Active Galactic Nuclei (AGN) with bright radio jets oer the opportunity to study the structure of and physical conditions in relativistic out ows. For such studies, multi-frequency polarimetric very long baseline interferometric (VLBI) observations are important as they directly probe particle densities, magnetic eld geometries, and several other parameters. We present results from rst-epoch data obtained by the Korean VLBI Network (KVN) within the frame of the Plasma Physics of Active Galactic Nuclei (PAGaN) project. We observed seven radio-bright nearby AGN at frequencies of 22, 43, 86, and 129 GHz in dual polarization mode. Our observations constrain apparent brightness temperatures of jet components and radio cores in our sample to > 108:01 K and > 109:86 K, respectively. Degrees of linear polarization mL are relatively low overall: less than 10%. This indicates suppression of polarization by strong turbulence in the jets. We found an exceptionally high degree of polarization in a jet component of BL Lac at 43 GHz, with mL  40%. Assuming a transverse shock front propagating downstream along the jet, the shock front being almost parallel to the line of sight can explain the high degree of polarization.

Abstract
1. INTRODUCTION
2. OBSERVATIONS AND ANALYSIS
    2.1. Observations and Data Reduction
    2.2. Data Analysis
3. RESULTS
    3.1. 3C 111
    3.2. 3C 120
    3.3. 3C 84
    3.4. 4C +01.28
    3.5. BL Lac
    3.6. DA 55
4. DISCUSSION
    4.1. Brightness Temperature Distributions
    4.2. Correlations between Parameters
    4.3. Plasma Opacity and Degree of Polarization
5. SUMMARY
REFERENCES

• Jae-Young Kim(Department of Physics and Astronomy, Seoul National University/Max-Planck Institut fur Radioastronomie)
• Sascha Trippe(Department of Physics and Astronomy, Seoul National University) Corresponding author
• Bong Won Sohn(Korea Astronomy and Space Science Institute)
• Junghwan Oh(Department of Physics and Astronomy, Seoul National University)
• Jong-Ho Park(Department of Physics and Astronomy, Seoul National University)
• Sang-Sung Lee(Korea Astronomy and Space Science Institute)
• Taeseok Lee(Department of Physics and Astronomy, Seoul National University)
• Daewon Kim(Department of Physics and Astronomy, Seoul National University)