• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.10a
• /
• pp.686-686
• /
• 2013

Automotive turbochargers have become common in gasoline engines as well as diesel engines. They are excellent devices to effectively increase fuel efficiency and power of the engines, but they unfortunately cause several noise problems. The noises are classified into mechanical noises induced from movement of a rotating shaft and aerodynamic noises by air flow in turbochargers. In addition to, there is a mechanical noise caused from movement of an actuator, electronically controlling a wastegate valve. It is called as valve rattle noise. The actuator is connected to a valve through a linkage. The noise occurs only if the valve is open, where the linkage is freely contact to neighbor structures without being constrained by any external forces. This condition allows impacts by the pulsation of exhaust gas, and the vibration from the impacts spreads out through turbine housing, causing the rattle noise. The noise is not in mechanical operating wastegate turbochargers because the linkage of an actuator is strongly connected by actuating force. For the electronic wastegate turbocharger, this paper proposed a test device to show the noise generating mechanism with a small vibration motor having an unbalanced shaft. It also shows how to reduce the noise - reduction of linkage clearances, inserting wave washers into a connection, and applying loose fitting in bushing embracing a valve lever to turbine housing.

• Journal of Internet Computing and Services
• /
• v.16 no.5
• /
• pp.19-27
• /
• 2015

Due to the advantages of fast read/write operation and low power consumption, SSD(Solid State Drive) is now widely adopted as storage device of smart phone, laptop computer, server, etc. However, the shortcomings of SSD such as limited number of write operations and asymmetric read/write operation lead to the problem of shortened life span of SSD. Therefore, the block replacement policy of SSD used as cache for HDD is very important. The existing solutions for improving the lifespan of SSD including the LARC scheme typically employ the LRU algorithm to manage the SSD blocks, which may increase the miss rate in SSD due to the replacement of frequently used block instead of rarely used block. In this paper we propose a novel block replacement scheme which considers the block reuse interval to effectively handle various data read/write patterns. The proposed scheme replaces the block in SSD based on the recency decided by reuse interval and age along with hit ratio. Computer simulation using workload trace files reveals that the proposed scheme consistently improves the performance and lifespan of SSD by increasing the hit ratio and decreasing the number of write operations compared to the existing schemes including LARC.

• Journal of Internet Computing and Services
• /
• v.15 no.2
• /
• pp.19-31
• /
• 2014

In this paper, a parallel backoff delay procedure on multiple IEEE 802.15.4 channels and a channel searching method considering the frequency spectrum of WiFi traffic are studied for IEEE 802.15.4 nodes to avoid the interference from WiFi traffic. In order to search the channels being occupied by WiFi traffic, we analyzed the methods measuring the powers of adjacent channels simultaneously, checking the duration of measured power levels greater than a threshold, and finding the same periodicity of sampled RSSI data as the beacon frame by signal processing. In an wireless channel overlapped with IEEE 802.11 network, the operation of CSMA-CA algorithm for IEEE 802.15.4 nodes is explained. A method to execute a parallel backoff procedure on multiples IEEE 802.15.4 channels by an IEEE 802.15.4 device is proposed with the description of its algorithm. When we analyze the data measured by the experimental system implemented with the proposed method, it is observed that medium access delay times increase at the same time in the associated IEEE 802.15.4 channels that are adjacent each other during the generation of WiFi traffic. A channel evaluation function to decide the interference from other traffic on an IEEE 802.15.4 channel is defined. A channel searching method considering the channel evaluations on the adjacent channels together is proposed in order to search the IEEE 802.15.4 channels interfered by WiFi, and the experimental results show that it correctly finds the channels interfered by WiFi traffic.

