Drag reduction phenomena, in which 14% drag reduction of tap water flowing in a 16 mm-diameter pipe occurs in the laminar flow range, have been clarified. Experiments were carried out to measure the pressure drop and the velocity profile of tap water and an aqueous solution of glycerin flowing in pipes with highly water-repellent walls, by using a pressure transducer and a hot-film anemometer, respectively. The same drag reduction phenomena also occurred in degassed tap water when using a vacuum tank. The velocity profile measured in this experiment gives the slip velocity at the pipe wall, and it was shown that the shear stress is directly proportional to the slip velocity.The friction factor formula for a pipe with fluid slip at the wall has been obtained analytically from the exact solution of the Navier–Stokes equation, and it agrees well qualitatively with the experimental data.The main reasons for the fluid slip are that the molecular attraction between the liquid and the solid surface is reduced because the free surface energy of the solid is very low and the contact area of the liquid is decreased compared with a conventional smooth surface because the solid surface has many fine grooves. Liquid cannot flow into the fine grooves owing to surface tension. These concepts are supported by the experimental result that drag reduction does not occur in the case of surfactant solutions.

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This study aims to determine the effect of job satisfaction on employee performance with job stress as a mediating variable. The subjects used in this study were employees at PT. XYZ. PT. XYZ is a multinational real estate company. The number of samples taken in this study were 75 respondents. The data obtained was carried out from the results of distributing questionnaires through google form using purposive sampling technique. Processing of the collected data is carried out with the SmartPLS program. Based on the results of data analysis, it can be concluded that job satisfaction has a significant negative effect on job stress, and job stress has a significant negative effect on employee performance. Also, job satisfaction has no effect on employee performance. However, job stress can mediate the effect of job satisfaction on employee performance. This research shows that in order to improve employee performance, companies need to pay attention to employee job satisfaction in order to reduce employee work stress levels. Penelitian ini bertujuan untuk mengetahui pengaruh Kepuasan Kerja terhadap Kinerja Karyawan dengan Stres Kerja sebagai variabel mediasi. Subjek yang digunakan dalam penelitian ini adalah karyawan pada PT. XYZ. PT. XYZ merupakan perusahaan di bidang real estate berskala multinasional. Jumlah sampel yang diambil dalam penelitian ini sebanyak 75 responden. Data yang diperoleh dilakukan dari hasil penyebaran kuesioner melalui google form dengan menggunakan teknik pengambilan sampel purposive sampling. Pengolahan data yang telah terkumpul dilakukan dengan program SmartPLS. Berdasarkan hasil analisis data, maka dapat disimpulkan bahwa Kepuasan Kerja berpengaruh negatif signifikan terhadap Stres Kerja, dan Stres Kerja berpengaruh negatif signifikan terhadap Kinerja Karyawan. Serta, Kepuasan Kerja tidak berpengaruh terhadap Kinerja Karyawan. Akan tetapi, Stres Kerja dapat memediasi pengaruh Kepuasan Kerja terhadap Kinerja Karyawan. Dari penelitian ini menunjukkan bahwa untuk dapat meningkatkan Kinerja Karyawan, perusahaan perlu memperhatikan Kepuasan Kerja karyawan agar dapat menurunkan tingkat Stres Kerja karyawan.

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