Associate Professor

Laboratory Address

1-1 Gakuen-Kibanadai-Nishi, Miyazaki City, Miyazaki Prefecture, 889-2192 JAPAN

Research Fields, Keywords

Forest Engineering, Forest Operation, Forest Road

Mail Address

E-mail address

Laboratory Phone number


Graduating School 【 display / non-display


    The University of Tokyo   Faculty of Agriculture   Graduated

Graduate School 【 display / non-display


    The University of Tokyo    Doctor's Course  Completed

Field of expertise (Grants-in-aid for Scientific Research classification) 【 display / non-display

  • Forest science


Research Career 【 display / non-display

  • Studies about mechanized harvesting system in forestry

    (not selected)  

    Project Year: 1995.04  -   

Papers 【 display / non-display

  • Forest road planning using precision geographic data under climate change

    Mika YOSHIDA, Rin SAKURAI and Hideo SAKAI

    International Journal of Forest Engineering     2018.08  [Refereed]

    Joint Work

     View Summary

    Frequent heavy rainfall is suspected to cause failures on spur roads especially those constructed by earthworks . It is essential to construct robust, cost-efficient and well-maintained road networks to react to uncertain events. Laser imaging detection and ranging technology (LiDAR) can measure the topography. By constructing spur roads based on the watercourse map estimated from the digital elevation model taken by LiDAR, the change of watercourses could be followed by using LiDAR after construction and spur road failures were surveyed to evaluate the road planning process. The route was selected to avoid watercourses using stable points such as natural bench. The roads crossing the watercourses were protected from surface runoff by dispersal drainage systems. The route and dispersal drainage systems effectively prevented runoff from soil erosion from a cut slope. The height of the cut slope and the stability of the natural slope were key for routing and selecting drainage systems. Spur roads with functional dispersal drainage systems at appropriate places are expected to improve the ability of water conservation in mountainous forests, which could contribute to keeping them as the “green infrastructure” and adapting to climate change.


  • Productivity of loaders and forwarders in Japanese forestry operation conditions

    Simon Berg, Mika Yoshida, Rin Sakurai and Hideo Sakai

    Journal of Forest Research   23   149 - 155   2018.05  [Refereed]

    Joint Work

     View Summary

    The harvesting costs in Japan need to be reduced to increase the wood supply. Detailed information about machine productivity facilitates the identification of the most cost-effective machines. Therefore, an IWAFUJI GS-65LJV grapple (GS65), two IWAFUJI GS-90LJV grapples (GS90), an IHI F801 forwarder (F801) and a Morooka MST800VDL forwarder (MST800) were studied at a thinning (site 1). A GS90, a KETO 150 Eco processor (KETO150) and a Morooka MST1500VDL forwarder (MST1500) were also studied in a clear-cutting (site 2). The difference between the GS65’s and the GS90’s unloading time at site 1 was insignificant. The GS65’s loading time was significantly faster than the GS90’s loading time at site 1, but the conditions were different. It is, therefore, likely that the GS65 is preferable to use as it is less expensive. The loaded assortment decided whether the GS90 or the KETO150 was more productive at site 2. The GS90 is preferable to use as it is less expensive. The F801 was faster than the MST800 and MST1500 and is, therefore, more productive except on short forwarding distances as it is slightly more time-consuming to load. Larger Japanese forwarders and grapple loaders like the GS65, GS90, F801, MST800 and MST1500 seemed to be more productive than smaller forwarders and grapple loaders.