• Applied Chemistry for Engineering
• /
• v.25 no.1
• /
• pp.1-13
• /
• 2014

Lithium ion batteries (LIBs) are the state-of-the-art technology among electrochemical energy storage and conversion cells, and are still considered the most attractive class of battery in the future due to their high specific energy density, high efficiency, and long cycle life. Rapid development of power-hungry commercial electronics and large-scale energy storage applications (e.g. off-peak electrical energy storage), however, requires novel anode materials that have higher energy densities to replace conventional graphite electrodes. Germanium (Ge) and silicon (Si) are thought to be ideal prospect candidates for next generation LIB anodes due to their extremely high theoretical energy capacities. For instance, Ge offers relatively lower volume change during cycling, better Li insertion/extraction kinetics, and higher electronic conductivity than Si. In this focused review, we briefly describe the basic concepts of LIBs and then look at the characteristics of ideal anode materials that can provide greatly improved electrochemical performance, including high capacity, better cycling behavior, and rate capability. We then discuss how, in the future, Ge anode materials (Ge and Ge oxides, Ge-carbon composites, and other Ge-based composites) could increase the capacity of today's Li batteries. In recent years, considerable efforts have been made to fulfill the requirements of excellent anode materials, especially using these materials at the nanoscale. This article shall serve as a handy reference, as well as starting point, for future research related to high capacity LIB anodes, especially based on semiconductor Ge and Si.

• Korean Journal of Food Science and Technology
• /
• v.23 no.3
• /
• pp.341-348
• /
• 1991

Physicochemical properties and gelatinization patterns of defatted and lipid-reintroduced moist (Hwangmi) and dry (Suwon 147) type sweet potato starches were investigated. Starch granules of sweet potato were polygonal and round, and the sizes of starch granules ranged $5{\sim}13\;{\mu}m$. All starches showed Ca type in X-ray diffraction but relative crystallinity was decreased by defatting and reintroduction. The amylose content of defatted starches increased, but that of lipid-reintroduced starches decreased. The swelling power and solubility at each temperature increased by defatting, but decreased by reintroduction. Transmittance of Hwangmi and Suwon 147 showed a rapid increase at $60,\;65^{\circ}C$, respectively. The initial pasting temperature by amylograph of Hwangmi and Suwon 147 were $67.5^{\circ}C\;and\;72.7^{\circ}C$, respectively. The peak viscosity and the height at $50^{\circ}C$ on amylogram of Hwangmi were lower than those of Suwon 147. Hot paste viscosity and setback decreased by defatting but setbak and consistency drastically increased by reintroduction. The peak temperature for gelatinization by the DSC was $65.7^{\circ}C$ for Hwangmi and $68.5^{\circ}C$ for Suwon 147. The gelatinization temperature and enthalpy of the DSC decreased and amylose-lipid melting peak was lost by defatting. The gelatinization temperature and enthalpy decreased by reintroduction.

• Korean Journal of Food Science and Technology
• /
• v.52 no.2
• /
• pp.156-161
• /
• 2020

This study was designed to evaluate the quality characteristics and antioxidant activities of noodles containing Allium senescens L. powder (0, 2, 4, 6, and 8%). With an increase in the consumption of Allium senescens L., there was a decrease in pH (p<0.001), water absorption ratio, volume expansion ratio, and turbidity (p<0.05). The colorvalue showed that the addition of Allium senescens L. decreased the L and b values. On the other hand, a value was increased (p<0.001). The mechanical texture of the noodles containing Allium senescens L. was decreased by the addition of Allium senescens L. considering its hardness and chewiness; however, it increased the adhesiveness, springiness, and cohesiveness (p<0.001). In the sensory evaluation, the noodles with 4% Allium senescens L. powder showed the best results (p<0.001). The total polyphenol content, total flavonoid content, DPPH radical scavenging, and reducing power were increased upon addition of Allium senescens L. powder (p<0.001).

• The Korean Journal of Health Service Management
• /
• v.3 no.1
• /
• pp.14-24
• /
• 2009

