• Journal of Navigation and Port Research
• /
• v.28 no.5
• /
• pp.429-434
• /
• 2004

In this paper, we designed a reconfigurable slot antenna using sequentially voltage-applied RF MEMS switches. In order to obtain pull-in voltage and maximum stress of the MEMS switches, the switch structures in accordance with airgap height was analyzed by ANSYS simulation A actuation voltage of MEMS switches can be determined by switch geometry and airgap height between a movable plate and a bottom plate. The designed lengths of MEMS switches were 240 $\mu\textrm{m}$, 320 $\mu\textrm{m}$, 400 $\mu\textrm{m}$, respectively and the airgap was 6$\mu\textrm{m}$. The total size of the designed slot antenna was 10 mm x 10 mm and the slot length and width were 500 $\mu\textrm{m}$ and 200 $\mu\textrm{m}$, respectively. The length and size of the CPW feedline were 5 mm and 30-80-30 $\mu\textrm{m}$, respectively. and then the size of the CPW in the slot was 50-300-150 $\mu\textrm{m}$. The tuning of the resonant frequency of the proposed device is realized by varying the electrical length of the antenna, which is controlled by applying the DC bias voltages to the RF MEMS switches. The designed slot antenna has been simulated, fabricated and measured.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.12
• /
• pp.118-125
• /
• 2017

In this study, we examined the bond performance of FRP Hybrid Bars. FRP Hybrid Bars are developed by wrapping glass fibers on the outside of deformed steel rebars to solve the corrosion problem. The surface of the FRP Hybrid Bars was coated with resin and silica sand to enhance its adhesion bonding performance with concrete. Various parameters, such as the resin type, viscosity, and size of the silica sand, were selected in order to find the optimal surface condition of the FRP Hybrid Bars. For the bonding test, FRP Hybrid Bars were embedded in a concrete block with a size of 200 mm3 and the maximum load and slip were measured at the interface between the FRP Hybrid Bar and concrete through the pull-out test. From the experimental results, the maximum load and bond strength were calculated as a function of each experimental variable and the resin type, viscosity and size of the silica sand giving rise to the optimal bond performance were evaluated. The maximum bond strength of the specimen using epoxy resin and No. 5 silica sand was about 35% higher than that of the deformed rebar.

• Journal of Korean Ophthalmic Optics Society
• /
• v.6 no.1
• /
• pp.13-29
• /
• 2001

A mathematical model was proposed to analyze the vibration of diaphragm, such as the contact lenses fitted on the eyes, being subjected to the external sinusoidal pressure. The model incorporates the differential equations and their numerical solution program, based on the wave equations. Turbo-C and graphic software, formulated to describe the dependence of the various parameters involved in the vibration. The model predicts the radial distribution of amplitude, frequency dependence of both average displacement amplitude and the power of diaphragm whose edge is being either simply supported or rigidly clamped in vibration. The effect of variables such as thickness, radius, damping coefficients on the vibration characteristics was illustrated by the computer simulation of the derived program. As the frequency of driving pressure increases above the certain value determined by the boundary conditions and parameters the wave shape or pattern changes from simple arc to belly or loops having double antinode. It seems that the effect of outer antinode progressively increases as the frequency increases. If this kind of phenomena occurs to the contact lens on the cornea in vivo, it may cause an abnormal correction power in the lenses or pull off the eye due the increased rise of outer part of the lens.

