A Historical Building Designed by Chung-Up Kim, a Pioneer of Modern Architecture

Namdaemun has always been a landmark of Seoul, no matter how many new modern skyscrapers are erected in the city. Namdaemun is a special place since it has its own history and memories that aren’t found in newly built buildings. This place serves as a setting in many Korean novels showing that it’s a real symbol of the capital of Korea. The Namdaemun-ro, a street that connects Seoul Station, Shinsegae Department Store, and Myeongdong Cathedral, was the socio-cultural center of modern and contemporary Seoul.

There is one building that has been standing in this symbolic place for a long time — it’s the Danam Tower. Danam Tower (formerly Tokyu Hotel) was designed by Chung-Up Kim, a master of Korean modern architecture. It is a high-rise building situated right next to Namdaemun, on the foot of Namdaemun-ro that leads to Namsan Mountain.

Born in Pyongyang in 1922, Chung-Up Kim studied architecture at Yokohama National University in Japan and left for Paris to work for Le Corbusier. On returning to Seoul in 1956, Kim opened his own architecture office and designed the French Embassy and the main building of Pusan National University (currently the Humanities Building). Chung-Up Kim has been known for his outstanding sculptures and also as a pioneer in Korean architecture. Though it is not well known, Kim designed many buildings in downtown Seoul, including the headquarters of Industrial Bank of Korea, the Rehabilitation Protection Center (currently Anguk Building), and the 31 Building, thus, opening the era of high-rise buildings in Korea. Many broadcasting stations and art centers in provincial cities are also works of Kim.

Danam Tower: from Tokyu Hotel to an Office Space Rental Building

Danam Tower was designed by Chung-Up Kim in 1968 and constructed by Hyundai Engineering & Construction. It was open for business in 1971. Since Danam Tower was built as a hotel and used for a long time, some people in Namdaemun Market still call it the Tokyu Hotel.

In 1962, the Korean government established the International Tourism Organization (currently the Korea Tourism Organization) and stepped forward to streamline the management of hotels. In the 1970s, the tourism industry became the core national strategic industry, and several measures were taken to promote the hotel business, some of them including funds for hotel management, reduced electricity & entertainment tax, and simplified licensing procedures.

At the time when the domestic capital base wasn’t abundant, direct foreign investments were active to attract foreign capital. The Tokyu Hotel was also constructed in this manner — as a joint venture between Korea’s Danam Industry and Japan’s Tokyu Railways Company, Ltd. At first, the building wasn’t well-received by the public because it was a first high-rise building constructed right next to Namdaemun, the National Treasure of South Korea. After being operated as a hotel for about 12 years, the building was renamed Danam Tower and has been used as an office space rental building.

A Simple, Straightforward Design and Remodeling Using PosART as Interior Material

There are two revolving doors at the entrance of the Danam Tower that features a magnificent cantilever canopy extending all the way to the sidewalk and a wide staircase below. The building has a rather simple space arrangement — with Starbucks and an optical store located on the first floor, and identical office spaces from the second to the 26th. In the initial design, Chung-Up Kim came up with a cantilever structure that would support the entire 89-meter building with just two columns but with the construction technology of the time, realizing it was a nearly impossible task. Hence, the plan was modified to place eight columns, two on each side, giving the bland square building a more impressive design. The center of the square plane features seven elevators, staircases, restrooms, and ducts. The interior of the office spaces is vast, with no columns or walls, as the exterior columns are supporting the entire structure. Glass windows are everywhere, providing a panoramic view of Seoul Station, Myeongdong, Inwangsan Mountain, and Bukhansan Mountain.

[Architect’s Pick: INNOVILT PosART Exterior & Interior Materials]

In 2018, the Danam Tower underwent large-scale remodeling. Deteriorated parts were renovated and the outer wall, which had been finished with ivory-colored exposed concrete, were covered with black terracotta panels, glass, and aluminum sheets. The lobby, which is considered the ‘face’ of a building, took on a new look as well. The former lobby, where an old chandelier hung on the curved ceiling, was reborn with a straightforward and sleek-looking appearance. Selecting the materials for the renovation was an important task, considering that the building was a historical one, and after careful reflection, PosART interior materials with Basaltina prints were selected for the walls. PosART is a new construction material that POSCO C&C has successfully commercialized for the first time. Inkjet printing technology on POSCO steel becomes PosART, and the material used here was specifically PosART Marble. It embodies the texture and looks of natural marble while providing easier construction and renovation at a lower cost. Radon, which is a defect found on synthetic marble, isn’t a problem here, and another feature is that it is a sustainable material. Also, PosART enables custom printing without additional molds for creating patterns or processing.

Although the material is still unfamiliar to architects as of present, it is expected to serve as an appropriate alternative to conventional construction materials, excelling in both functional and aesthetic features. In the case of Danam Tower, a dry construction method was applied, leaving the existing marble tiles as they are and installing an anchor on top to attach the PosART. In this way, there was no need to demolish the walls of the main building, therefore making the construction easier and shortening the period.

