• 대한치과보철학회지
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• 제34권3호
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• pp.539-573
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• 1996

This investigation was designed to determine the effectiveness of the posterior occlusal schemes on masticatory activity during mastication in complete denture. Twelve edentulous subjects were selected for this study. All subjects had no past history and no functional abnormality on masticatory system and TMjoint. And, they had residual ridge of favorable morphology, firm mucosa and Class I skeletal jaw relationship, Twelve experimental denture with interchangeable occlusions(0-degree teeth, 30-degree teeth, Levin teeth and S-A teeth) were constructed for this study. The masticatory performance was analyzed by means of standard sieve(10, 16, 20, 30sieve), and the electrical activity from selected muscles(Temporalis and Masseter muscle) was recorded simultaneously with electromyography(Bio-Pak system) as the subject masticated test foods (rice, peanut and gum) with four different occlusal schemes. Mandibular movement was, also, measured with Sirognathography(Bio-Pak system). These recordings were performed in immediately, after 1 week and after 2 weeks of insertion of complete denture. The results were as follows; 1. The average masticatory performance of 0-degree artificial teeth was higher than any other artificial teeth. 2. Masticatory performance in denture wearer was affected preferentially by food and artificial occlusal schemes. 3. During chewing, there was a statistical difference of EMG activity between masseter and temporal muscle(p<0.01). Especially, EMG activity of working masticatory muscle was highly affected by food rather than by artificial occlusal schemes. 4. In denture wearer, the velocity of opening was not affected by food, whereas, the velocity of closing was faster in soft food chewing than in hard food chewing, and the amount of vertical displacement was grater in chewing of soft and large bolus than in chewing of hard and small bolus. However, the amount of lateral displacement showed conversely (p<0.05). 5. It was considered that masticatory performance in denture wearer is not affected by the condition of residual ridge, the history of denture wear, the preference, the adaptation to artificial teeth and the total mesiodistal length of artificial posterior teeth.

• Journal of Korea Trade
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• 제25권7호
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• pp.1-18
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• 2021

Purpose - In this study, we explore the relationship between the degree of internationalization (DOI) and firm performance (DOI-P) of small and medium-sized enterprises (SMEs) in the manufacturing sector. Specifically, we investigate whether the costs and benefits dynamics concerning the internationalization of SMEs differ between high-tech and non-high-tech industries. Design/methodology - We extend the prior literature on this relationship by employing 5-year data on 589 Korean SMEs in the manufacturing sector and examining the moderating impact of the industry characteristics. Our findings reveal a U-shaped relationship between the DOI and SME performance. High-tech SMEs demonstrate an inverted U-shaped relationship, whereas non-hightech SMEs exhibit a U-shaped relationship. Findings - Our findings illustrate the importance of the industry factor in testing the performance impact of the internationalization of Korean SMEs. By incorporating industry dynamics, our results indicate that the DOI-P relationship depends on the context of the industry in which an SME operates. High-tech SMEs also display a higher DOI but are outperformed by non-high-tech SMEs for the entire internationalization path, which implies that high-tech SMEs face more challenges than non-high-tech SMEs while seeking internationalization. Originality/value - The findings strongly validate that significant benefits exist for SMEs undertaking internationalization. We also employ the contextual framework contributing to increasing the understanding of the intrinsic value of internationalization and resolving the mixed results issue on the DOI-P relationship, by illustrating that the industry factor leads to different dynamics of costs and benefits of SME internationalization; it also determines the shape and direction of the relationship.

• 한국공작기계학회논문집
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• 제14권2호
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• pp.69-74
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• 2005

Since the use of CFC and HCFC refrigerants is to be restricted due to the depletion of ozone layer, this experiment applies the $NH_{3}$ gas to study the performance characteristics from the superheat control for improving the energy efficiency. The experiments are carried out for the condensing pressure of refrigeration system from 1500kPa to 1600kPa by 50kPa and for degree of superheat from $0^{circ}$ to $1^{circ}$ by $10^{circ}$ at each condensing pressure. As a result of experiment, 1) As degree of superheat increased, evaporating pressure of the compressor decreased so equilibrium temperature decreased. And specific volume of refrigerant vapors increased so refrigerant mass flow and heat load of the evaporator decreased. 2) An influence of change of condensing pressure on heat load of the evaporator was insignificant. 3) With the identical degree of superheat, change of compressed temperature was insignificant according to each condensing pressure, so there was little change in enthalpy.4) when the degree of superheat is $0^{circ}$C at each condensing pressure, the refrigeration system has the hi띤est performance.

