• Journal of dental hygiene science
• /
• v.17 no.6
• /
• pp.481-486
• /
• 2017

The study aimed to compare the whitening efficacy of a strip and gel containing 2.9% hydrogen peroxide, using a tooth whitening light activator. The whitening effect was compared through in vitro and in vivo studies. In the in vitro study, we used stained hydroxyapatite (HAP) specimens as artificial teeth. HAP specimens were made using HAP powder and polyvinyl alcohol solution, and stained by modified Stookey's method. A whitening gel and whitening strip were applied to the respective specimens for 20 minutes, with a light activator. The color changes were measured using a colorimeter. In the in vivo study, one group (test 1) used the gel with a light activator and the other group (test 2) used a strip with the same activator for 15 minutes a day, for four consecutive days. An organoleptic evaluation using a Vita shade guide and instrumental evaluation using a Shade eye-NCC (Shofu Co., Japan) were performed. The color change values (${\Delta}E^*$) in the in vitro study revealed the strip with the light activator to be more effective than the gel with the same activator (p<0.001). In the in vivo study, even though there was no significant difference between the groups with respect to the ${\Delta}E^*$, using either the Shade eye-NCC or the Vita shade guide, the change in yellowness (${\Delta}b^*$) was statistically significant (p=0.024). In conclusion, test 2 group that used 2.9% hydrogen peroxide strip with a light activator, showed a tendency towards increased whitening than test 1 group that used the gel with the same activator; however further studies are needed to validate the above finding.

• Management & Information Systems Review
• /
• v.34 no.3
• /
• pp.125-140
• /
• 2015

KOSDAQ market reorganized their division system from two types to four types of division departments such as blue chip, venture, medium, and technology development departments in 2011. However, under the current new division system, financially unhealthy firms attempting to take advantage of the classifying opportunity of blue chip department are likely to engage in pernicious earnings management. The objective of this study is to investigate the earnings management behavior surrounding the time of KOSDAQ firms entering the blue chip department via new division system. More specifically, we test whether the firms classified blue chip department tend to engage in upward earnings management using accruals and real activities before and after they achieve blue chip status. In this study, we analyzed 111 firms classified blue chip department in 2011 according to new division system in KOSDAQ market. Major test results indicate that firms entering the blue chip department according to current KOSDAQ division system in general, tend to inflate reported earnings by means both of accruals and real activities right before the entering year. This result suggests that the firms classified blue chip department engage in opportunistic earnings management with a view to uplifting their market values. Our study is expected to provide clues useful for searching policy directions which intend to ameliorate adverse side effects of the current KOSDAQ division system. In sum, the regulatory authorities and enforcement bodies need to exercise caution in deliberating more stringent review procedures so that financially healthy and promising candidates are properly segregated from their poor and risky counterparts, thus enhancing the beneficial effects, while mitigating adverse side effects of the system.

• The Transactions of the Korea Information Processing Society
• /
• v.5 no.5
• /
• pp.1257-1263
• /
• 1998

To realize a highly reliable satellite-base data distribution system efficiently, a hierarchical distributed control network which utilizers a sub control station(SCS) in addition to a hub and a user station(US) is proposed and evaluated. The results show that there exists an optimum number of sub control stations that minimizes the polling processing time as a parameter of the processing time ratio between US-SCS and SCS-CS links. From a viewpoint of the control network cost, it is shown that the cost can be less compared to the conventional one, when the communication cost between the US and SCS is slightly reduced.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2010.11a
• /
• pp.1558-1559
• /
• 2010

본 논문에서는 휴대 단말기를 이용하여 시각장애인들을 위한 장애물 안내시스템을 설계 및 구현한다. 휴대성을 높이기 위해 시스템을 주제어기와 부제어기로 분리시키고, Zigbee 통신을 이용하여 두 디바이스 간에 정보를 주고 받는 형태로 설계하였다. 주제어기는 부제어기로부터 전송된 전방의 장애물 정보를 취합하고 판단하여 사용자에게 제공하는 기능을 하고, 부제어기는 6개의 초음파 센서를 갖는 모듈로서 초음파센서를 이용하여 전방 장애물과의 거리를 지속적으로 측정하여 주제어기로 전송하는 기능을 한다. 최근 이슈가 되고있는 Android O/S 기반의 휴대용 단말기를 기반으로 설계 및 구현하였기 때문에 Android O/S 기반의 다양한 휴대용 단말기에 적용이 가능하다.

• Journal of the korean veterinary medical association
• /
• v.17 no.2
• /
• pp.21-24
• /
• 1981

• Korea Petroleum Association Journal
• /
• no.2 s.168
• /
• pp.38-41
• /
• 1995

• Journal of the korean veterinary medical association
• /
• v.28 no.5
• /
• pp.261-266
• /
• 1992

• 월간낙농육우
• /
• s.34
• /
• pp.38-40
• /
• 1984

• 월간낙농육우
• /
• s.76
• /
• pp.52-55
• /
• 1988

• Korean Deer Journal
• /
• v.2 no.4 s.9
• /
• pp.48-49
• /
• 1997