• Journal of Korea Game Society
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• v.13 no.2
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• pp.5-16
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• 2013

The purpose of this study is how to occur the temporality in Digital Gameplay. There is two types of time in Gameplay. One is Irreversibility time that goes passed through a game world like a chronology order. Another is Reversibility time that returns and renews the time. The time's duality is caused by player's intervene and experience. And the polychronic temporality in gameplay makes the rhythm as replay and eternal cyclic time.

• Journal of Periodontal and Implant Science
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• v.35 no.2
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• pp.475-490
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• 2005

본 실험은 흡연이 치주인대세포의 기능에 미치는 영향을 알아보기 위해 담배 부산물 중 하나인 니코틴이 지주인대세포의 부착과 성장 및 세포의 가역성에 미치는 영향을 관찰하였다. 니코틴이 치주인대세포의 부착에 미치는 영향을 관찰하기 위하여 치주인대세포에 니코틴을 투여한 후 1, 3, 6, 12, 24시간째 trypan blue 염색 후 부착된 세포수의 측정과 H&E stain후 형태학적 관찰을 하였고 니코틴이 치주인대세포의 성장에 미치는 영향을 관찰하기 위하여 치주인대세포에 니코틴을 투여한 후 1, 4, 7, 11, 14일째 trypan blue 염색 후 증식된 세포수의 측정과 H&E stain후 형태학적 관찰을 하였다. 또 니코틴의 세포독성효과의 가역성 평가를 위하여 니코틴을 투여하고 1, 4, 7, 11일째 니코틴이 없는 새로운 배지로 갈아주어 2일 더 배양한 후 trypan blue로 염색하여 세포수를 측정, 비교하였고 H&E 염색 후 형태학적 관찰을 하였다. 실험결과 니코틴 농도가 증가함에 따라 치주인대세포의 부착율은 감소되었고 24시간 배양 후 2mg/ml, 0.5mg/ml, 0.1mg/ml니코틴 투여군에서 통계학적으로 유의성 있는 부착억제가 관찰되었고(P<0.01) 형태학적 관찰결과 2mg/ml, 0.5mg/ml 니코틴 투여군에서는 대조해서 관찰되는 세포질의 확장이 관찰되지 않았다. 니코틴이 치주인대세포의 증식에 미치는 효과를 살펴본 결과 2mg/ml, 0.5mg/ml, 0.1mg/ml 니코틴 투여군에서 증식억제가 관찰되었고(P<0.01) 0.005mg/ml이하의 니코틴 투여군에서는 아무런 변화도 관찰되지 않았다. 14일 배양 후 형태학적 관찰결과 0.1mg/ml 니코틴 투여군에서 세포질내 공포를 관찰할 수 있었고 2mg/ml, 0.5mg/ml 니코틴 투여군에서는 세포의 괴사가 나타났다. 니코틴의 세포독성효과의 가역성평가결과 2mg/ml이상의 니코틴은 세포에 비가역적인 손상을 일으키며 0.5mg/ml, 0.1mg/ml 니코틴에 의한 세포독성은 초기에는 가역적이나 장기간 세포에 노출시키면 비가역적인 손상을 야기하는 것으로 나타났다.(P<0.05) 본 실험결과 담배의 구성성분 중 니코틴은 농도 의존적으로 치주인대세포의 부착과 증식에 영향을 주었고 니코틴의 치주인대세포에 대한 독성효과는 농도가 증가할수록, 시간이 지닐수록 비가역적으로 나타났다. 따라서 흡연은 치주조직재생에 영향을 미칠 것으로 생각되며 흡연의 기간과 정도가 치주질환의 심도 및 치주치료 후 불량한 치유반응과 관계가 있을 것으로 사료된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1178-1182
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• 2004

시계열 자료의 분석과 예측은 수문학분야에서 매우 중요하면, 최근 들어 특정한 수문시계열에서 카오스 특성이 발견되고 있다. 카오스 특성을 갖는 수문시계열의 예측에 있어, 기존의 거의 모든 연구는 시스템의 특성을 파악한 뒤 예측을 실시하는 표준접근법이 채택되어왔다. 그러나 Phoon 등은 시스템의 특성분석에 앞서 예측을 실시하고, 상태공 매개변수가 시스템의 특성분석단계가 아닌 예측단계에서 평가되는 가역접근법을 제안하였다. 본 연구에서는 Phoon 등이 제안한 가역접근법과 기존에 널리 적용되어온 표준접근법을 실제 일유출량 자료에 적용함으로써, 가역접근법의 적용성을 검토하고 카오스 시계열의 특성을 파악하였다. 본 연구에서 사용한 비선형 예측 기법으로는 카오스이론이 적용된 부분근사화 기법을 이용하였다. 카오스 특성분석을 통해, Bear 강 일유출량 시계열 자료에서 카오스 특성이 나타남을 알 수 있었다. 표준접근법과 가역접근법을 이용하여 Bear 강의 일유출량 자료에 대하여 예측을 실시한 결과, 카오스 특성을 갖는 일유출량 시계열 자료의 단기 예측의 우수성을 알 수 있었으면, 가역접근법이 표준접근법에 비해 좋은 결과를 나타내었다. 특히, 가역접근법은 예측단계에서 예측시간(T)에 대하여 예측매개변수를 최적화시킴으로써 보다 정밀한 예측을 할 수 있었으며, 시스템에 대한 정보손실이 발생하였을 경우 예측에 대한 상태공간 매개변수를 다시 추정해야 하는 표준접근법에 비해 실제적 적용성이 매우 우수하였다.