• Journal of Pharmacopuncture
• /
• v.13 no.2
• /
• pp.93-100
• /
• 2010

Background: Auricular acupressure is one of the traditional health care treatments in oriental medicine. Approximately, 30~40% of the cancer patients have said to be suffering from insomnia and half of them having chronic and severe insomnia at the same time. Insomnia caused cancer patients feel more pain, fatigue, depression and anxiety and it sometimes let the power to have the best of cancer pull down. Objective: To investigate how effective the auricular acupressure treatment to cancer patients suffering from insomnia. Methods: We recruited participants from East-West Cancer Center of Daejeon University. Finally, of the people whose age range from 20 to 75, 12 patients who got less than 40 points from the score of Oh's sleeping score (OSS) were recruited. Single-blind, randomized pilot study was performed. The treatment group received auricular acupressure treatment (AAT) on active points and the control group had received sham acupressure treatment (SAT) for five times. Sleep parameters were checked by using OSS and numeric rating scale (NRS). We checked the scale everytime, both before and after treatment. We analyzed the data statistically by using independent T-test, paired T-test and analysis of variance (ANOVA) test. (p<0.05) Results: Twelve cancer patients participated in this pilot study and there was no significant difference between control and treatment group. Only 7 of them had completed the whole treatment process, 4 patients of AAT group and 3 participants of SAT. The OSS of AAT group had increased from $34.0{\pm}4.3$ to $39.5{\pm}3.1$ and that of SAT group had increased from $38.3{\pm}3.5$ to $40.0{\pm}0.0$. There was no significant difference between them. The NRS of AAT group had increased from $6.3{\pm}2.9$, $04.8{\pm}2.1$ and that of SAT group had increased from $7.0{\pm}1.0$ to $5.0{\pm}2.6$. No significant difference was observed between them. Conclusion: Although both groups did not show significant differences, most of the experimental participants showed increasing OSS and NRS after treatments. Significant participants' number will be needed in the next study.

• Journal of the Korean association of regional geographers
• /
• v.8 no.4
• /
• pp.430-450
• /
• 2002

This study empirically analyses the spatial features of land use and transportation, and residential characteristics of the cases of the Sangin and Siji newly developed districts in Taegu. Before the development, the areas consisted mainly of rice paddies and fields; these areas are now filled with high-density residential complexes, with a proliferation of commerce and service functions. In Sangin, restaurants, retail services, bars and bakeries are the main developments, but Siji developed retail services, restaurants, private institutions for students, and facilities for convenience goods. While the public transportation system is oriented to CBD, the inter-districts transportation network is lacking. The residents are mainly in their 40s to 50s, with white collar jobs. They have a relatively high level of education with high income. They have migrated a relatively short distance to the district. The locational(pull) factors influencing the decision to migrate, for Sangin are transportation, the physical environment and access to the working place, but for Siji it has been the physical environment, the school group, and access to the working place. The main dissatisfaction factors for Sangin are the management fee, the school group and for Siji they are commuting, the management fee and transportation.

• Economic and Environmental Geology
• /
• v.41 no.3
• /
• pp.275-286
• /
• 2008

The Sambo gold deposit located nearby the Cretaceous Hampyeong basin is composed of gold quartz fine vein(the Jija vein) within Cretaceous rhyolite showing $N10{\sim}20W$ trends as well as $N5{\sim}10E$ trending quartz veins(the Pungja, Gwangsan and Pungjaji veins) in Precambrian gneiss. The gold vein typically displays the intermittent and irregular fine veins within rhyolite. Electrum is disseminated in wallrock along the fine cracks as well as coexists with hematite replacing pyrite. Ore-forming fluids from the mineralized vein($H_2O/-NaCl$ system, Th; $340{\sim}200^{\circ}C$, Salinity <2.7 eq. wt.% NaCl) and NE-trending veins($H_2O-NaCl/-CO_2$ system, Th; $400{\sim}190^{\circ}C$, salinity <7.9 eq. wt.% NaCl) are featured by dissimilar physicochemical conditions but their fluid evolution trends(boiling and mixing) are similar with each other. Gold veins of the Sambo deposit filled along NNW-trending tension crack are related to pull-apart basin evolution. Selective gold mineralization of the deposit reflect to dissimilarity between two ore-forming fluid sources. Consequently, gold veining of the Sambo deposit formed at shallow-crustal level and could be categorized into epithermal-type gold deposit related to tensional fractures filling triggered by Cretaceous geodynamics.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2000.11b
• /
• pp.489-497
• /
• 2000

