• The Journal of the Acoustical Society of Korea
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• v.28 no.3
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• pp.229-238
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• 2009

This paper describes a sound engine of Korean traditional instruments, which are the Gayageum and Taepyeongso, by using a TMS320F2812. The Gayageum and Taepyeongso models based on commuted waveguide synthesis (CWS) are required to synthesize each sound. There is an instrument selection button to choose one of instruments in the proposed sound engine, and thus a corresponding sound is produced by the relative model at every certain time. Every synthesized sound sample is transmitted to a DAC (TLV5638) using SPI communication, and it is played through a speaker via an audio interface. The length of the delay line determines a fundamental frequency of a desired sound. In order to determine the length of the delay line, it is needed that the time for synthesizing a sound sample should be checked by using a GPIO. It takes $28.6{\mu}s$ for the Gayageum and $21{\mu}s$ for the Taepyeongso, respectively. It happens that each sound sample is synthesized and transferred to the DAC in an interrupt service routine (ISR) of the proposed sound engine. A timer of the TMS320F2812 has four events for generating interrupts. In this paper, the interrupt is happened by using the period matching event of it, and the ISR is called whenever the interrupt happens, $60{\mu}s$. Compared to original sounds with their spectra, the results are good enough to represent timbres of instruments except 'Mu, Hwang, Tae, Joong' of the Taepyeongso. Moreover, only one sound is produced when playing the Taepyeongso and it takes $21{\mu}s$ for the real-time playing. In the case of the Gayageum, players usually use their two fingers (thumb and middle finger or thumb and index finger), so it takes $57.2{\mu}s$ for the real-time playing.

• Korean Journal of Radiology
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• v.23 no.1
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• pp.68-76
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• 2022

Objective: Percutaneous portal vein (PV) stent placement can be an effective treatment for symptoms associated with portal hypertension. This study aimed to evaluate the effect of PV stenting on the overall survival (OS) in patients with malignant PV stenosis. Materials and Methods: Two groups of patients with malignant PV stenosis were compared in this retrospective study involving two institutions. A total of 197 patients who underwent PV stenting between November 2016 and August 2019 were established as the stent group, whereas 29 patients with PV stenosis who were treated conservatively between July 2013 and October 2016 constituted the no-stent group. OS was compared between the two groups before and after propensity score matching (PSM). Risk factors associated with OS were evaluated using the Cox proportional hazards model. Procedure-associated adverse events were also evaluated. Results: The stent group finally included 100 patients (median age, 65 [interquartile range, 58-71] years; 64 male). The no-stent group included 22 patients (69 [61-75] years, 13 male). Stent placement was successful in 95% of attempted cases, and the 1- and 2-year stent occlusion-free survival rate was 56% (95% confidence interval, 45%-69%) and 44% (32%-60%), respectively. The median stent occlusion-free survival time was 176 (interquartile range, 70-440) days. OS was significantly longer in the stent group than in the no-stent group (median 294 vs. 87 days, p < 0.001 before PSM, p = 0.011 after PSM). The 1- and 3-year OS rates before PSM were 40% and 11%, respectively, in the stent group. The 1-year OS rate after PSM was 32% and 5% in the stent and no-stent groups, respectively. Anemia requiring transfusion (n = 2) and acute thrombosis necessitating re-stenting (n = 1) occurred in three patients in the stent group within 1 week. Conclusion: Percutaneous placement of a PV stent may be effective in improving OS in patients with malignant PV stenosis.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.3
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• pp.121-129
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• 2024

The rapid advancement of digital technology and the COVID-19 pandemic have significantly accelerated the growth of online commerce, highlighting the need for support mechanisms that enable small business owners to effectively respond to these market changes. In response, this paper presents a foundational technology leveraging the Online to Offline (O2O) strategy to automatically capture products displayed on retail shelves and utilize these images to create virtual stores. The essence of this research lies in precisely identifying and recognizing the location and names of displayed products, for which a single-class-targeted, lightweight model based on YOLOv8, named ESD-YOLOv8, is proposed. The detected products are identified by their names through feature-point-based technology, equipped with the capability to swiftly update the system by simply adding photos of new products. Through experiments, product name recognition demonstrated an accuracy of 74.0%, and position detection achieved a performance with an F2-Score of 92.8% using only 0.3M parameters. These results confirm that the proposed method possesses high performance and optimized efficiency.