• The Korean Journal of Nuclear Medicine
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• v.32 no.6
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• pp.497-508
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• 1998

Purpose: Using rest T1-201/dipyridamole stress gated Tc-99m-MIBI/ 24 hour delay T1-201 SPECT, we investigated the predictive values of the markers of the stress-rest reversibility (Rev), T1-201 rest perfusion (Rest), T1-201 24 hour redistribution (Del) and Tc-99m-MIBI gated systolic thickening (Thk) for wall motion improvement after coronary artery bypass surgery. Materials and Methods: In 39 patients (M;F= 34:5, age $58{\pm}8$), preoperative and postoperative (3 months) SPECT were compared. 24 hour delayed SPECT was done in 16 patients having perfusion defects at rest. Perfusion or wall motion was scored from 0 to 3 (0: normal to 3: defect or dyskinesia). Wall motion was abnormal in 142 segments among 585 segments of 99 artery territories which were surgically revascularized. Results: After bypass surgery, ejection fraction increased from $37.8{\pm}9.0%$ to $45.5{\pm}12.3%$ in 22 patients who had decreased ejection fraction preoperatively. Wall motion improved in 103 (72.5%) segments among 142 dysfunctional segments. Positive predictive values (PPV) of Rev, Rest, Del, and Thk were 83%, 76%, 43%, and 69% respectively. Negative predictive values (NPV) of Rev, Rest, Del, and Thk were 48%, 44%, 58%, and 21%, respectively. Rest/gated stress/delay SPECT had PPV of 74% and NPV of 46%. Though univariate logistic regression analysis revealed Rev (p=0.0008) and Rest (p=0.024) as significant predictors, stepwise multivariate test found Rev as the only good predictor (p=0.0008). Conclusion: Among independent predictors obtained by rest T1-201/ stress gated Tc-99m-MIBI/ delayed T1-201 myocardial SPECT for wall motion improvement after bypass surgery, stress-rest reversibility was the single most useful predictor.

• The Korean Journal of Nuclear Medicine
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• v.35 no.6
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• pp.364-370
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• 2001

Purpose: In the revascuarization of ischemic dysfunctional myocardium, stunned myocardium was reported to recover function earlier than hibernating myocardium. It was also suggested that stunning and hibernation could be discriminated by reversibility of perfusion impairment on myocardial SPECT. In this study, we investigated the time course of functional recover after CABG according to reversibility of perfusion impairment. Materials and Methods: In 92 patients with coronary artery disease, Tl-201 rest/dipyridamole stress Tc-99m-MIBI gated SPECT was performed before, 3 months after, and 17 months after CABG. Using a 20-segment model, segmental perfusion and systolic thickening were automatically quantified. Perfusion-impaired segments with abnormal thickening were classified by reversibility into reversible (REV) and irreversible (IRREV) groups. The proportions of function-recovered segments were compared between groups and also between 3 months and 17 months in each group. Results: A total of 129 segments were Included In the analysis, and 76 were REV and 53 were IRREV. At 3 months after CABG, 61 segments (80%) in REV group showed functional recovery while 28 segments (53%) in IRREV group did (p<0.001). However, at 17 months after CABG, 60 segments (79%) in REV group and 37 segments (70%) un IRREV group showed functional recovery (p=n.s.). When comparing 3 months and 17 months in each group, REV group showed no difference, while IRREV group showed significant further improvement (p<0.05). Conclusion: In viable myocardium with ischemic myocardial dysfunction, the segments with reversible perfusion impairment recover function earlier after revascularization than irreversible segments.

• Journal of Korea Multimedia Society
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• v.16 no.7
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• pp.841-851
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• 2013

The infectious information hiding system(IIHS) is proposed for secure distribution of high quality video contents by applying optimized watermark embedding and detection algorithms to video codecs. And the watermark as infectious information is transmitted while target video is displayed or edited by codecs. This paper proposes a fast and effective reversible watermarking and infectious information generation for IIHS. Our reversible watermarking scheme enables video decoder to control video quality and watermark strength actively for by adding control code and expiration date with the watermark. Also, we designed our scheme with low computational complexity to satisfy it's real-time processing in a video codec, and to prevent time or frame delay during watermark detection and video restoration, we embedded one watermark and one side information within a macro-block. Experimental results verify that our scheme satisfy real-time watermark embedding and detection and watermark error is 0% after reversible watermark detection. Finally, we conform that the quality of restored video contens is almost same with compressed video without watermarking algorithm.