A cornerstone reading, “Placed on May 15, 1968,” can be seen when you come outside the building. The tower’s official logo is an abstract image of the building itself with “since 1970” written underneath. An architectural model created at the time of the building’s completion is displayed on one side of the lobby. The blueprint is preserved as well. All of these exhibit how much pride and affection the owner has for the building. Apparently, an employee who joined the Tokyu Hotel as a concierge is still working here as a parking management employee. There might be mixed evaluations following the remodeling plan, which is a complete transformation from its former structure. However, one thing is for sure — the building has become much cleaner and safer. Let’s hope that the now-sophisticated historic and iconic building will remain in its place for a long, long time.

▲ Source: Seoul National University Library Kwanjeong White Paper (2016)

The main building of the Central Library, located in the heart of Seoul National University (SNU) Gwanak campus, was completed in 1975 with the design from Seung-woo Lee. Built to reflect modernism, which was at its height at the time, the building has been well used for over 40 years without much change. It is not necessary to give many titles such as “The best” or “Having the largest number of books” to SNU’s library since it is a significant place with history, where countless students have passed. However, as times changed, more was expected from the library, and the need for expansion became apparent. Bookshelves were lacking space, and the reading rooms were also becoming too small to provide for all the flooding students. So, in 2013, SNU decided to construct “Kwanjeong Building” as an extension building of the central library.

▲ Source: Seoul National University Library Kwanjeong White Paper (2016)

A Large Open Indoor Space

SNU Library Kwanjeong faced some challenges in its construction — like in all other buildings — since it had to meet the following conditions: 1. The Kwanjeong Building had to be directly connected to the main building, and 2. the central stairway between the library and the student center, and the pathway to the east of the library had to be preserved in its original state. To achieve this task, SNU had no choice but to select the narrow piece of land between the Central Library and the College of Pharmacy as the construction site for the expansion. Instead of initiating the original plan, which was to build the library higher, an L-shaped design plan was selected, covering the right-hand side and upper part of the Central Library. This was a measure to secure the scenic view that stands behind the library as well as to keep with the height restrictions of Gwanaksan Mountain. The construction method adopted here leaves a gap between the main building’s rooftop and the Kwanjeong Building, giving it an illusion — as if a new floor was added to the main building.

The Kwanjeong Building took a horizontally long-form, reaching 165 meters to secure maximum interior space. The floor plan of the sixth, seventh and eighth floors, shows that there aren’t any columns or walls passing through the middle, other than the pillar located near the elevator. The sixth floor consists of a multimedia plaza and a computer lab, and reading rooms are located on the seventh and eighth floor, so these three floors are where many students are likely to use at all times. Since there aren’t any columns here, the students can feel much comfortable and a sense of openness as well.

A truss — weaving linear frameworks into triangular nets to withstand heavy weight — structure reaching 112.5 meters wide is supported by the two core mega columns standing at both ends of the building. In reality, using a long span truss structure in a large scale building is quite rare. The key to realizing this structure is POSCO’s high performance construction steel called HSA 650(High-performance Steel for Architecture 650). With a yield strength of 650 MPa and tensile strength of 800 MPa, HSA650 is capable of supporting a weight of 80 kg per 1㎟. Simply put, the SNU Library Kwanjeong is an architecture where excellent materials meet construction techniques.

▲ The outer wall of Kwanjeong was made with a trapezoidal module curtain wall. For the purpose, the Steel Curtain Wall was selected, since it enables atypical designs and shows higher structural performance compared to other materials.

A Facade Filled with the Lights of the Mountains and Sky

Besides its structural merits, Kwanjeong Building catches the eye with its shining exterior. Tae-Yong Yoo, the architect in charge of the project, mentioned that the concept of the design was about “light” — something that has been and will be existing in the future as well. He said, “I started designing by setting a small architectural element that projects light. And this element was repeated to make up a whole.” His intentions are well displayed on the building facade, the exterior of the building. The exterior wall was built by applying the steel curtain wall and anodizing panels — a plated panel with a film that is produced while oxidizing aluminum surface — in a repetitive manner. These panels were tilted to 16 degrees considering that they highly reflect the strong summer sun. So this exterior wall is capable of reflecting and letting in sunlight at the same time.

[Architect’s Pick : INNOVILT Steel Curtain Wall]

Curtain walls aren’t new to modern architecture. However, due to structural issues, they need to be used carefully in the case of high buildings like Kwanjeong (4.5 meters). Especially if the exterior wall is to show an atypical design, a curtain wall made of steel would be most appropriate choice. In the case of Kwanjeong, the frames of the curtain wall that hold the glass and anodizing panels are slim and neat-looking. This is possible because they are INNOVILT Steel Curtain Wall made with POSCO’s World Top Premium Product, ‘PosMAC’. PosMAC is a ternary alloy coated steel composed of zinc, magnesium, and aluminum. When exposed, the coating forms a highly stable and dense film layer called “Simonkolleite.” This enables the product to demonstrate an extra protective layer — a ternary alloy layer whose density is much higher than that of conventional galvanized steel sheet. PosMAC is 10 times more corrosion-resistant than conventional steel.

The facade was made to reflect the sunlight from early morning till sunset, and relieve the heaviness it might impose on the overall landscape. The spacious indoor area with cores on each side, and the harmony of glass and anodizing displayed on the exterior with a slim well-finished frame might be considered as key features of SNU Library Kwanjeong. And INNOVILT Steel Curtain Wall plays a hidden role behind the scenes here.