• Journal of the Korean Society for Precision Engineering
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• v.31 no.7
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• pp.561-567
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• 2014

Precision injection mold is an essential element in order to manufacture small and precision plastic lenses used for phone camera. There are many critical factors to meet the requested specifications of high quality plastic lenses. One of the main issues to realize high quality is minimizing decenter value, which becomes more critical as pixel numbers increases. This study suggests the method to minimize decenter value by modifying ejecting structure of the mold. Decenter value of injection-molded lens decreased to 1 ${\mu}m$ level from 5 ${\mu}m$ by applying suggested ejecting method. Also, we also developed BIS (Built-in Sensor) based smart mold system, which has pressure and temperature sensors inside of the mold. Pressure and temperature profiles from cavities are obtained and can be used for deduction of optimal injection molding condition, filling imbalance evaluation, status monitoring of injection molding and prediction of lens quality.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.4 s.247
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• pp.465-472
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• 2006

Recently, the regulations of the government and the concerns of people have rise to the interest in noise pollution levels as compared to other vehicles. In this area, many researchers have studied to reduce this noise in the field of automotive engineering. This paper proposes an optimal design scheme to reduce the noise of the intake system by adapting Kriging with two meta-heuristic techniques. For this, as a measuring tool for the performance of the intake system, the performance prediction software, was used. Then, the length and radius of each component of the current intake system are selected as input variables and the orthogonal arrays is adapted as a space-filling design. With these simulated data, we can estimate a correlation parameter in Kriging by solving the nonlinear problem with a genetic algorithm and find an optimal level for the intake system by optimizing Kriging estimated with simulated annealing. We notice that this optimal design scheme gives noticeable results and is a preferable way to analyze the intake system. Therefore, an optimal design for the intake system is proposed by reducing the noise of its system.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.57-64
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• 2010

Metal Injection Molding (MIM) is attractive because it produces consistent, complex-geometry components for high-volume, high-strength, and high-performance applications. Also MIM using in optical communication field, display field, and semi-conductor field is a cost-effective alternative to metal machining or investment casting parts. It offers tremendous single-step parts consolidation potential and design flexibility. The objective of this paper is to study the suitability of design, flow analysis, debinding and sinterin processes, and capability analysis. The suitable injection conditions were 0.5~1.5 second filling time, 11.0~12.5 MPa injection pressure derived from flow analysis. The gravity of the product is measured after debinding an sintering. The maximum and minimum gravity levels are 7.5939 and 7.5097. the average and standard deviation are 7.5579 and 0.0122; when converted into density, the figure stands at 98.154%. According to an analysis of overall capacity, PPM total, which refers to defect per million opportunities(DPMO), stands at 166,066.3 Z.Bench-the sum of defect rates exceeding the actual lowest and highest limits-is 0.97, which translates into the good quality rate of around 88.4% and the sigma level of 2.47.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.11
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• pp.121-126
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• 1972

Regim-8(TIBA), a Chemical pinching agent, was applied to soybean plants of 6 varieties at 6 leaf stage in oder to develop a chemical pruning method. The results are summarized as follows: 1) The more inhibition in plant height and rare lodging were abserved at 2, 000ppm level of treatment (50cc of Regim-8 diluted in 100ι of water). 2) Number of branches and grains per plant were increased by Regim-8 treatment, while number of main stem nodes were decreased. 3) It appeared that photosynthetic efficiency of the soybean plant community treated by Regin-8 were improved. This increased number of pod per plant and hence soybean yield increased by applying Regim-8. 4) Antilodging effects of Regim-8 were also appeared to result in better filling of pods and higher yield per unit area.

• Culinary science and hospitality research
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• v.13 no.1 s.32
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• pp.152-165
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• 2007

The purpose of this study is to prove that the appropriate fit between service failure and recovery strategy can efficiently maximize customer satisfaction and behavioral intention, by using the prepared scenario through comprehensive approach concerning how the expectation level of service recovery has influence on perceived fairness, satisfaction and behavioral intention of service recovery based upon size in case of service failure. This study has been conducted by way of selection of filling-up type questionnaires for customers themselves who have experience in service failure out of customers who can easily visit family and hotel restaurants, that is, domestic restaurants in Seoul area, $June{\sim}August$ 2004, by setting factorial design of 2(control, severeness)$\times$3(distributive fairness, procedural fairness, mutual relational fairness)$\times$2(customer satisfaction, customer behavior). The survey was performed on the customers who visited common restaurants, family restaurants, hotel restaurants, etc. mainly in Seoul, and total 600 sheets of questionnaires were distributed and 496 sheets of them were returned(82.67% of return ratio). Research findings are as follows; First, perceived recovery justice has an effect on customer satisfaction and behavioral intention. Second, customer satisfaction and restaurant satisfaction have positive influence on behavioral intention. The results will be helpful for them to develop a further service failure and recovery framework. For service marketing managers, the results will suggest specific guidelines for establishing service recovery strategies.

