• Journal of Marine Life Science
• /
• v.4 no.1
• /
• pp.14-21
• /
• 2019

This review paper discussed the decadal fluctuations in the catch of the common squid, Todarodes pacificus (T. pacificus) by focusing on migration and distribution patterns. Since 1980s, changes in T. pacificus catches were due to climate regime shift in Korean waters. Fluctuation patterns of catches were different between the East Sea and the Yellow Sea. Generally PDO (Pacific Decadal Oscillation) phase shows a negative correlation with strength of warm current to the East Sea. In 1980s when PDO was positive phase (+), T. pacificus catch was higher in the Yellow, but it was lower in the East Sea. In 1990s when PDO was negative phase (-), T. pacificus catch showed opposite trend compared with 1980s. Such spatial and decadal fluctuations of T. pacificus catch were due to its northward migration along with the warm current or southward movement against the current. In the East Sea, strong (weak) warm current period, the current path has been shifted toward the East Sea coast of Korea (central East Sea or the coast of Japan). It has a correlation with PDO. In the positive PDO phase (1980s), the fishing ground was located on the eastern side of Ulleungdo, whereas during negative PDO phase (1990s), they were situated near the southeastern coast of the Korean peninsula. In the 1980s, volume transport passing into the Yellow Sea increased, whereas volume transport in the East Sea decreased. This is one of major reason increasing T. pacificus larvae in the Yellow Sea.

• Journal of Biosystems Engineering
• /
• v.38 no.2
• /
• pp.138-148
• /
• 2013

Purpose: Determining an appropriate path is a top priority in order for a robot to maneuver in a dynamically efficient way especially in a pick-and-place task. In a non-standardized work environment, current robot arm executes its motion based on the kinematic displacements of joint variables, though resulting motion is not dynamically optimal. In this research we suggest analyzing and applying motion patterns of the human arm as an alternative to perform near optimum motion trajectory for arbitrary pick-and-place tasks. Methods: Since the motion of a human arm is very complicated and diverse, it was simplified into two links: one from the shoulder to the elbow, and the other from the elbow to the hand. Motion patterns were then divided into horizontal and vertical components and further analyzed using kinematic and dynamic methods. The kinematic analysis was performed based on the D-H parameters and the dynamic analysis was carried out to calculate various parameters such as velocity, acceleration, torque, and energy using the Newton-Euler equation of motion and Lagrange's equation. In an attempt to assess the efficacy of the analyzed human motion pattern it was compared to the virtual motion pattern created by the joint interpolation method. Results: To demonstrate the efficacy of the human arm motion mechanical and dynamical analyses were performed, followed by the comparison with the virtual robot motion path that was created by the joint interpolation method. Consequently, the human arm was observed to be in motion while the elbow was bent. In return this contributed to the increase of the manipulability and decrease of gravity and torque being exerted on the elbow. In addition, the energy required for the motion decreased. Such phenomenon was more apparent under vertical motion than horizontal motion patterns, and in shorter paths than in longer ones. Thus, one can minimize the abrasion of joints by lowering the stress applied to the bones, muscles, and joints. From the perspectives of energy and durability, the robot arm will be able to utilize its motor most effectively by adopting the motion pattern of human arm. Conclusions: By applying the motion pattern of human arm to the robot arm motion, increase in efficiency and durability is expected, which will eventually produce robots capable of moving in an energy-efficient manner.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.41 no.10
• /
• pp.103-108
• /
• 2004

In this paper, a compact patch antenna with four T-slits fed by crossed aperture coupling is proposed for miniaturized Portable GPS handsets. The mechanism for compact size antenna is investigated with the behavior of the currents on the radiating patch. The equivalent surface current path due to the slits is lengthened, reducing the resonant frequency at a fixed patch size. The results of embedded T-slits for compact antenna size show that the resonant frequency is significantly lowered from 2.545GHz to 1.575GHz, corresponding to a 44.65% antenna size reduction compared to reference design. Experimental results show that good CP radiation patterns are obtained and impedance bandwidth (VSWR $\leq$ 2), 3dB axial ratio are about 21MHz, 19MHz at the center resonant frequency, respectively.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.52 no.9
• /
• pp.418-423
• /
• 2003

