dokdo. Professional analysis is required for this kind of estimation. Thus a meteorological approach has been attempted in Chapter 4.
During the investigation, the survey team took photographs of the Baekdu mountain range on the east coast of the mainland at sunset. The team even discovered that Dokdo was visible from a spot 133 meters high from the sea level at the house of Jeong Bong-gweon in Ubukdong Village (Sadong-ri, Ulleungdo). The shortest distance between Ulleungdo and the mainland was measured to be 140 kilometers from Jukbyeon (Uljin), which was visible from a spot 60 meters high on the western shore of Ulleungdo. The survey team also found that Dokdo was visible from Ulleungdo even on cloudy, rainy, or snowy days, as well as on clear autumn days.
〈FIG 6〉Spots in Ulleungdo for Viewing Dokdo in the Dokdo Visibility Study
As Ulleungdo is composed of numerous peaks whose height ranges between 600 meters and 900 meters, including the highest, Seongin Peak at 984 meters, and the coastlines consist mostly of steep cliffs, the view toward Dokdo differs widely with the slightest change in vantage point. Choi Hwi-chan, a volunteer who was responsible for observation in the Dokdo visibility study, marked the spots in Ulleungdo from which to view Dokdo〈pic 6〉.
The residents of Ulleungdo proved through 18 months of continuous observations that “Dokdo is visible from Ulleungdo.” While conducting their observations, they hoped that their attempt at proving the hypothesis could contribute to making known to the world that Dokdo is indeed part of Korea’s territory.
- [note 035]
- Kawakami (1966), op. cit., p. 281.
- [note 036]
- Lee Han-gi (1969), Territory of Korea, Seoul National University Publishing, p. 233.
- [note 037]
- Jeong Tae-man (2008), “A Mathematical Approach to the Dokdo Problem: Why Should Dokdo Be Our Land Geographically and Historically,” Dokdo Studies, pp. 166-200.
- [note 038]
- Eyewitness account by Gwon Gyeong-sun, Sadong 2-ri, Ulleung-eup, Ulleung County (July 29, 2010)
- [note 039]
- Yeungnam University Institute of National Culture (2006), Small Differences in Seeing Dokdo, pp. 222-223.
- [note 040]
- For the details of their findings, refer to Chapter 4 below, “The Meteorological Implications of Dokdo’s Visibility from Ulleungdo.”
- [note 041]
- Northeast Asian History Foundation (2009), Report on Dokdo Visibility Day Observation.