• Information Systems Review
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• v.26 no.1
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• pp.73-91
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• 2024

Recently, e-learning platforms are rapidly growing by innovating the education industry by applying various IT technologies. Because student participation in the online environment is considered a prerequisite for learning, low participation rates are considered one of the most important issues determining the performance of e-learning platforms. Gamification has grown rapidly over the past decades and is highly valued for its applicability in education because it is expected to enhance learning motivation. However, despite the interest of researchers, previous studies have reported conflicting results on the effect of gamification on participation rates in the context of e-learning platforms, and have mainly studied structural gamification, but have not sufficiently addressed the effects of content gamification. In this context, this study aims to analyze the effect of content gamification on e-learning platform engagement and to explore the boundary conditions moderating this effect. For empirical analysis, 5,017 data registered from February 11, 2022 to May 31, 2022 were analyzed for the education platform entry (https://playentry.org). The propensity score matching method and Poisson multilevel regression model were applied as analysis methods. As a result of the analysis, content gamification had a statistically significant effect on engagement, and the interaction effects of interaction and content difficulty were statistically significant.

• Investigative Magnetic Resonance Imaging
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• v.18 no.2
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• pp.107-119
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• 2014

Purpose : To efficiently evaluate phased array coil performance using a software tool box with which we can make visual comparison of the sensitivity of every coil element between the real experiment and EM simulation. Materials and Methods: We have developed a $C^{{+}{+}}$- and MATLAB-based software tool called Phased Array Coil Evaluator (PACE). PACE has the following functions: Building 3D models of the coil elements, importing the FDTD simulation results, and visualizing the coil sensitivity of each coil element on the ordinary Cartesian coordinate and the relative coil position coordinate. To build a 3D model of the phased array coil, we used an electromagnetic 3D tracker in a stylus form. After making the 3D model, we imported the 3D model into the FDTD electromagnetic field simulation tool. Results: An accurate comparison between the coil sensitivity simulation and real experiment on the tool box platform has been made through fine matching of the simulation and real experiment with aids of the 3D tracker. In the simulation and experiment, we used a 36-channel helmet-style phased array coil. At the 3D MRI data acquisition using the spoiled gradient echo sequence, we used the uniform cylindrical phantom that had the same geometry as the one in the FDTD simulation. In the tool box, we can conveniently choose the coil element of interest and we can compare the coil sensitivities element-by-element of the phased array coil. Conclusion: We expect the tool box can be greatly used for developing phased array coils of new geometry or for periodic maintenance of phased array coils in a more accurate and consistent manner.

• The Journal of Korean Academy of Sensory Integration
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• v.21 no.2
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• pp.45-57
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• 2023

Objective : The purpose of this study was to investigate the concurrent validity of the self- and proxy-report versions of the KIDSCREEN-10 quality of life questionnaire. Methods : A total of nine children and nine parents were selected to represent a cohort registered for a school-based wellness program. Two versions of the KIDSCREEN-10 questionnaire (self- and proxy reports) were administered to the children and their parents. The Rasch rating scale model was applied to determine the dimensionality and item difficulty of the two versions of the questionnaire. Moreover, the item-person matching map and Spearman's rho were compared to confirm the concurrent validity of the two versions. Results : All items, except four items (i.e., autonomy, home life, concentration/learning, and peers/social support), fit the Rasch rating scale model of the children's self-report version of the questionnaire. With regard to the parent's proxy-report version, two items misfit the model. While the items of the self- and proxy-report versions showed similar item difficulties, the parents had a tendency to be more severe in their ratings than the children. The correlation between the two versions was relatively low (Spearman's rho = .533, p > .05). The scatterplots between the two versions showed differences in the item difficulties of the physical and psychological well-being and self-perception items. Conclusion : These findings suggest that the three identified items should be taken into consideration when measuring children's health-related quality of life using the KIDSCREEN-10 questionnaire.

• Journal of Preventive Medicine and Public Health
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• v.35 no.3
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• pp.245-254
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• 2002

Objective : To test if the intake of $H_2$ receptor antagonists ($H_2$-RAs) increases the risk of gastric cancer in the elderly. Methods : The source population for this study was drawn from the responders to a questionnaire survey administered to the Korea Elderly Pharmacoepidemiological Cohort (KEPEC), who were beneficiaries of the Korean Medical Insurance Corporation, were at least 65 years old, and residing in Busan in 1999. The information on $H_2$-RAs exposure was obtained from a drug prescription database compiled between inn. 1993 and Dec. 1994. The cases consisted of 76 gastric cancer patients, as confirmed from the KMIC claims data, the National Cancer Registry and the Busan Cancer Registry. The follow-up period was from Jan. 1993 to Dec. 1998. Cancer free controls were randomly selected by 1:4 individual matching, which took in to consideration the year of birth and gender. Information on confounders was collected by a mail questionnaire survey. The odds ratios, and their 95% confidence intervals, were calculated using a conditional logistic regression model. Results : After adjusting for a history of gastric ulcer symptoms, medication history, and body mass index, the adjusted OR (aOR) was 4.6 (95% CI=1.72-12.49). The odds ratio of long term use (more than 7 days) was 2.3 (95% CI=1.07-4.82). The odds ratio of short term use was 4.6 (95% CI=1.26-16.50). The odds ratio of parenteral use was 4.4 195% CI=1.16-17.05) and combination use between the oral and parenteral routes (aOR, 16.8; 95% CI=1.21-233.24) had the high risk of gastric cancer. The aOR of cimetidine was 1.7 (95% CI=1.04-2.95). The aOR of ranitidine was 2.0 (95% CI=1.21-3.40). The aOR of famotidine was 1.7 (95% CI=0.98-2.80). Conclusion : The intake of $H_2$-RAs might increase the risk of gastric cancer through achlorhydria in the elderly.