  • Comparison of productivity and cost depending on slope when forwarding short length logs with small Japanese forwarders

    Simon Berg, Mika Yoshida, Rin Sakurai, Hideo Sakai

    International Journal of Forest Engineering   28   176 - 185   2017.11  [Refereed]

    Joint Work

     View Summary

    Demand for forest biomass is growing in Japan, which makes cost-effective harvesting operations important. Information about the cost and productivity of machines helps in selecting the most cost-effective machines. However, there are some limitations in the available information about forwarders with > 3 t load capacity in Japanese conditions. An IHI F801 (F801) and an IWAFUJI U-5CG (U5) forwarder were investigated in a thinning with 0–73% slope. The F801 was found to have significantly higher speed than the U5, but no significant difference was found for loading and unloading time. The speed decreased slightly with increased slope, this decrease was more evident for the U5 than for the F801. Loading and unloading time (s/log) decreased with increasing number of logs per crane cycle. Time consumption per m3 was 25–32% higher for the U5 than for the F801. However, the cost per hour was about 31–32% higher for the F801 than for the U5, resulting in a cost per m3 that was 1.9–5.8% lower for the U5. This situation indicates that the U5 is more cost-effective than the F801, in Japanese conditions. It also seems that larger self-loading forwarders like the F801 and U5 are more cost-effective than smaller forwarders and forwarders loaded with loaders. However, the F801 could become more cost-effective than the U5 if changes in salary cost, scheduled hours, maintenance rate, and/or utilization rate occur. These facts are particularly important to consider if the F801 would be used overseas.


  • The difference of operational efficiency by the precise stocking

    Sakurai, R., Oka, M., Tanabe, K.

    Kyushu Journal of Forest Research   70   113 - 116   2017.03  [Refereed]

    Joint Work

  • Evaluation of Chipping Productivity with Five Different Mobile Chippers at Different Forest Sites by a Stochastic Model

    Mika YOSHIDA, Simon BERG, Rin SAKURAI, and Hideo SAKAI

    Croatian Journal of Forest Engineering   37   309 - 318   2016.06  [Refereed]

    Joint Work

     View Summary

    It is important to evaluate chipping productivity that often differed according to the timing of observations and varied unexpectedly. A variation in production was the major concern of stakeholders for sustainable forest operation to establish regularly attainable production sched- ules on many operational levels. The aim of this study was to estimate the variance of chipping productivity by using a stochastic simulation model to achieve the objective evaluation of chipper performances. Chipping operations of five different kinds of mobile chippers, i.e. three smaller and two middle and larger ones in horse powers, were investigated. Probability dis- tributions of material size and feeding time for chipping in a log-normal distribution were estimated. The estimates were made based on chipping operations performed 2000 or 4000 times by mechanical repetitions. Except for the largest chipper, whose observed productivity was 338 loose m#U3#UR /hr, all of the observed productivities, varying from 18 to 68 loose m#U3#UR/hr, were located within a two-sided confidential interval whose difference between both ends was 4 to 10 loose #U3#UR/hr. The estimates were, generally, reliable with small variances around the median productivity values in the model. By this stochastic model, chipper productivity could be shown objectively, while the accuracy would be improved more by increasing sample size and accurate material size measurement. It was elucidated that the operations followed by chipping should encompass enough volume capacity to provide stable chipping productivity.

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Presentations 【 display / non-display

  • Can forestry machines be heritages?

    SAKURAI, Rin

    129th Annual JFS Meeting  (Kochi Pref., JAPAN)  2018.03  -  2018.03  The Japanese Forest Society

     View Summary

    In "Japanese Forestry Heritage" by Japanese Forestry Society, forestry railway, and traditional harvesting system are nominated from forestry machines. The possibility about nomination about recent forestry machines will be discussed.

  • An analysis of infrastructure for transporting biomass in Miyazaki prefecture.


    The 128th Annual Japan Forest Society meeting  (Kagoshima City, Kagoshima Pref.)  2017.03  -  2017.03  The Japan Forest Society

  • The quantitative evaluation of environmental conservation including root system of forest road


    The 2nd International Symposium on Tropical Forest Ecosystem Science and Management  2013.09  -  2013.09  Tropical Forest Ecosystem Sciences Research Center, Faculty of Agriculture and Food Sciences Universiti Putra Malaysia Bintulu Sarawak