Since Chinese cabbages weigh 3 to 5kgf and are big in size at the time of harvest, handling operations such as harvesting, loading and unloading including transportation require the highest labor demand among all other cultivation processes. Recently, though several cabbage harvesters were developed in Japan and Europe, those harvesters were not suitable for Chinese cabbages cultivated in Korea because of the size and shape. The cabbage harvester is almost meaningless without any proper cabbage piling and pallet unloading mechanism. Most harvesters developed so far adopted a sort of slide and free falling way in collecting cabbages into the pallet. Three or four labors are usually required for cleaning incoming cabbages and loading those in the pallet. Because of the required time for piling cabbages without severe damage and the required space capacity to carry empty and loaded pallets, harvesting speed should be adjusted in accordance with time required for consecutive operations. Up to now, any automatic or semi-automatic collecting device has not been developed in the world to pile cabbages on the layer one by one into the pallet in the ordered way with little damage and to unload pallet from the harvester continuously during the harvest process. To compromise system expenses and function, Semi-automatic cabbage piling and pallet unloading mechanism was devised and it required one labor. The foldable mesh pallet with a size of 1050mm x 1050mm x 1000mm and holding capacity of around 70 cabbages was utilized. The prototype for piling and unloading mechanism was composed of three parts such as feeding device, automatic piling device with retractable bellows, and pallet unloading device. Prior to developing the prototype, the geometric properties and the amount of the damage of the cabbage caused during the piling operation were investigated. Considering the height of the pallet, a series of cabbage carrying plates were mounted to the bracket chain to lift and to carry cabbages to the loading device. Indoor laboratory experiments showed that the cabbage carrying chain conveyor worked successfully. Considering the conveying speed 0.46m/sec of the pull up belt from the cabbages on the ground, the speed of cabbage carrying chain conveyor worked property in the range of 0.26m/sec to 0.36m/sec. The system allowed the operator to modify the position of cabbage slightly. Overall system worked successfully resulting into almost same capacity without severe damage to the cabbage as human did.

• Proceedings of the KWS Conference
• /
• 2009.11a
• /
• pp.45-45
• /
• 2009

원가 측면에서 유리한 저항점용접(Resistance Spot Welding)이 차체 용접에 80%이상으로 가장 많이 적용되고 있다. 첨단고강도강(Advanced High Strength Steel)의 저항점용접성 및 용접부 특성에 미치는 공정 변수의 영향에 대한 연구결과는 많으나, 합금원소의 영향에 대해서는 전무하다. 특히, Si는 DP(Dual Phase)강에 첨가 시 균일한 마르텐사이트의 분포를 촉진하는 원소로 저항 점용접성 및 용접부 특성에 영향을 미칠 것으로 예상되며, 이에 대한 연구는 보고된바 없다. 본 연구에서는 냉연 DP강의 저항 점용접시 중요한 인자 중 하나인 너깃경과 전단인장강도에 미치는 Si함유량의 영향을 검토하였다. 사용된 강재 및 용접기는 1.2mm 두께의 Si함유량(0, 0.5, 1.0, 1.5wt%)이 다른 인장강도 780~1000MPa급 냉연 DP강과 단상 AC용접기를 사용하였다. 용접조건은 ISO 18278-2규격에 따라 가압력 4kA, 초기가압시간 40cycle, 유지시간 17cycle로 고정하고, 용접전류만 변화하여 용접을 실시하였다. 너깃경은 용접부 단면을 컷팅 후 폴리싱 하여, 광학현미경과 Image Pro plus를 이용하여 측정했으며, 인장시편규격은 JIS Z 3137를 이용하였다. Si함유량이 증가에 따라 스패터 발생 전류는 감소했고, 너깃경은 직선적으로 증가했다. Si함유량 증가에 따른 너깃경 증가 이유는 저항(R) 측정결과, Si함유량 증가에 따라 모재의 저항이 높아져, 따라서 입열량($Q=I^2Rt$)이 많아지기 때문으로 판단되었다. 인정전단강도는 Si함유량 증가에 따라 직선적으로 증가했다. 이러한 이유는 Si함유량 증가에 따라 너깃경이 증가되기 때문으로 판단되었고, 너깃경과 인장전단강도 사이에 직선적 관계(PL(kN)=$3.2N_{dia.}$-0.81, $R^2$=0.93)를 가지고 있었다. 파단양상은 Si함유량에 상관없이 5.4kA이하에서는 계면파단이 일어났고, 6.0kA이상에서는 풀 아웃 파단이 일어났다. 계면파단주원인은 용접부 가장자리에 지름이 약 $5{\mu}m$이하의 예리한 노치가 존재하여 노치응력집중과 HAZ계면 근처에 미접합부가 존재하기 때문으로 판단되었다. 6.0kA이상에서는 예리한 노치가 없었고, HAZ부가 완전히 접합되어 있기 때문에 풀 아웃 파단이 일어난 것으로 판단되었다. 따라서, Si함유량 증가에 따라 적정용접전류 구간은 감소했고, 너깃경은 직선적으로 증가했다. 또한, Si함유량 증가에 따라 인장전간강도는 증가 했으며, 너깃경과 인장전단강도 사이에 직선적 관계를 가지고 있었다. 파단 양상은 Si함유량에 상관없이 5.2kA이하에서는 계면파단이, 6.0kA이상에서는 풀 아웃 파단이 일어났다.