This paper describes an electronic compass using micromachined X- and Y-axis micro fluxgate sensors which were perpendicularly aligned each other to measure X- and Y-axis magnetic fields respectively. The fluxgate sensor was composed of rectangular-ring shaped magnetic core and solenoid excitation(49 turns) and pick-up(46 turns) coils. Excitation and pick-up coil patterns which were formed opposite to each other wound the magnetic core alternatively to improve the sensitivity and to excite the magnetic core in an optimal condition with reduced excitation current. The magnetic core has DC effective permeability of ~1000 and coercive field of ~0.1 Oe. The magnetic core is easily saturated due to the low coercive field and closed magnetic path for the excitation field. To decrease the difference of induced second harmonic voltages from X- and Y-axis, excitation condition of 2.8 $V_{P-P}$ and 1.2 MHz square wave was selected. Excellent linear response over the range of -100 $\mu$T to +100 $\mu$T was obtained with 210 V/T sensitivity. The size of each micro fluxgate sensor excluding pad region was about 2.6${\times}$1.7 $mm^2$ and the power consumption was estimated to be 14 mW.W.

• The Journal of Information Systems
• /
• v.17 no.4
• /
• pp.341-367
• /
• 2008

This study propose a model relating supplier's use of IOIS(Inter-Organizational Information Systems) to strategic benefits through extension of Subramani's research model. In extended model, collaboration serves as a safeguard for relationship-specific intangible asset. Specifically, we evaluate how two patterns of IOIS use by supplier(exploitation and exploration) relate to two specific types of relationship-specific intangible asset(business process specificity and domain knowledge specificity), which in turn are posited to promote collaboration and strategic benefits. To explore the current study, questionnaire survey was conducted on 72 first-tier supplier firms in the manufacturing industry. Based on the survey results, we posits the following : (1) Each pattern of IOIS use directly promotes a specific type of relationship-specific intangible asset. The path of the relationship between IOIS use for exploitation and domain knowledge specificity is positive but not significant. The other paths are positive and significant. (2) Both types of relationship-specific intangible asset have a positive and significant impact on collaboration. (3) Domain knowledge specificity influences on strategic benefits but business process specificity does not have an effect on them. (4) Collaboration affects supplier's strategic benefits. These findings provide a deeper understanding of the mechanism of how the pattern of IOIS use can result in strategic benefits for supplier firms.

• Journal of the Korean association of regional geographers
• /
• v.22 no.3
• /
• pp.483-498
• /
• 2016

This study investigated the conceptualization and application of new concept of regional resilience with case study in Korea in order to promote more sustainable regional development strategies, while problematizing dominant regional competitiveness concept in the current regional development circle under the condition of stagnant growth and ever-existing crisis in these days. Through literature review, this paper found out that regional resilience is a useful concept both to understand dramatic regional changes and to promote new regional development strategies. Furthermore, the study formulated basic research topics and issues for regional resilience through reviewing existing research outcomes on the measurement and factors of regional resilience. Through case study of two macro city-regions in Korea, this study also found out that regional resilience patterns and processes are differentiated according to the place and its scale and that both regional industrial structure formed in a path-dependent way and regional competitive characteristics are all significant to understand the regional resilience patterns and processes.

• Journal of Advanced Marine Engineering and Technology
• /
• v.34 no.6
• /
• pp.922-934
• /
• 2010

To arrange artificial reefs for marine afforestation effectively, tidal currents were analyzed by numerical experiments, and particle tracking based on tidal currents was carried out to clarify the path of algae spores. The experiments were conducted by the Environmental Fluid Dynamics Code (EFDC), and water column was vertically divided into five layers. Tidal current patterns were showed to be affected by main currents outside of the study area, and two circle currents were observed during the analysis of residual currents. Particle tracking lasted 15 days at three installation places where artificial reefs for marine afforestation could be deployed. According to the results of the particle tracking experiment, particle movements at the No.1 and No. 3 stations were belt types along the coastal line. The No. 2 station documented an ellipse type movement 300~500m from coast line. These results suggest that artificial reefs for marine afforestation should be installed in the belt zones at of the No. 1 and No. 3 stations, and in the ellipse zone at the No. 2 station.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.24 no.2
• /
• pp.351-373
• /
• 2019