• Journal of Korean Society of Transportation
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• v.23 no.1
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• pp.93-102
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• 2005

An Origin-Destination (O/D) is considered as one of the important information in route choices and trip assignments. A household interview survey is deemed to be the traditional and the most widely used method in making sample O/D and its conversion to the total O/D. Some researchers have studied to estimate dynamic O/D from the relationship between link volumes and trip assignment model. Nowadays, owing to the recent rapid spread of cellular phones. Location information of the cellular phone through the Base Station(BS) is considered as an alternative to O/D estimation. In this study, the methodology of generating BS-based O/D and the methodology of converting this O/D into an administrative district-based O/D are proposed. The information of GPS positions and cellular BS positions have acquired by establishing GPS equipment and cellular phone on taxies in Cheongju. Three weeks data are collected and used in estimating O/D by matching them on a digital map. Scatter diagram and sample correlation coefficients are used to investigate the similarity of the GPS-based O/D pattern among weeks, among days, and among times in day. The results show that there are few significant differences among weeks. But there is a difference in O/C pattern between weekday and weekend. Furthermore, there is a difference between morning peak and afternoon peak. Two methodologies are proposed to convert BS-based O/D into an administrative district-based O/D. The first one is to use the distribution pattern of GPS coordinates, the other is to use the coverage area of the BSs. To validate such converted O/D, GPS O/D is used as a true value. The statical analyses through scatter diagram, MAE and RMSE shows that there is few significant defference of pattern between the estimated BS-based O/D and GPS O/D. In the case of using only cellular information, the methodology using coverage area of the BSs is recommended for estimating O/D.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.5
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• pp.67-80
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• 2022

This study was conducted to derive policy measures such as fostering and supporting by examining the actual conditions of domestic startups. The subject of this study was the start-ups located in Seongnam-si, where Pangyo Techno Valley, which is the highest-level innovation cluster in Korea and is evaluated as a start-up mecca. Startups were defined as startups under 7 years old based on new technologies such as IT, BT, and CT, and the subjects of the study were selected. This can be seen as a step forward from previous research in that it embodies the concept of a startup that was previously abstract in a quantitatively measurable way. As a result of the analysis, about 94% of startups are distributed in the so-called "Death Valley" growth stage, and startups above scale-up, which means full-scale growth beyond BEP, account for about 6%. appeared to be occupied. He cited the problem of start-up funds as the biggest difficulty in the early stages of startups, and cited the loan evaluation method that prioritizes sales or collateral in raising funds as the biggest problem. In addition, start-ups rated the access to private investment capital such as VC, AC, and angel investors at a low level compared to policy funds, which are public funds. Most startups showed a lot of interest in overseas expansion, and they chose matching overseas investors such as overseas VCs as the biggest support for overseas expansion. The overall competitiveness in the overseas market was 49.6 points, which is less than 50 points out of 100, indicating that the overall competitiveness was somewhat inferior. It was analyzed that public support and investment in overseas sales channels (sales channels, distribution networks, etc.) should be prioritized along with enhancement of technological competitiveness in order for domestic startups to increase their competitiveness in overseas markets as well as in the domestic market.

• Journal of the Korean association of regional geographers
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• v.3 no.2
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• pp.37-87
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• 1997

