Surface plasmon resonance is the resonant oscillation of conduction electrons at the interface between negative and positive permittivity material stimulated by incident light. In particular, when light transmits through the metallic microhole structures, it shows an increased intensity of light. Thus, it is used to increase the efficiency of devices such as LEDs, solar cells, and sensors. There are various methods to make micro-hole structures. In this experiment, micro holes are formed using a wet chemical etching method, which is inexpensive and can be mass processed. The shape of the holes depends on crystal facets, temperature, the concentration of the etchant solution, and etching time. We select a GaAs(100) single crystal wafer in this experiment and satisfactory results are obtained under the ratio of etchant solution with H2SO4:H2O2:H2O = 1:5:5. The morphology of micro holes according to the temperature and time is observed using field emission - scanning electron microscopy (FE-SEM). The etching mechanism at the corners and sidewalls is explained through the configuration of atoms.

Phosphorus (P) is a limited, essential, and irreplaceable nutrient for the biological activity of all the living organisms. Sewage sludge ash (SSA) is one of the most important secondary P resources due to its high P content. The SSA has been intensively investigated to recover P by wet chemicals (acid or alkali). Even though H2SO4 was mainly used to extract P because of its low cost and accessibility, the formation of CaSO4 (gypsum) hinders its use. Heavy metals in the SSA also cause a significant problem in P recovery since fertilizer needs to meet government standards for human health. Therefore, P recovery process with selective heavy metal removal needs to be developed. In this paper some of the most advanced P recovery processes have been introduced and discussed their technical characteristics. The results showed that further research is needed to identify the chemical mechanisms of P transformation in the recovery process and to increase P recovery efficiency and the yields.

Cobalt coated tungsten carbide-cobalt composite powder has been prepared through wet chemical reductionmethod. The cobalt sulfate solution was converted to the cobalt chloride then the cobalt hydroxide. The tungsten carbidepowders were added in to the cobalt hydroxide, the cobalt hydroxide was reduced and coated over tungsten carbidepowder using hypo-phosphorous acid. Both the cobalt and the tungsten carbide phase peaks were evident in the tungstencarbide-cobalt composite powder by X-ray diffraction. The average particle size measured via scanning electron micro-scope, particle size analysis was around 380 nm and the thickness of coated cobalt was determined to be 30~40 nm bytransmission electron microscopy.

Spherical nanosized cobalt powder with an average size of 150-400 nm was successfully prepared at room temperature from cobalt sulfate heptahydrate (). Wet chemical reduction method was adopted to synthesize nano cobalt powder and hypophosphorous acid () was used as reduction agent. Both the HCP and the FCC Co phase were developed while concentration ranged from 0.7 M to 1.1 M. Secondary phase such as and were also observed. Peaks for the crystalline Co phase having HCP and FCC structure crystallized as increasing the concentration of , indicating that the amount of reduction agent was enough to reduce . Consequently, a homogeneous Co phase could be developed without second phase when the ratio exceeded 7.

In this study, the pure iron powder was treated with aqueous phosphoric acid to produce phosphate insulating layer on the surface. After drying the powder, it was compacted in a mold with a diameter of 20mm at 800MPa. The powder compacts were then heat treated at for 1 hour. The results showed that insulated iron powder was obtained with uniform phosphate layer by chemical reaction. With increased amount of phosphate layer, the core loss and density of compacts were decreased. It was also found that the addition of ethyl alcohol during insulating reaction resulted in improved core loss value.

Ag powder was prepared from by wet chemical reduction method using various reduction agent system involving , (AgCl) and Ag complex ion aqueous solution. The pure Ag powder could be prepared regardless of reaction system but the particle shape and distribution were affected very much according to the kind of reduction agents and reaction systems. The optimum reaction system for the preparation of the silver powder having the uniform particle shape and size distribution was Ag complex ion aqueous solution-reduction agent system and in particular, and as a reduction agent leaded the more uniform particle shape and size distribution

보리입모중 벼 파종에 있어서 보리짚 시용에 따른 경운방법과 질소시용량별 관개수중에 용출된 각 성분함량 변화를 검토하였던 바, 그 결과를 요약하면 다음과 같다. 1. pH는 무경운재배에서는 시비수준간 차리가 없었으나 경운재배에서는 컸으며, 10일까지는 시비수준이 높을수록 pH가 높았으나 그 이후는 비슷하였다. 2. EC는 무경운에 비해 경운재배에서 높았으며, 경운의 유 ㆍ무에 관계없이 시비수준이 높을수록 EC도 높았다. 시기별로 보면 10일에 최고수준에 도달하였다가 그 후 감소경향이나, 20일에는 초기와는 달리 시비수준이 높을수록 EC가 감소하였고, 그 감소폭은 경운재배에서 컸다. 3. 용존산소는 무경운에 비해 경운에서 높았으며, 시비량이 많을수록 낮은 경향을 보였다. 경운방법별로는 무경운에서는 시용후일수가 경과됨에 따라 다소 증가하는 경향이었으며, 무처리에 비해 매우 낮았으나, 경운재배에서는 초기에 매우 높고 10일에 급격히 감소하였으며 그 후 다시 증가하였다. 4. NH4 -N는 경운의 유 ㆍ무에 관계없이 시비수준이 높을수록 높았으나, 20일에는 시비량간 차이는 없었다. 경운방법간에는 무경운에서는 10일까지 높고 그 후 감소를 보였으나 경운에서는 초기(5일)에 매우 높았다가 급격히 감소하였고, 15일에 다시 감소하였으나 20일에는 거의 발현되지 않았다. NO3 -N는 무경운에서는 처리일수 및 시비수준간의 차이가 매우 컸으며, 10일에 최고수준을 보였고, 그 후 20일까지 급격히 감소하였다. 경운구에서는 처리일수가 경과함에 따라 감소경향을 보였으나, 시비수준간 차이는 보이지 않았다. 5. PO4 3- 은 경운재배에 비해 무경운재배에서 높았으며, 두처리 모두 시비수준이 높을수록 높았으나, 무경운재배에 비하여 경운재배에서는 시일의 경과에 따라서도 차이가 크지 않았고 함량도 낮았다. 6. 양이온함량은 모두 경운 유 ㆍ무에 관계없이 시비수준이 높을수록 높은 경향을 보였고, 10일에 최고수준을 보인 후 완만한 감소를 나타냈으며, K+, Ca2+에 비해 Mg2+이 보다 낮은 함량을 보였다.