• 한국학교보건학회지
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• 제23권2호
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• pp.295-307
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• 2010

Purpose: This study was conducted to find ways to improve foodservice quality and satisfaction of middle school students in school lunch service. Recognition of concerns about school lunch and quality attributes was evaluated by gender. And we tried to investigate quality attributes which could affect degree of foodservice satisfaction by gender. Methods: Two hundred students from each of 6 middle schools (3 schools in urban and 3 schools in rural) in Gyeonggi Province were surveyed using self-developed questionnaires. Total of 1,103 questionnaires (male 556 and female 547) were collected and data were analyzed using descriptive analysis, t-test, cross table and stepwise multiple regression by SPSS 11.0. Results: There were not significant differences in average importance scores (male 4.09, female 4.06) and average performance scores (male 3.36, female 3.30) of quality attributes between middle school boys and girls. But there were significant differences in 7 and 6 of 25 quality attributes in evaluating importance and performance respectively by gender. There was not a significant difference (male 3.13, female 3.24) in degree of foodservice satisfaction by gender. But there were significant differences in the distribution of satisfaction. Stepwise multiple regression analysis showed that degree of satisfaction was influenced by a taste of food, quick complaint handling, providing favorite foods, and food hygiene in male students (F=$51.1^{***}$, adjusted $R^2$=.265). Degree of satisfaction was influenced by a taste of food, providing favorite food, proper meal prices, providing a wide variety of food in female students (F=$91.4^{***}$, adjusted $R^2$=.399). Conclusion: We found out that there were significant differences in quality attributes when evaluating importance and performance and in quality attributes which could affect foodservice satisfaction by gender.

• 한국산학기술학회논문지
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• 제10권10호
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• pp.2565-2571
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• 2009

본 논문은 시스템의 운전조건하에서 R717-R747용 이원냉동 사이클의 성능 분석에 대한 기초 설계자료를 제공하는 것이다. 본 논문에서 고려한 운전변수는 암모니아 고온사이클과 이산화탄소 저온사이클의 과냉각도, 과열도, 응축과 증발온도이다. 이원 냉동사이클의 성적계수는 과열도가 증가할수록 증가하는 반면, 과냉각도가 증가할수록 감소한다. 그리고, 이원 냉동사이클의 성적계수는 응축온도와 함께 증가하지만, 증발온도와는 반대로 감소한다. 따라서, 과열도, 과냉도, 응축과 증발온도는 본 시스템의 성적계수에 영향을 미치는 것을 알 수 있었고, 최대 성능계수와 최적의 증발온도에 대한 수학 방정식을 개발하기 위해 이러한 변수들을 포함시켜 다중 회귀분석을 통해 제안하였다.

• 설비공학논문집
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• 제17권4호
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• pp.297-302
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• 2005

Since the use of CFC and HCFC refrigerants are to be restricted due to the depletion of ozone layer, this experiment applies the $NH_3$ gas to study the performance characteristics of $NH_3$ refrigeration system by the superheat control for improving the energy efficiency. The experiments are carried out for the condensing pressure of refrigeration system from 1,500 kPa to 1,600 kPa and for degree of superheat from $0^{\circ}C\;to\;10^{\circ}C$ at each condensing pressure. As a result of experiment, when the degree of superheat is $0^{\circ}C$ at each condensing pressure, the refrigeration system has the highest performance.

• 한국도로학회논문집
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• 제15권5호
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• pp.217-226
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• 2013

PURPOSES : Under the capacity conditions with balanced approach flows, roundabouts give less delay than existing signalized intersections; however, flows over 450 vehicles/hour/lane with unbalanced approach flow conditions, roundabouts efficiency drops due to the short time difference between the critical gap and the follow-up headway. The purpose of this study is developing a roundabout Signal Metering operation method by considering approach lanes degree of saturation. METHODS : A four-way-approach with one-lane roundabout is selected to compare the Signal Metering performance for the case of 16 different unbalanced flow conditions. Based on these traffic conditions, the performance is evaluated for 64 different cases of Signal Metering combinations by using SIDRA software. A degree of saturation(V/C ratio) sum for two adjoined approaches is used for the performance index of choosing Metered Approach and Controlling Approach. RESULTS : When the V/C ratio sum is 0.29~0.81 and Metered Approach flow is less than Controlling Approach flow, the average delay saving per vehicle is about 7 seconds; however, after this rage the delay saving decreases gradually until the V/C ratio sum reaches around 1.0. The range of V/C ratio sum 0.93~1.09 provides average delay saving per vehicle about 3 seconds. In case of V/C ratio sum is grater than 1.0 and the flows of Metered Approach is grater than Controlling Approach, the average delay per vehicle increases 3~11 times respectively. CONCLUSIONS : As expected, the Signal Metering provides substantial improvements in delay saving for the case of V/C ratio sum is 0.3~1.0 under the traffic flow conditions of Metered Approach is less than Controlling Approach.