As a results of researches on the cultivation processes and settlement developments on the Mangyoung river valley as a whole could be have four 'Space-Time Continuity' through a [Origin-Destination] theory model. On a initial phases of cultivation, the cultivation process has been begun at mountain slopes and tributory plains in upper part of river-basin from Koryo Dynasty to early Chosun Dynasty. At first, indigenous peasants burned forests on the mountain slopes for making 'dryfield' for a cereal crops. Following population increase more stable food supply is necessary facets of life inducing a change production method into a 'wetfield' in tributory plains matching the population increase. First sedentary agriculture maybe initiated at this mountain slopes and tributory plains on upper part of river basin through a burning cultivation methods. Mountain slopes and tributory plains are become a Origin area in cultivation processes. It expanded from up to down through the valleys with 'a bits of land' fashion in a steady pace like a terraced fields expanded with bit by bit of land to downward. They expanded their land to the middle part of river basin in mid period of Chosun Dynasty with dike construction techniques on the river bank. Lower part of river cultivated with embankment building techniques in 1920s and then naturally expanded to the tidal marshes on the estuaries and river inlets of coastal areas. 'Pioneer fringes' are consolidated at there in modern times. Changes in landscapes are appeared it's own characters with each periods of time. Followings are results of study through the Mangyoung river valley as a whole. (1) Mountain slopes and tributory plains on the upper part of river are cultivated 'dryfields' by indigenous peasants with Burning cultivation methods at first and developed sedentary settlements at the edges of mountain slopes and on the river terrace near the fields. They formed a kind of 'periphery-located cluster type' of settlement. This type of settlement are become a prominant type in upper part of river basin. 'Dryfields' has been changed into a 'wetfields' at the narrow tributory plains by increasing population pressure in later time. These wetfields are supplied water by Weir and Ponds Irrigation System(제언수리방법). Streams on the tributory plains has been attracted wetfields besides of it and formed a [water+land] complex on it. 'Wetfields' are expanded from up to downward with a terraced land pattern(adder like pattern, 붕전) according to the gradient of valley. These periphery located settlements are formed a intimate ecological linkage with several sets of surroundings. Inner villages are expanded to Outer villages according to the expansion of arable lands into downward. (2) Mountain slopes and tributory plains expanded its territory to the alluvial deposited plains on the middle part of river valley with a urgent need of new land by population increase. This part of alluvial plains are cultivated mainly in mid period of Chosun Dynasty. Irrigation methods are changed into a Dike Construction Irrigation method(천방수리방법) for the control of floods. It has a trend to change the subjectives of cultivation from community-oriented one who constructed Bochang along tributories making rice paddies to local government authorities who could be gather large sums of capitals, techniques and labours for the big dike construction affairs. Settlements are advanced in the midst of plains avoiding friction of distances and formed a 'Centrallocated cluster type' of settlements. There occured a hierarchical structures of settlements in ranks and sizes according merits of water supply and transportation convenience at the broad plains. Big towns are developed at there. It strengthened a more prominant [water+land] complex along the canals. Ecological linkages between settlements and surroundings are shaded out into a tiny one in this area. (3) It is very necessary to get a modern technology of flood control at the rivers that have a large volume of water and broad width. The alluvial plains are remained in a wilderness phase until a technical level reached a large artificial levee construction ability that could protect the arable land from flood. Until that time on most of alluvial land at the lower part of river are remained a wilderness of overgrown with reeds in lacks of techniques to build a large-scale artificial levee along the riverbank. Cultivation processes are progressed in a large scale one by Japanese agricultural companies with [River Rennovation Project] of central government in 1920s. Large scale artificial levees are constructed along the riverbank. Subjectives of cultivation are changed from Korean peasants to Japanese agricultural companies and Korean peasants fell down as a tenant in a colonial situation of that time in Korea. They could not have any voices in planning of spatial structure and decreased their role in planning. Newly cultivated lands are reflected company's intensions, objectives and perspectives for achieving their goals for the sake of colonial power. Newly cultivated lands are planned into a regular Rectangular Block settings of rice paddies and implanted a large scale Bureaucratic-oriented Irrigation System on the cultivated plains. Every settlements are located in the midst of rice paddies with a Central located Cluster type of settlements. [water+land] complex along the canal system are more strengthened. Cultivated space has a characters of [I-IT] landscapes. (4) Artificial levees are connected into a coastal emnankment for a reclamation of broad tidal marshes on the estuaries and inlets of rivers in the colonial times. Subjectives of reclamation are enlarged into a big agricultural companies that could be acted a role as a big cultivator. After that time on most of reclamation project of tidal marshes are controlled by these agricultural companies formed by mostly Japanese capitalists. Reclaimed lands on the estuaries and river inlets are under hands of agricultural companies and all the spatial structures are formed by their intensions, objectives and perspectives. They constructed a Unit Farming Area for the sake of companies. Spatial structures are planned in a regular one with broad arable land for the rice production of rectangular blocks, regular canal systems and tank reservoir for the irrigation water supply into reclaimed lands. There developed a 'Central-located linear type' of settlements in midst of reclaimed land. These settlements are settled in a detail program upon this newly reclaimed land at once with a master plan and they have planned patterns in their distribution, building materials, location, and form. Ecological linkage between Newly settled settlemrnts and its surroundings are lost its colours and became a more artificial one by human-centred environment. [I-IT] landscapes are become more prominant. This region is a destination area of [Origin-Destination] theory model and formed a 'Pioneer Fringe'. It is a kind of pioneer front that could advance or retreat discontinously by physical conditions and socio-cultural conditions of that region.