• Journal of Conservation Science
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• v.34 no.1
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• pp.23-29
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• 2018

This study synthesized poly-urea and used it as a filler material for the restoration of porcelain. The synthesized poly-urea was manufactured as a resin and hardener mix that does not undergo contraction during curing, and is unfading. Given an adhesion strength of $180kg/cm^2$ and shearing strength of $200kg/cm^2$, the synthesized poly-urea exhibited the same efficacy as the epoxy putty currently sold in the market. Moreover, it also overcame the drawback of foaming encountered by urethane restoratives, which are a structurally similar type. The hardening time and pot life could also be controlled using additives. The poly-urea used for the restoration of modern artifacts presented a pot life of approximately one hour and took 12 h for complete hardening ($T_{90}$). When a $2{\times}2{\times}2cm$-sized test sample was added to xylene, poly-urea started to separate approximately two hours later and completed perfect pulverization within the solution 24 h later, demonstrating its reversibility. When directly applied to contemporary artifacts, it demonstrated the potential for restoration, as well as convenience and colorfulness.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.464-470
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• 2010

The integrity of the industrial equipment in use under high temperature and high pressure must be assessed by regularly measuring the degraded mechanical properties during service time. In order to nondestructively monitor the degraded mechanical properties of industrial equipment, a measuring method of the reversible permeability(RP) using surface type probe is presented. The method for measuring the RP is based on that RP is the differential value of hysteresis loop. The RP is exactly the foundation hatmonics induced in a detecting coil measured by lock-in amplifier tuned to a frequency of the alternating perturbing magnetic field. The peak of RP is measured around the coercive force. Steel material used in this work was 12Cr ferritic heat resisting steel. The eleven kinds of samples aged during different times under same temperature ($700^{\circ}C$) were prepared. Peak interval of reversible permeability(PIRP), Vickers hardness, and tensile strength measured for the aged samples decreased abruptly for short aging time (below 500 h), but the change became small at a long aging time. Vickers hardness and tensile strength linearly decreased as RIRP decreased, so the degraded mechanical properties of 12Cr ferritic heat resisting steel could be nondestructively evaluated by measuring RIRP.

• Korean Journal of Environment and Ecology
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• v.17 no.1
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• pp.18-25
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• 2003

In order to know the effects of PCB(Arochlor 1248) on the oocyte maturation and proges-terone(P$_4$) production by FPH(Frog pituitary homogenate: 0.01 p.e/$m\ell$) of frog in vitro, the oocytes were cultured for 20 hours in presence of the PCB at various concentrations and exam-ined their maturation(germinal vesicle breakdown: GVBD) rates and P$_4$ levels secreted by the oocyte in the culture medium. The results show that PCB concentration of 10 ppb suppressed the maturation of the oocytes and secretion of P$_4$. To examine the reversibility of the inhibitory effects, the oocytes were exposed to the PCB only for 3 hours, and then transferred to plain medium and cultured further for 17 hours. The oocytes were recovered from the toxic effect of the PCB when they were exposed to 2.5 ppb, but not to 5 ppb of the PCB. These results indi-cate that PCB suppress the maturation of oocytes and secretion of p, at low concentration, sug-gesting that the frog oocyte culture system can be used as a useful tool to evaluate the toxicity of the pollutants in the environment.

• Journal of Conservation Science
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• v.31 no.1
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• pp.37-46
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• 2015

In the case of adhesives & restoration agents currently being used for the preservation treatment of ceramics and earthenware, epoxy type, cellulose type and cellulose type are mainly being used. However, they are showing various problems such as re-detachment from severe contraction, color change from yellowing, work inconvenience of staining on tools and hand during usage and irreversibility. For the purpose of solving the issues of yellowing and irreversibility of epoxy resin being used to restore ceramics, urethane synthetic resin with low yellowing excellent reversibility has been developed in this study. The adhesive strength of urethane resin that has been developed has excellent properties with 2.07MPa for undiluted solution, which is 1.5 times higher than that of existing material EPO-$TEK301^{(R)}$ 1.21MPa. The result of workability measurement showed that the wear rate of urethane resin (in Talc 50wt%) was 1.09%, which was somewhat higher than that of existing material Quick $Wood^{(R)}$ (1.02%). In addition, its wear rate is two times higher than that of $EPO-TEK301^{(R)}$ (0.41%) and $L30^{(R)}$ (0.39%), thereby showing an advantage in its forming process compared to existing materials. As for the advantage of urethane resin of reversibility experiment, 12 hours after acetone, ethyl alcohol deposition, urethane resin and filler talc were dissolved 100% while showing powdering phenomenon. Compared to 0% reversibility of existing epoxy resin, it has much superior reversibility. The result of UV rays experiment to evaluate its durability showed that ${\Delta}E^*ab$ color change value based on undiluted solution of urethane resin was 2.76 before & after UV rays exposure, which was a decrease by about 7-20 times compared to that of existing resin, thereby minimizing the issue of heterogeneity.