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The South Korean meteorological and environmental satellite GEO-KOMPSAT-2A (GK-2A) was launched into geostationary orbit at $128.2^{\circ}$ 128.2 ∘ East on 4 December 2018. The space weather observation aboard GK-2A is performed by the Korea Space Environment Monitor. It consists of three particle detectors, a charging monitor and a four-sensor Service Oriented Spacecraft Magnetometer (SOSMAG). The magnetometer design aims for avoiding strict magnetic cleanliness requirements for the hosting spacecraft and an automated on-board correction of the dynamic stray fields which are generated by the spacecraft. This is achieved through the use of two science grade fluxgate sensors on an approximately one meter long boom and two additional magnetoresistance sensors mounted within the spacecraft body. This paper describes the instrument design, discusses the ground calibration methods and results, presents the post-launch correction and calibration achievements based on the data which were acquired during the first year in orbit and demonstrates the in-flight performance of SOSMAG with two science cases. The dynamic stray fields from the GK-2A spacecraft, which was built without specific magnetic cleanliness considerations, are reduced up to a maximum factor of 35. The magnitude of the largest remnant field from an active spacecraft disturber is 2.0 nT. Due to a daily shadowing of the SOSMAG boom, sensor intrinsic offset oscillations with a periodicity up to 60 minutes and peak-to-peak values up to 5 nT remain in the corrected data product. The comparison of the cleaned SOSMAG data with the Tsyganenko 2004 magnetic field model and the magnetic field data from the Magnetospheric Multiscale mission demonstrates that the offset error is less than the required 5 nT for all three components and that the drift of the offsets over 10 months is less than 7 nT. Future work will include a further reduction of the remaining artefacts in the final data product with the focus on lessening the temperature driven sensor oscillations with an epoch based identification and correction.

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Cogging torque reduction measures are hardly applied to low-cost sub-fractional hp brushless direct current (BLDC) motors, because the additional fabrication operations involved typically increase both the manufacturing complexity and cost significantly. By proposing an innovative punching layout, this paper shows how to minimize the high cogging torque of the mass-produced single-phase outer-rotor BLDC claw-pole motor-opposed to conventional cogging torque reduction-with no increase to the manufacturing cost. Systematically, a way is presented in which the selected introduction of auxiliary slots can double the cogging torque fundamental frequency, making stator claw skewing much more effective in reducing the cogging torque; both measures can be included at the stage of punching the steel sheets and subsequent deep-drawing thereof, at no additional cost. A detailed analysis of the effects of the cogging torque reduction measures on the most important motor performance parameters is conducted. The findings show that, with the exception of a three percentage point reduction in the efficiency, the proposed design can reduce the peak-to-peak cogging torque by 70% in both the simulations and experiments. The reduction in the cogging torque translates into a reduction in the output torque ripple of 17%, ensuring smoother operation especially at low speeds.