• 공학교육연구
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• 제27권1호
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• pp.3-12
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• 2024

The degree-linked programs for employees, operated by joint training centers in specialized universities that have implemented work-study integrated programs, are educational programs that require an annual government budget of around 80 billion KRW. However, the 70+ universities running these programs face issues such as a decline in academic achievement and an increase in dropout rates among students. In this paper, I conducted multiple regression analysis based on observed and measured information to examine whether the participating students in these programs are achieving an appropriate level of academic performance and to identify the factors that universities need to invest in to achieve that level. To do this, I hypothesized a causal relationship between the university's input factors and students' academic achievement, and used the SPSS program to analyze the statistical data, confirming the validity of the hypothesis. The collected data for the study were obtained through a survey developed using a Likert 4-point scale, which quantified the distribution of grades among students enrolled in IT-related departments offering the degree-linked programs for employees and the emotional contact efforts made by the universities to motivate them for academic success. Particularly, through the results of multiple regression analysis, it was confirmed that these input factors, unlike those for students in general education programs, require more personalized and frequent interactions.

• Animal Bioscience
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• 제37권8호
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• pp.1333-1344
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• 2024

Objective: Litter size and piglet loss at birth significantly impact piglet production and are closely associated with sow parity. Understanding how these traits vary across different parities is crucial for effective herd management. This study investigates the patterns of the number of born alive piglets (NBA), number of piglet losses (NPL), and the proportion of piglet losses (PPL) at birth in Landrace sows under tropical conditions. Additionally, it aims to identify the most suitable model for describing these patterns. Methods: A dataset comprising 2,322 consecutive reproductive records from 258 Landrace sows, spanning parities from 1 to 9, was analyzed. Modeling approaches including 2nd and 3rd degree polynomial models, the Wood gamma function, and a longitudinal model were applied at the individual level to predict NBA, NPL, and PPL. The choice of the best-fitting model was determined based on the lowest mean and standard deviation of the difference between predicted and actual values, Akaike information criterion (AIC), and Bayesian information criterion (BIC). Results: Sow parity significantly influenced NBA, NPL, and PPL (p<0.0001). NBA increased until the 4th parity and then declined. In contrast, NPL and PPL decreased until the 2nd parity and then steadily increased until the 8th parity. The 2nd and 3rd degree polynomials, and longitudinal models showed no significant differences in predicting NBA, NPL, and PPL (p>0.05). The 3rd degree polynomial model had the lowest prediction standard deviation and yielded the smallest AIC and BIC. Conclusion: The 3rd degree polynomial model offers the most suitable description of NBA, NPL, and PPL patterns. It holds promise for applications in genetic evaluations to enhance litter size and reduce piglet loss at birth in sows. These findings highlight the importance of accounting for sow parity effects in swine breeding programs, particularly in tropical conditions, to optimize piglet production and sow performance.

• 대한인간공학회지
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• 제30권2호
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• pp.291-296
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• 2011

This study was designed to investigate the effects of an ankle foot orthosis(AFO) with variable ankle joint angles on balance performance in healthy adults. Eighteen healthy adults were recruited in this repeated measures design with subjects as their own controls. An AFO with four kinds of ankle joint angles(-5, 0, 5, and 10 degree) were used and balance performance was measured during single limb standing. Three trials were obtained and then averaged for data analysis. Foot pressure was measured using an F-scan system and muscle activity was measured using an MP150 system. There were significant differences in balance performance with ankle joint angles. An AFO with -5 degrees was associated with significant increases in postural sway(anterior-posterior), and in muscle activity for the medial gastrocnemius and tibialis anterior compared with other degrees of angle. Findings of this study show that angles of an AFO are related to balance performance and a joint angle of 10 degree is effective for promoting joint stability and postural control. This information can be used by clinicians to prescribe AFOs.