Biomechanical Classification of Judo Throwing Techniques (Nage Waza)

In this paper it is applied the classic mechanical point of view to classify all the movements known as throwing judo techniques; the application of the Newtonian physical methods and principles is able to rationalize the whole matter and to group under only two very simple and clear principles all the movements, before grouped in many generic and not very clear way.Comment: 11 pages, 14 Figures, 3 Tables, Presented at fifth International Symposium on Biomechanics in Sport Athens 198

The British Ju-jitsu Society and the influence of Kodokan Judo on early jujutsu in the U.K.

© 2023 The Author(s). This is an open access article under the Creative Commons Attribution-NonCommercial-NoDerivatives CC BY-NC-ND licence, https://creativecommons.org/licenses/by-nc-nd/4.0/In the United Kingdom (U.K.) in the late Victorian and early Edwardian eras there was an explosion in the popularity of the Japanese martial art jujutsu, with seemingly invincible Japanese exponents touring and taking on all comers in the music halls. As this early wave of popularity subsided a number of organisations were established to continue the practice of jujutsu, and other Japanese martial arts. Most notable of these was The Budokwai in London, established in 1918 by Gunji Koizumi, which from 1920 would become one of the foremost judo clubs in the West. Recent discoveries shed light on another organisation from this era called the British Ju-jitsu Society (BJS). Established in 1926, the BJS co-existed with The Budokwai and had member clubs throughout the U.K. Here, we provide an overview of the BJS, its activity, and insights into its operation and legacy.Peer reviewe

Penjadwalan Produksi Job shop Mesin Majemuk Menggunakan Algoritma Non Delay untuk Meminimalkan Makespan

Scheduling is an important factor in both manufacturing and service industry environments. Scheduling is a resource allocation arrangement for completing tasks that involve work, resources and time. With the scheduling, all work can be completed according to priority and can minimize processing time, so that makespan is minimal. In addition, it can reduce idle machines and reduce the inventory of semi-finished goods. Maryati Small Micro and Medium Enterprises (IKM) is a business that is engaged in the manufacture of clothing that produces various types of products such as baby clothes, teenage clothes to adults. So far, IKM Maryati is in the process of machine scheduling by determining the order of Job execution based on the longest to shortest total Job processing time. Scheduling with this method creates problems for the company, as evidenced by the accumulation of semi-finished goods at several work-stations. Another problem is when orders arrive at a certain period with a large variety and number of products, causing Job completion that exceeds the target time (due-date). The size of the makespan causes the production time to increase, so the company is late to start production of orders in the following month. In this study, the Non-delay algorithm is used to solve the problems that arise in IKM Maryati. The result obtained is the scheduling using the existing method by IKM Maryati which produces 44 days makespan value. Meanwhile, by applying the Non-delay compound engine algorithm, it produces a makespan of 42 days. This shows that the compound machine Non-delay Algorithm method can minimize the makespan value in IKM Maryati. There is an efficiency of 4.55% in both time and cost variables.  Penjadwalan merupakan faktor penting pada lingkungan industri manufaktur maupun jasa. Penjadwalan merupakan pengaturan alokasi sumber daya untuk menyelesaikan tugas-tugas yang melibatkan pekerjaan, sumber daya dan waktu. Dengan adanya penjadwalan, semua pekerjaan dapat diselesaikan sesuai dengan prioritasnya dan dapat meminimalkan waktu pengerjaan, sehingga makespan menjadi minimal. Selain itu, juga dapat mengurangi mesin-mesin yang menganggur dan dapat mengurangi persediaan barang setengah jadi. Industri Kecil dan Menengah (IKM) Maryati merupakan bidang usaha yang bergerak dibidang pembuatan pakaian yang memproduksi berbagai jenis produk seperti pakaian bayi, pakaian remaja hingga dewasa.  Selama ini IKM Maryati dalam proses penjadwalan mesin dengan cara menentukan urutan pengerjaan Job berdasarkan total waktu pengerjaan Job terlama hingga terpendek. Penjadwalan dengan metode tersebut menimbulkan masalah bagi perusahaan, dibuktikan dengan adanya penumpukan barang setengah jadi di beberapa stasiun kerja. Masalah lain adalah ketika pesanan yang datang pada suatu periode tertentu dengan variasi dan jumlah produk yang banyak sehingga menimbulkan penyelesaian Job yang melebihi waktu target (due-date). Besarnya makespan menyebabkan waktu produksi menjadi bertambah, sehingga perusahaan terlambat untuk memulai produksi pesanan pada bulan selanjutnya. Pada penelitian ini, algoritma Non – delay digunakan untuk menyelesaikan permasalahan yang muncul di IKM Maryati. Hasil yang diperoleh adalah penjadwalan dengan metode yang selama ini digunakan IKM Maryati menghasilkan nilai makespan 44 hari. Sedangkan, dengan menerapkan algoritma Non-delay mesin majemuk menghasilkan makespan 42 hari. Hal ini menunjukkan bahwa metode Algoritma Non-delay mesin majemuk dapat meminimasi nilai makespan di IKM Maryati. Terdapat efisiensi sebesar 4.55% baik pada variabel waktu maupun variabel biaya

Infrared thermography-calorimetric quantitation of energy expenditure in biomechanically different types of jūdō throwing techniques: a pilot study

It was the purpose of this pilot study to assess the energy expenditure (EE) of two biome-chanically different jūdō throws, namely, the simple mechanical couple-based uchi-mata vs. the lever-based throw ippon-seoi-nage, using infrared thermal calorimetry (ITC). Testing subjects included one Caucasian female elite athlete (age: 26.4 years) and one male veteran jūdōka (age: 50.8 years). ITC images were captured by an Avio NEC InfRec R300 camera and thermal data obtained were plotted into a proprietary equation for estimation of EE. Data were compared to respiratory data obtained by a Cosmed K4 b2 portable gas analyzer. Oxy-gen consumption as estimated by ITC capture during practice of uchi-mata was markedly lower than during performance ippon-seoi-nage in the female (457 mL•min-1 vs. 540 mL•min-1, P<0.05) and male subject (1,078 mL•min-1 vs. 1,088 mL•min-1, NS), with the difference in values between both genders subject being significant (P<0.01). The metabolic cost of the exercise (uchi-mata vs. ippon-seoi-nage) itself was 1.26 kcal•min-1 (88 W) vs. 1.68 kcal•min-1 (117 W) (P<0.05) in the female subject, and 2.97 kcal•min-1 (207 W) (P<0.01) vs. 3.02 kcal•min-1 (211 W) (NS) in the male subject. Values for the female were significantly differ-ent (P<0.01) from those of the male subject. The results support the initial hypothesis that the couple-based jūdō throws (in this case, uchi-mata) are energetically more efficient than lever-based throws, such as ippon-seoi-nage. Application of this approach may be of practical use for coaches in optimizing energy-saving strategies in both elite and veteran jūdō athletes