목적: 본 연구에서는 VR(Virtual Reality)기기의 사용이 양안시기능에 미치는 영향에 대해 알아 보고자 하였다. 방법: 본 연구는 양안시기능 이상 및 안질환이 없고, 교정시력이 0.8 이상인 남·여(22.3±1.53 세) 20명을 대상으로 하여 VR기기(Virtual Reality, Samsung:Sm-r325, Korea) 사용 전후 시기능의 변화를 비교 분석하였다. 시기능검사는 자동굴절검안기(Huvitz HRK-8000A Korea)를 통한 굴절이상도, 단안조절근점, 폭주근점, 입체시(Titmus Fly)검사, 근거리 사위도(수정된 토링톤 법)를 측정하였다. 1차 시기능검사 후 30분 동안 VR기기를 사용 하도록 한 후, 검사를 재실시 하여 전과 후의 시기능 변화를 평가하였다. 결과: 굴절이상도는 VR기기 사용 전 등가구면굴절력 S-0.689D에서 사용 후 등가구면굴절력 S-0.754D로 S–0.065D 근시화 변화를 보였고, 조절근점은 VR 사용 전 9.66±2.41cm, VR 사 용 후 11.4±2.57cm로 1.74cm 증가하였으며 폭주근점은 8.56±1.88cm에서 10.03±2.29cm로 1.47cm 증가하였다. 입체시는 79±45.53sec에서 103.5±59.76sec로 24.5sec 차이의 변화를 보였고 근거리 사위도는 4.50±6.48△ 외사위에서 6.40±6.56△ 외사위로 1.90△ 변화량을 보 였다. 결론: 이상의 결과에 따라, VR(Virtual Reality) 기기 사용 후 근시도는 근시방향으로 증가하고, 조절근점과 폭주근점은 거리가 증가하여 조절력과 폭주력이 감소함을 알 수 있었다. 그리고 입체시는 VR 기기 사용 후 감소하고, 근거리 사위도는 외사위 방향으로 증가하였다. 따라서 VR 을 사용한 직 후 굴절검사나 양안시 검사 결과는 변화가 있을 수 있기 때문에 장시간의 VR 사용은 자제하고 적절한 휴식을 취하는 것이 좋을 것으로 사료된다.

The problem of disposal of brine due to increased MD/RO desalination plant has recently become a big social issue. The chlor-alkali process through electrolysis of brine has been studied as a method to overcome this problem. In order to increase the electrolysis efficiency, a pretreatment process for removal of hard substances must be preceded. In this study, we investigated the mechanism of removal of hardness through chemical precipitation. As a result, Ca was greatly influenced by addition of Na2CO3, and Mg was strongly influenced by pH. Also, the addition of NaOH and Na2CO3 enabled simultaneous removal of Ca and Mg, and showed a removal efficiency of 99.9% or more. Finally, the residual concentrations of Ca and Mg in the brine after the reaction were 0.14 and 0.13 mg/L, respectively. Saturation index was calculated using Visual MINTEQ 3.1, and solid phase analysis of the precipitate was performed by FE-SEM and PXRD analysis. It was confirmed that precipitate formed by the formation of calcite and brucite.

The objective of this study is to analyze the investment adequacy of the projects implemented according to the master plan on sewerage rehabilitation at Seoul. The planned and actually implemented ratio of invested money on sewage treatment plants (STPs) to sewers were compared in two temporal periods. Though the planned ratio of investment on STPs to sewers was 50:50 (in 2009-2020) , the actual implemented ratio in 2009-2013 was 34:66. Until 2020, the greater investment ratio on STPs to sewers should be made considering the necessity of coping with stricter legal compliance on advanced treatment, stormwater treatment and so on. The priority of the planned and partially implemented projects among four STPs and at each STP was evaluated. Considering only the performance indicator of reduced load of BOD, T-N, T-P per the capacity of each STP facility, the performance among four STPs was shown as Jung-Rang>Tan-Cheon>Seo-Nam>Nan-Ji. The reverse order of the performance results in the past may be considered for future investment priority, but the efficiency of operation implemented at each STP, deteriorated status of each STP, investment in the past and so forth should also be considered. As for the priority of projects conducted within each STP, projects related to legal compliance (such as advanced tertiary treatment, stormwater treatment, etc.) have highest priority. Odor-related project and inhabitant-friendly facility related projects (such as building park on STPs, etc.) has lower priority than water quality related projects but interactivity with end-users of sewerage should also be important.