This study aims at deriving any useful information necessary to strengthen the competitiveness for growth through empirical analyses on general hospital located in a province in order to countermeasure the opening and competition of medical markets. The characteristics of user were identified on the basis of disease groups under KCD in the research method. In addition, the analysis on the expenses of diagnosis and treatment was divided into the treatment progress and degree of hospital resource utilization And the regression was carried out to identify the impacts of characteristics of inpatient users on the degree of hospital resource utilization. As a result of major research, the inpatient users of the general hospital located in the provincial area in consideration of inpatient users were formed around the inpatient disease groups representative for Korea(diseases of the respiratory system, injury and poisoning & certain other consequences of external causes). And it was understood that most of residents within a distance of 40 minute by the public transportation were using. And mostly were under the age of 9 or over 60, and the provision of medical features such as the degree of consultation and operational functions were inadequate. When we classify inpatient treatment cost for each resource application as the medical cost being the center of patient care function, the equipment and human resource application sector are constituted over half. Accordingly, the following suggestions are made as plans to strengthen the competitiveness for the growth of general hospitals located in the provincial areas on the basis of analytical results. First, it is necessary to have the characterization matching to the age and disease groups with a high frequency. Second, it is necessary to increase the degree of hospital resource utilization according to the characterization. Third, it is necessary to concentrate on public relations. The above suggestion, as a method for securing image improvement and competitive power as a general hospital, and through expansion of social function that a regional general hospital needs to secure not only as an individual institution but also as a general hospital, it can be seen that a general improvement of image as a regional general hospital is possible.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.9
• /
• pp.196-205
• /
• 2016

The exhaust gas discharged by cars not only threatens the health of the human body, but also contributes to global warming, due to the resulting increase in the concentrations of ozone, fine dust and carbon dioxide. Therefore, the government has steadily implemented careful inspection systems for exhaust emissions, in order to efficiently regulate the exhaust gas of cars. Studies on reducing the exhaust emissions of automobiles have been conducted in various fields, including ones designed to reduce the generation of HC, NOx, and $CO_2$ in the exhaust emission of vehicles. However, there have been insufficient studies on the reduction of the exhaust emission for old diesel vehicles. To develop careful inspection systems for the exhaust emissions of old diesel vehicles, studies on the reduction of the exhaust emissions and improvement of power are necessary by cleaning the carbon sediment in both the intake manifold and injector. Therefore, in this study, we analyzed and compared the amounts of gas emitted when simultaneously cleaning or not cleaning the intake manifold and injector of diesel automobiles with mileages over 80,000 km and operating periods over 5 years. The experimental results showed that in the case where the intake manifold and injector were simultaneously cleaned, there was a decline of 75.2% in the gas emission compared to the cases where only the manifold or injector is cleaned. Also, it was found that simultaneously cleansing the intake manifold and injector enabled the exhaust standard to be satisfied for less than 30% within 8.5 sec.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.4
• /
• pp.143-153
• /
• 2017

This was a descriptive survey to determine the intention of users to use smartphone healthcare applications (SHAs) and to clarify factors that may influence such intention. The data were collected during the month of April in 2015, using a structured self-report questionnaire that was distributed to 300 participants aged 20 to 70 years; 285 complete copies were used for the final analysis. The data were analyzed using descriptive statistics, independent t-test, one-way ANOVA, Pearson correlation coefficients, and hierarchical multiple regression. First, according to the results, the average intention to use SHAs was 3.28 out of 5, which varied according to age, final education, economy level, vacation, current disease, total period of smartphone use, and etc. Second, significant correlations were shown by exercise behavior, dietary management behavior, stress management, satisfaction with smartphone use, and satisfaction with using SHAs. Third, the explanatory power of the predictive model involving all general, health-related, smartphone use-related, and SHA use-related factors was 45.5%; and the economic level, interest, status, and awareness satisfaction of patients using SHA were identified to be the main influential factors. The results indicate that SHA developers need to put efforts into improving consumers' app recognition and to develop plans in provoking consumers' interests to increase the use of SHAs.

• Current Research on Agriculture and Life Sciences
• /
• v.22
• /
• pp.19-27
• /
• 2004

Cultivation area of garlics is 9% of all cultivation area of vegetables. The amount of annual demand is increased in 1,000~1,500ton. Also, the amount of demand per person has a tendency to increase as above 10kg. So, garlics has become important crops in agriculture. The purpose of this study is to acquire the basic information to design the garlic seeder attached power tiller. We used Working Model 3D program to design an automatic aligning device which is the most important part of the garlic seeder. The results are as follows; 1. The optimum depth of garlics seeding was shown as 3cm. 2. The garlic seed has to he discharged from the garlic seeder at intervals of 0.75sec in order to seed at intervals of seeds of 15cm. 3. The optimum design factors of the automatic aligning device were shown as cylinder diameter of 4cm, cylinder gap of 1cm, revolution of 36rpm and inclined angle of cylinder of $8.4^{\circ}$.