• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.51 no.2
• /
• pp.179-187
• /
• 2015

Experiments designed to measure the effect of LED (light-emitting diode) light wavelength on the growth of fingerling rockfishes (Sebastes inermis) were conducted. Fingerling rockfishes (average body weight of individual: 1.13g) were divided into two groups by wavelength of the LED light [light power: 1,620 mW; wavelength: 518 nm (green color), 622 nm (red color)]. Triplicate groups of 180 individuals were reared over 7 weeks. Lighting duration was 14 hours from 06:00 to 20:00. A water tank exposed on the natural light in a room through the windows was used as a control. At results of the first experiment [initial average body weight (BW) of individual: 1.13 g; standard deviation (SD): 0.13 g], the final individual BW exposed on the green color was increased 0.39 g than the red color, and decreased 0.12 g than the natural light in the room. At results of the second (initial individual BW: 5.07 g; SD: 0.70 g) and the third experiment (initial individual BW: 10.67 g; SD: 0.67 g), the final individual BW exposed on the green color was increased 1.07 g and 2.55 g than the red color, respectively, and increased 0.57 g and 0.84 g than the natural light, respectively. The relative growth rate of the green color was higher about 8% significantly (p<0.05) than the natural light. In the case of the red color the relative growth rate was lower significantly (p<0.05) than the natural light.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.4 no.6
• /
• pp.1098-1115
• /
• 2010

An inseparable challenge associated with every random access network is the design of an efficient Collision Resolution Algorithm (CRA), since collisions cannot be completely avoided in such network. To maximize the collision resolution efficiency of a popular CRA, namely Binary Exponential Backoff (BEB), we propose a reactive backoff algorithm. The proposed backoff algorithm is reactive in the sense that it updates the contention window based on the previously selected backoff value in the failed contention stage to avoid a typical type of collision, referred as cross-collision. Cross-collision would occur if the contention slot pointed by the currently selected backoff value appeared to be present in the overlapped portion of the adjacent (the previous and the current) windows. The proposed reactive algorithm contributes to significant performance improvements in the network since it offers a supplementary feature of Cross Collision Exclusion (XCE) and also retains the legacy collision mitigation features. We formulate a Markovian model to emulate the characteristics of the proposed algorithm. Based on the solution of the model, we then estimate the throughput and delay performances of WLAN following the signaling mechanisms of the Distributed Coordination Function (DCF) considering IEEE 802.11b system parameters. We validate the accuracy of the analytical performance estimation framework by comparing the analytically obtained results with the results that we obtain from the simulation experiments performed in ns-2. Through the rigorous analysis, based on the validated model, we show that the proposed reactive cross collision exclusionary backoff algorithm significantly enhances the throughput and reduces the average packet delay in the network.

• Archives of design research
• /
• v.12 no.1
• /
• pp.15-24
• /
• 1999

The deVelopment of technologies changes the thinking of people and the ways of IMngs. The software developers as well as users are now aware of the importance of graphic user interface design, and the usage of graphic elements is getting rrore and more easier due to the technological improvements based on the windows system(Microsoft). For these reasons, people who engaged in software developments do much more efforts to get user-oentered design solutions, in other words, the usability improvements. And the interdisciplinary projects teams which consist of experts of various fields are increasing in number. But, the lack of understanding on software developments and the proceeding of design work without the consideration of entire process of a project make interface design work difficult. For exampIe, some engineers often think designers as persons who decorate their products in the final stage. In this thesis, through the investigation of user interface design and software development process, the frarnework of effective team projects is proposed. The main purposes of this thesis are to define the work area and position of designers and to propose the interface design process for the cooperative software development projects within the interdiociplinary teams.

• Fire Science and Engineering
• /
• v.32 no.5
• /
• pp.57-66
• /
• 2018

A sports center fire in Jecheon that caused 29 deaths and 40 injuries was analyzed based on initial response and management in order to investigate the causes of the casualties. The aspects of initial response included delay of reporting 119, not being guided to the exit for the body scrubber on the $2^{nd}$ floor for escape, opening the fire doors of the exits on the $1^{st}$ floor and $3^{rd}$ floor, not closing the fire door of the main stairs on the $3^{rd}$ floor, and not doing an emergency broadcast. The management aspects included closing the alarm valve of the sprinkler system on the $1^{st}$ floor, starting-stop of the fire pump controller, neglecting leakage of water and electricity between the false ceiling and ceiling in the parking lot, hiding the exit light in the ladies bathroom lounge on the $2^{nd}$ floor and piling up things in the exit, neglecting the button of an automatic door on the $2^{nd}$ floor, conventional fire safety management, insufficient inspection of fire equipment, and not working fire shutters and smoke exhaust windows.

• Journal of the Korean housing association
• /
• v.20 no.2
• /
• pp.77-86
• /
• 2009

The purpose of this study was to examine the household characteristics, the actual residential environment of the elderly living with their offsprings together in Gwangju. We also evaluated their satisfaction with the needs for remodeling of their houses and the different opinions about those things between the elderly and their off springs. We used comparative and descriptive T-test in statistical analysis. The results were as follows. There were more families living in the detached houses than those living in the apartments. The average size of the houses was 100.8 square meters. The mean residence period was 13.5 years. The sons were usually the legal householders. The residents who experienced remodeling before reassigned the furniture and installed the bathtub, which was designed to be sat on comfortably in a common. A few residents installed safety system such as alarms for incident fire or gas, convenient knobs for handling and faucets for running hot or cold water separately. After the installation of alarms, convenient knobs of windows or door, Customer satisfaction for those things were quite high. But that for the installation of safety bar were the lowest in contrast. The most things the old wanted to change were to rearrange bedrooms and bathrooms on the first floor and to decorate them in westernized styles. They didn't need to set up safety bars or shower instrument for modulating heights. The second generation wanted to install the blinds or curtains more than the third generations.