The cold eddies around the Ulleung Basin in the East Sea were identified from satellite altimeter sea level data using the Winding-Angle method from 1993 to 2015. Among the cold eddies, the Dokdo Cold Eddies (DCEs), which were formed at the first meandering trough of the East Korea Warm Current (EKWC) and were pinched off to the southwest from the eastward flow, were classified and their migration patterns were analyzed. The vertical structures of water temperature, salinity, and flow velocity near the DCE center were also examined using numerical simulation and observation data provided by the Hybrid Coordinate Ocean Model and the National Institute of Fisheries Science, respectively. A total of 112 DCEs were generated for 23 years. Of these, 39 DCEs migrated westward and arrived off the east coast of Korea. The average travel distance was 250.9 km, the average lifespan was 93 days, and the average travel speed was 3.5 cm/s. The other 73 DCEs had moved to the east or had hovered around the generated location until they disappeared. At 50-100 m depth under the DCE, water temperature and salinity (T < $5^{\circ}C$, S < 34.1) were lower than those of ambient water and isotherms made a dome shape. Current faster than 10 cm/s circulates counterclockwise from the surface to 300 m depth at 38 km away from the center of DCE. After the EKWC separates from the coast, it flows eastward and starts to meander near Ulleungdo. The first trough of the meander in the east of Ulleungdo is pushed deep into the southwest and forms a cold eddy (DCE), which is shed from the meander in the south of Ulleungdo. While a DCE moves westward, it circumvents the Ulleung Warm Eddy (UWE) clockwise and follows U shape path toward the east coast of Korea. When the DCE arrives near the coast, the EKWC separates from the coast at the south of DCE and circumvents the DCE. As the DCE near the coast weakens and extinguishes about 30 days later after the arrival, the EKWC flows northward along the coast recovering its original path. The DCE steadily transports heat and salt from the north to the south, which helps to form a cold water region in the southwest of the Ulleung Basin and brings positive vorticity to change the separation latitude and path of the EKWC. Some of the DCEs moving to the west were merged into a coastal cold eddy to form a wide cold water region in the west of Ulleung Basin and to create a elongated anticlockwise circulation, which separated the UWE in the north from the EKWC in the south.

• Journal of the Korean housing association
• /
• v.19 no.2
• /
• pp.115-124
• /
• 2008

This study explores the beneficial methodology to increase cultural values of urban style Hanok, Korean traditional residence. Based on the literary geographical approach, this study defines the physical identities of special Bukchon Hanok area in Seoul. The explored physical identities are to provide basic fundamentals for supplying and maintaining new Hanok buildings, including how to preserve and restore the traditional Hanok areas. They are also to develop various Hanok related cultural products and to encourage Hanok popularization. In addition, this study is to add more the humane values and significances to the previous relevant researches. With these perspectives and through above mentioned methodology, the study draws the physical identities of Bukchon Hanok area and meanings as belows: The first one is the collective identity. Bukchon Hanok area is mainly composed of organic spaces with its collective scenary. Narrow alleys and curved lanes created by collective gaps between Hanok buildings, provide residents and visitors with abundant choices of moving path. The second one is the formal identity. Bukchon Hanok maintain their unique layout patterns. The basic units of Chae are combined in specific ways such as 'ㄱ', 'ㄷ', 'ㅁ' types and result typical formal expression of the area. The third one is grounding identity which represent the relationship between the earth and every-day living space. Each Chaes of house always surround Madang, Korean traditional court yard with rare vegetation. And the connection to the ground is transferred to the memories of its dwellers. Lastly, the current Hanok still preserve similar characteristics of past time Hanok such as materials, structure and styles by using unique building technics and exposing traditional ornamenting styles.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.1
• /
• pp.15-22
• /
• 2018

In this paper, a microstrip-fed triple-band monopole antenna for WLAN/WiMAX applications was proposed. The proposed antenna is consist of two arc-shaped and one strip line structure, then get the three current path and then designed in order to get triple resonant characteristics. We carried out simulation about parameters. Taking account of coupling effect, Adjusted the length of the two arc-shaped and one strip line, we get the optimized parameters. The proposed antenna is fabricated on an FR-4 substrate, the dielectric constant is 4.4, and total size is $23.5mm(W1){\times}32.0mm(L1){\times}1.0mm(t)$, and its proposed antenna size is $21.0mm(W6){\times}31.0mm(L7)$. From the measured results, return loss of the proposed antenna satisfied return loss 927 MHz (1.844~2.771 GHz), 926 MHz (3.33~4.256 GHz), and 1,415 MHz (5.13~6.545 GHz). And measured results of gain and radiation patterns displayed for operating bands.