As sewerage systems have obsolete, as quality and service level standards increase, and as rain characteristics change, the sewerage utility authorities are challenged to develop cost recovery strategies that assure financial sustainability. In this study, we conducted scenario analysis to examine the effect of three alternatives of partial or full sewerage cost recovery in Seoul during 2014-30 periods. It turned out that the alternative 1 is optimal and recommended. According to alternative 1, we had better increase annually sewerage fee by 14.8% until 2020 and thereafter apply only the inflation rate in setting sewerage fee. It would gradually decrease the deficit after 2019. The accumulated deficit of 13 billion Won in 2030 was estimated.We expect that this kind of analysis may provide useful informations to help sewage utility staffs, decision makers, and regulatory authorities understand, develop and implement ultimate full cost recovery strategy for many municipalities.

As sewer flooding frequents due to localized and concentrated stormwater and increased non-permeable surface area after urbanization, building cities with sound water recycle and accordingly efficient management of rainwater is demanded. To do this, the existing sewage (including rainwater) fee imposition system should be philosophically evaluated. This study presents problematic issues of the existing domestic sewage fee imposition system considering the principle of sharing costs on the service of sewage and rainwater collection and treatment. Four methods to improve the existing sewage fee imposition system are suggested: 1) imposing stormwater fee according to Polluter Pays Principle, 2) clarification of the share of public sector, 3) reducing or exempting the sewerage fee for inhabitants reducing urban runoff by constructing their own rainwater management facilities, 4) imposing charge for discharging rainwater to sewers due to new development action. Short, mid, or long term planning for rainwater management is recommended considering the situation of each municipality.

C. obtusa, an essential oil produced in Jeollanamdo Gangjin, is the most effective plant oil for easing Sick House Syndrome, having an effect similar to a therapeutic walk in the woods and acting as a sterilizer. In light of its medicinal importance, its composition, antibacterial activity and ability to mitigate an offensive odor have been analyzed. Through GC-MS, I confirmed that it contains approximately 50 components, 80.30% of which are various monoterpenes. It was effective at alleviating malodors from formaldehyde, ammonia, trimetylamine and methylmercaptan as determined in colorimetric gas detection tube tests in comparison with lemongrass and clove leaf essential oil. I obtained from Minimal Inhibition Concentration(MIC) of C. obtusa, higher concentrations will lead to increased antibacterial activity. Therefore it is estimated that utility value of it will be grow more and more.

Hydroxyapatite (HAp) and biphasic calcium phosphate (BCP) nano powders were synthesized using the microwave-assisted synthesis process dependent on pH and microwave irradiation time. The average size of a powder was less than 100 nm in diameter. Through in-vitro cytotoxicity tests by an extract dilution method, the HAp and BCP nano powders have shown to be cytocompatible for L-929 fibroblast cells, osteoblastlike MG-63 cells and osteoclast-like Raw 264.7 cells. The activation of osteoblast was estimated by alkaline phosphatase (ALP) activity. When the HAp and BCP were treated to MG-63 cells, alkaline phosphatase activities increased on day 3, compared with those of the untreated cells. Also, the collagen fibers increased when the HAp and BCP powders suspension were treated to MG-63 cells, compared to those of the untreated cells. Quantitative alizarin red S mineralization assays showed a trend toward increasing mineralization in osteoblast cultured with powder suspension. In conclusion, hydroxyapatite and biphasic calcium phosphate appeared to be a bone graft substitute material with optimal biocompatibility and could be further applied to clinical use as an artificial bone graft substitute.