Although several methods have been used to capture the motion of workers at construction sites to improve productivity or safety during construction projects, collecting data by image analysis and discriminating between motions are timeconsuming processes. Therefore, it is difficult to use such methods to detect the motion of several workers or over a long time period. The authors applied an accelerometer to capture motion; this apparatus has been used in the health and medical fields. A small, light accelerometer and a simple discrimination program allowed the authors to determine whether a worker was active or inactive based on a threshold of the sum of the signal amplitude areas. Experimental surveys were conducted at construction sites: first, for setting plasterboards for two detached house construction projects and, second, for setting rebar at a large office building site. The findings of this experimental study are as follows. First, an accelerometer can be used in congested construction sites, and data can be obtained continuously. Second, this simple identification of active/inactive workers allows for the measurement of performance and the detection of problems at construction sites. Third, from the data, the hypothesis regarding workers' tendencies can be tested, that is, how workers' skill levels may affect the fluctuation of activity intensity. Therefore, in future studies, by increasing the data on workers, researchers could develop methods to improve the performance of workers.

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Major prefabricated housing manufacturers started their business in the 1960s and became world‐class large housing companies. This study clarifies the early stages of development in 9 major prefabricated housing manufacturers based on interviews with their in‐house engineers and architectural designers as well as through the analysis of related documents. Early prefabricated houses were developed intensively by a small number of engineers. Various architectural styles and specialists, including foreign architecture, famous architects and academics, affected some aspects of these developments. Furthermore, each of the early prefabricated houses had many unique building system characteristics. Some of these characteristics were modified in the early stages of development, while others still remain today.

In Okinawa, new wooden house construction starts is very small compared with in the whole Japan. So, wooden house builders in Okinawa have many difficulties, like shortage of lumbers or carpenters. But, from the 1990s, pre-cut lumber shipped from southern Kyushu area have got used in Okinawa. With this new building method, some companies which have no experience of wooden construction moved onto wooden house construction. Most of them build small numbers of wooden houses, and do another business on the other hand. And wooden house building system is influenced by limited distribution channel as well as environmental factor.

In Korea, most traditional houses were built in wooden post and beam construction. However, after WW2, wooden construction decreased, and reinforced concrete flats became common. Thus, both workers and lumber for wooden construction are in short. However, after 1990, hundreds of wooden frame houses started to be constructed per year; after 2005, even wooden post and beam houses increased. Furthermore, Korean government started wooden post and beam house development projects. This study discusses actual situations of wooden construction system in recent Korea, such as government, carpenters, lumber, among others, in particular wooden post and beam construction.