• Korean Journal of Health Education and Promotion
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• v.24 no.4
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• pp.149-159
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• 2007

This study was intended to provide basic data for developing an oral health management program for diabetic patients by understanding their oral health condition and defining the influence of diabetes on oral health. The following results were obtained through intraoral examination and questionnaire surveys done on one hundred and twenty two diabetic outpatients who visited endocrine department at Yeungnam University in Daegu and internal medicine department at Chungmu hospital in Cheonahn for 4 months from November, 2005 to February, 2006. DMF index according to the gender was significantly higher in females only in Filling index (p <0.05). Missing index increased as the age increased (p <0.001). Papillary bleeding index was significantly higher in females (p <0.05). Several indices which show oral status significantly higher as the duration of diabetes increased and as the blood sugar level before meal was higher (p <0.01, p <0.05). In a group that received oral hygiene education, several indices which show periodontal status were significantly lower than those in a group that didn't have it (p <0.001). According to the results, not only diabetic control but also general oral care should be included in self-management education for diabetic patients and this should be accomplished by appropriate oral health education program and staffs.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.2
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• pp.88-92
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• 2000

Excessive soil water in paddy field induces growth losses during the vegetative stages of soybean plants. Our objectives were to know growth responses of soybean as affected by the level of ridge heights. A field experiment was conducted at the Research Farm of Korea University near Seoul in 1996. Ten cultivars of soybean (Glycine max (L.) Merrill) were planted at the ridge heights of 10, 30, and 50cm in paddy soil on 27 June. Total dry matter accumulation at the 10cm ridge height was severely decreased until the growth stage of R5 as compared to the ridge heights of 30 and 50cm, and this decrement was mainly due to both reduced leaf and stem dry weights. However, seed dry weight was not significantly decreased at the lower ridge height with the increment of harvest index. Cultivar differences were found on seed dry weight, crop growth rate from R1 to R5, and leaf/stem ratio of R5. From the above results, soybean growth responses to excessive soil water in paddy field were different between seed filling stage and late vegetative to early reproductive growth stages.

• Nuclear Engineering and Technology
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• v.38 no.1
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• pp.99-108
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• 2006

SNU-RCCS is a water pool type RCCS (Reactor Cavity Cooling System) developed for VHTR (Very High Temperature Reactor) application by SNU (Seoul National University). Since radiation heat transfer is the major process of passive heat removal in a RCCS, it is important to determine the precise emissivity of the reactor vessel. Review studies have used a constant emissivity in the passive heat removal analysis, even though the emissivity depends on many factors such as temperature, surface roughness, oxidation level, wavelength, direction, atmosphere conditions, etc. Therefore, information on the emissivity of a given material in a real RCCS is essential in order to properly analyze the radiation heat transfer in a VHTR. The objectives of this study are to develop a method for compensation of the factors affecting the emissivity measurement using an infrared thermometer and to estimate the true emissivity from the measured emissivity via the developed method, especially in the SNU-RCCS environment. From this viewpoint, we investigated factors such as the attenuation effect of the window, filling gas, and the effect of background radiation on the emissivity measurements. The emissivity of the vessel surface of the SNU-RCCS facility was then measured using a sight tube. The background radiation was subsequently removed from the measured emissivity by solving a simultaneous equation. Finally, the calculated emissivity was compared with the measured emissivity in a separate emissivity measurement device, yielding good agreement with the emissivity increase with vessel temperature in a range of 0.82 to 0.88.

• Journal of the Korean School Mathematics Society
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• v.12 no.4
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• pp.453-472
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• 2009

This article describes the interview data with two preservice teachers where they dealt with five water-filling problems for the investigation of their covariational thinking. The study's results revealed that two students developed their covariation levels from Direction level to Instantaneous Rate with an aid of the pre-constructed GSP simulations for the problem situations. However, this study also points out that there is a missing important feature for a function notion, 'causality' in the covariation framework and suggests that future research should combine students' conception of causality with their covariational thinking for the investigation of their development of a function concept.

• Journal of Korean Neurosurgical Society
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• v.49 no.5
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• pp.287-289
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• 2011

Thalamoperforating artery aneurysms are rarely reported in the literature. We report an extremely rare case of ruptured distal anterior thalamoperforating artery aneurysm which was treated by endovascular obliteration in a patient with occlusion of both the internal carotid arteries (ICAs) : A 72-year-old woman presented with severe headache and loss of consciousness. Initial level of consciousness at the time of admission was drowsy and the Glasgow Coma Scale score was 14. Brain computed tomography (CT) scan was performed which revealed intracerebral hemorrhage in right basal ganglia, subarachnoid hemorrhage, and intraventricular hemorrhage. The location of the aneurysm was identified as within the globus pallidus on CT angiogram. Conventional cerebral angiogram demonstrated occlusion of both the ICAs just distal to the fetal type of posterior communicating artery and the aneurysm was arising from right anterior thalamoperforating artery (ATPA). A microcatheter was navigated into ATPA and the ATPA proximal to aneurysm was embolized with 20% glue. Post-procedural ICA angiogram demonstrated no contrast filling of the aneurysm sac. The patient was discharged without any neurologic deficit. Endovascular treatment of ATPA aneurysm is probably a more feasible and safe treatment modality than surgical clipping because of the deep seated location of aneurysm and the possibility of brain retraction injury during surgical operation.