• KIEAE Journal
• /
• v.14 no.3
• /
• pp.39-45
• /
• 2014

Energy poverty has been defined as low-income households who paid energy cost more than 10% of their ordinary income. Therefore, there are various subsidy programs focused on house remodeling for low-income households and one of them is the Home Energy Efficiency Assistance Program which have done by Korea Energy Foundation since 2007. The aim of the program is to improve the thermal performance of dilapidated dwellings and analyzed the detached house for the low-income households to develop the building typology. The database contained approximately 3,061 households which was obtained from the program in 2013 and the results of the study were like this; 1) For the shape of residential houses, the number of rectangular shaped building was higher than non-rectangular shaped ones. 2) For the orientation of buildings, the south layout of the detached housing was dominant to gain heating energy into buildings. 3) For the floor area, the average floor area was $44.2m^2$, although its size varied wide variations, which range from $6.3m^2$ to $107.1m^2$. 4) For the windows and doors, the south-facing window was larger than the other side. Finally it would be possible to determine the characteristics of residential houses for low-income families. A future study could establish typology of low-income housing that it would estimate the performance of each model building before and after the retrofit to improve the energy performance.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.4A
• /
• pp.412-420
• /
• 2006

With the appearance of various types of traffic services in communication networks, a study on QoS(Quality of Service) packet scheduling mechanisms which can support differentiated service to each traffic service becomes very important. To meet this requirement, IEEE 802.11 Working Group established the IEEE 802.11e MAC protocol which categorizes every traffic services into 4 access categories(AC) and provides the differentiated service to each AC. In addition, the physical layer of IEEE 802.11a/g standards provide up to 54 Mbps transmission rate per one wireless LAN terminal. However, since the radio resource is hardly limited in wireless channel, it is necessary to find an efficient packet scheduling scheme to maximize the transmission efficiency. Therefore, in this paper, we proposed a new packet scheduling scheme that can enhance the total throughput by setting different contention windows(CW) of CSMA-CA channel access scheme to each wireless LAN terminal according its current channel states. Numerical results derived from using NS-2 network simulator have shown that our proposed packet scheduling scheme can enhance the performance of IEEE 802.11e more and more.

• Journal of Technologic Dentistry
• /
• v.38 no.3
• /
• pp.111-117
• /
• 2016

Purpose: The present study was performed to investigate the effect of abutment inclined angle on the marginal fit of zirconia all-ceramic crown. Methods: The Ti abutments with 3 different inclined angle($2^{\circ}$, $4^{\circ}$ and $6^{\circ}$) were fabricated. The zirconia copings were fabricated for each abutment by using dental CAD/CAM system. The manufactured zirconia copings were duplicated through silicone replica technique, and a replicated specimen was sectioned in the center of bucco-lingual and mesio-distal axial to measure the marginal fit by using a stereo microscope. The results were analyzed using a one-way ANOVA with SPSS 22.0 for Windows(${\alpha}=0.05$). Results: On the bucco-lingual axial, marginal fit was the RL3($41.5{\pm}3.4{\mu}m$), RL2($44.3{\pm}4.3{\mu}m$) and RL1($47.5{\pm}5.7{\mu}m$), respectively. On the mesio-distal axial, marginal fit was the RL3($41.1{\pm}3.7{\mu}m$), RL2($45.7{\pm}5.3{\mu}m$) and RL1($46.2{\pm}4.5{\mu}m$), respectively. One-way ANOVA showed statistically significant difference between groups for marginal fit(p<0.05). Conclusion: For marginal fit of the abutments inclined angle, RL3 specimen was superior. The abutment inclined angle had influence on marginal fit of the zirconia copings. The marginal fit of each group were within clinically acceptable range.

• Journal of the Korea Society of Computer and Information
• /
• v.15 no.2
• /
• pp.155-162
• /
• 2010

To ensure accurate measurements of wireless network performance, it should be collected real-time data which are transmitted between a large number of nodes in the actual network environment. Therefore, it is necessary to develop simulation tool for finding optimal network system design method such as media access control, routing technique, ad-hoc algorithm of node deployment while overcoming spatial and temporal constraints. Our research attempts to provide an improved architecture and design method of simulation tool for wireless network is an application of multi-threading technique in these issues. We finally show that usability of the proposed simulator by comparing results derived from same test environment in the wireless LAN model of our simulator and widely used network simulation package, NS-2.

• Journal of Adhesion and Interface
• /
• v.16 no.1
• /
• pp.15-21
• /
• 2015

In this study, rheological properties and flow dynamics in roll coating process of basecoat paints have been investigated for automotive precoated metal (PCM) sheet applications. Various rheological properties for basecoats with three colors (black, blue, and silver), such as shear viscosity data at room temperature and elastic/viscous moduli under thermal curing condition, have been measured using a rotational rheometer. It is found that the relative portion of function groups inside basecoats and their viscosity level have greatly affected the formation of crosslinked networks by thermal curing. Also, operability coating windows for basecoats have been established in three-roll coating process system by observing their flow instabilities such as ribbing and cascade. It is confirmed that rheological approaches applied in this study have been usefully applied to develop environmentally-friendly PCM coating technology and optimally control the coating operations for non-Newtonian PCM paints.