1.

論文(リポジトリ)

論文(リポジトリ)
Ludin, Gul Ahmad ; Amin, Mohammad Amin ; Matayoshi, Hidehito ; Rangarajan, Shriram S. ; Hemeida, Ashraf M. ; Takahashi, Hiroshi ; Senjyu, Tomonobu
出版情報: Electronics.  10  2021-05-18.  MDPI
URL: http://hdl.handle.net/20.500.12000/48525
概要: This paper proposes a new and surge-less solid-state direct current (DC) circuit breaker in a high-voltage direct current (HVDC) transmission system to clear the short-circuit fault. The main purpose is the fast interruption and surge-voltage and over-current suppression capability analysis of the breaker during the fault. The breaker is equipped with series insulated-gate bipolar transistor (IGBT) switches to mitigate the stress of high voltage on the switches. Instead of conventional metal oxide varistor (MOV), the resistance–capacitance freewheeling diodes branch is used to bypass the high fault current and repress the over-voltage across the circuit breaker. The topology and different operation modes of the proposed breaker are discussed. In addition, to verify the effectiveness of the proposed circuit breaker, it is compared with two other types of surge-less solid-state DC circuit breakers in terms of surge-voltage and over-current suppression. For this purpose, MATLAB Simulink simulation software is used. The system is designed for the transmission of 20 MW power over a 120 km distance where the voltage of the transmission line is 220 kV. The results show that the fault current is interrupted in a very short time and the surge-voltage and over-current across the proposed breaker are considerably reduced compared to other topologies. 続きを見る
2.

論文(リポジトリ)

論文(リポジトリ)
Grydehøj, Adam
出版情報: Okinawan Journal of Island Studies.  2  pp.1-9,  2021-03-31.  Research Institute for Islands and Sustainability
URL: http://hdl.handle.net/20.500.12000/48046
3.

論文(リポジトリ)

論文(リポジトリ)
Papoutsaki, Evangelia ; Kuwahara, Sueo
出版情報: Okinawan Journal of Island Studies.  2  pp.11-64,  2021-03-31.  Research Institute for Islands and Sustainability
URL: http://hdl.handle.net/20.500.12000/48047
概要: In this photo essay, we take you on a visual journey to Akina Village in Amami Ōshima, Japan, through the work of Futosh i Hamada, an award-winning island photographer and ecologist. Based on the artist’s Mura (2001) photographic work that documented the natural cycle of the village’s rice cultivation and the harvest festivals associated with it, we aim to explore the concept of the island’s ecocultural identity as it manifests through the artist’s and the community’s unique connection with the island nature and culture. As Akina is the last remaining village on the island where rice cultivation is still taking place, and linked to the harvest festivals, the visual documentation of these practices provides us a rare glimpse into what was once an integral part of Amami’s natural, socio-cultural, and spiritual/animistic islandscape before sugarcane was imposed on the islanders by mainland Japanese agricultural interventions and impositions. 続きを見る
4.

論文(リポジトリ)

論文(リポジトリ)
Toyoda, Yukiko ; Gabe, Masaaki
出版情報: Okinawan Journal of Island Studies.  2  pp.65-89,  2021-03-31.  Research Institute for Islands and Sustainability
URL: http://hdl.handle.net/20.500.12000/48048
概要: The Nixon administration tried to limit textile imports from Japan to protect the US industry. In return, the US would agree to return the administrative rights of the Ryukyu Islands, including Okinawa. This stood as the most important agenda item for the Sato administration in Japan. To get such a textile concession agreement from the Japanese, US offi cials had considered refusing to sign the Okinawa Reversion Treaty or to return the Senkaku Islands. However, Nixon and his advisors opposed those options since they were afraid that a confrontation over trade would spill over into defense and other security issues. Linkages among different issue areas, such as trade and security, tend to be precarious since the leverage obtained could be unclear, and various repercussions might be diffi cult to measure. When one country attempts to solve its domestic issues by linking them to other sensitive topics, domestic opposition might disrupt negotiation of the agreement or cause it to be rescinded. 続きを見る
5.

論文(リポジトリ)

論文(リポジトリ)
Iwama, Daniel
出版情報: Okinawan Journal of Island Studies.  2  pp.93-114,  2021-03-31.  Research Institute for Islands and Sustainability
URL: http://hdl.handle.net/20.500.12000/48049
概要: The repurposing of former military land is essential to the constant reformations of the US military’s immense footprint in Okinawa. The local forms of land-use planning that guide these conversions remain infl uenced by the land rent-structure that emerged out of the militarized colonial settlement of the postwar decade and the uprisings it inspired. In this article, I ask how colonial dispossession in militarized contexts shapes urban planning processes and outcomes for closed military sites. Using qualitative research in Central Okinawa, I argue that planning goals seeking to restore public access to demilitarized sites are hindered where there is a predominance of private property claims to base land. This work contributes to an understanding of planning’s colonial formations, especially as they operate through militarism, and deepens our understanding of the range of considerations that planners must make when approaching the redevelopment of militarized land in indigenous places. 続きを見る
6.

論文(リポジトリ)

論文(リポジトリ)
Mori, Keisuke
出版情報: Okinawan Journal of Island Studies.  2  pp.117-122,  2021-03-31.  Research Institute for Islands and Sustainability
URL: http://hdl.handle.net/20.500.12000/48050
7.

論文(リポジトリ)

論文(リポジトリ)
Tanaka, Shō
出版情報: Okinawan Journal of Island Studies.  2  pp.125-127,  2021-03-31.  Research Institute for Islands and Sustainability
URL: http://hdl.handle.net/20.500.12000/48051
8.

論文(リポジトリ)

論文(リポジトリ)
Okazawa-Rey, Margo ; Takazato, Suzuyo ; Natividad, Lisa Linda ; Ginoza, Ayano ; Compoc, Kim
出版情報: Okinawan Journal of Island Studies.  2  pp.129-144,  2021-03-31. 
URL: http://hdl.handle.net/20.500.12000/48052
9.

論文(リポジトリ)

論文(リポジトリ)
Kina, Ikue
出版情報: Okinawan Journal of Island Studies.  2  pp.145-149,  2021-03-31.  Research Institute for Islands and Sustainability
URL: http://hdl.handle.net/20.500.12000/48053
10.

論文(リポジトリ)

論文(リポジトリ)
Maeda, Takahiro
出版情報: 政策科学・国際関係論集 = Review of policy science and international relations.  pp.39-66,  2021-03-27.  琉球大学人文社会学部
URL: http://hdl.handle.net/20.500.12000/48287