• Economic and Environmental Geology
• /
• v.25 no.1
• /
• pp.61-72
• /
• 1992

The Danyang area consists of the thrust and folded sedimentary rocks of Paleozoic and Mesozoic Era. The area is bounded by major tectonic units which are the Gagdong Thrust to the west and the Okdong Fault to the east. According to the structural analyses, the area is affected by polyphase deformation. This study establishes deformational sequence in the area. Mylonite zone along the Okdong Fault corresponds to the first generation of structures ($D_1$). $D_1$-structures are discrete shear zone in the Jangsan Formation and bedding parallel extensional deformation in the Cambro-Ordovician sequences. $D_2$-structures were formed prior to the sedimentation of the Jurassic Bansong Group, which are the NW-trending fold and linear structures. After sedimentation of the Bansong Group, the area is strongly affected by the Daebo Orogeny which produces NE-trending thrusts, folds and linear structures. Earlier structures were tightened and rotated toward NE. Some thrust faults did not propagate into the Bansong Group. It is suggested either the Bansong Group acted as a decoupling horizon or rest on unconformably on the thrust faults. The area is weakly affected by $D_4$-event of which structures are E-W trending folds and faults. The Jugryeong Fault clearly cut the earlier folds and thrust faults. The rocks within the fault zone were sliced and rotated during the strike-slip movements. Block rotation and transpressional features can be commonly observed.

• Economic and Environmental Geology
• /
• v.51 no.3
• /
• pp.233-248
• /
• 2018

Strata of the Central sub-basin in the Gunsan Basin, offshore, western Korea were analyzed by using integrated stratigraphy approach. As a result, five distinct unconformity-bounded units are recognized in the basin: Sequence I (Cretaceous or older(?)), Sequence II (Late Cretaceous), Sequence III (late Late Cretaceous or younger(?)), Sequence IV (Early Miocene or older(?)), Sequence V (Middle Miocene). Since the late Late Jurassic, along the Tan-Lu fault system wrench faults were developed and caused a series of small-scale strike-slip extensional basins. The sinistral movement of wrench faults continued until the Late Cretaceous forming a large-scale pull-apart basin. However, in the Early Tertiary, the orogenic event, called the Himalayan Orogeny, caused basin to be modified. From Late Eocene to Early Miocene, tectonic inversion accompanied by NW strike folds occurred in the East China. Therefore, the late Eocene to Oligocene was the main period of severe tectonic modification of the basin and Oligocene formation is hiatus. The rate of tectonic movements in Gunsan Basin slowed considerably. In that case, thermal subsidence up to the present has maintained with marine transgressions, which enable this area to change into the land part of the present basin.