Earticle

에티오피아 정부는 농민들의 농업 생산성을 증대하기 위해 여러 가지 농업지원정 책들(agricultural package programs)을 도입해 왔다. 본 논문의 목적은 농업 생산성의 상태와 결정 요인을 고찰한 후 에티오피아 티그레이(Tigray) 지역의 패널 자료(panel data)를 사용하여 ‘통합된’ 농업지원정책들이 농업 생산성에 미치는 효과를 실증적으 로 추정하는데 있다. 이를 위해 두 가지 추정방법을 사용하였다. 첫째, 티그레이 지역에서 농업지원정책들이 농업 생산성에 미치는 효과를 실증적으로 분석하기 위해 고정효과(fixed effect) 추정방법을 사용하였다. 둘째, 농업지원정책에 참가하는 농민들의 평균적인 수혜효과를 추정하기 위해 Propensity Score Matching(PSM) 추정방법을 사용하였다. 이러한 추정방법을 사용하여 추정한 결과 다음 두 가지 시사점을 도출하였다. 첫째, 에티오피아 정부가 제공하는 농업지원정책들은 티그레이 지역의 농업 생산성 에 양(+)의 효과를 미치고 있으며, 이는 통계적으로도 유의하다. 이러한 추정 결과는 농업지원정책들에 ‘참가한’ 농민들의 생산성이 참여하지 않은 농민들보다 더 크다는 것을 의미한다. 둘째, PSM 추정 결과 농업지원정책들의 수혜효과가 참여 농민들에게 양(+)의 효과를 미치는 것으로 나타났다. 따라서 본 논문의 추정 결과는 에티오피아 의 농업 생산성 증대에 유용한 지침으로 사용될 수 있을 것으로 기대된다.

Ethiopian government has introduced various agricultural package programs in promoting agricultural productivity of the smallholder farmers. The paper attempts to explore the status and determinants of agricultural productivity, and estimate the impact of integrated agricultural package programs on farm productivity by using extensive panel data in the Eastern zone of Tigray in Ethiopia. Thus far, there have been no researches attempted to analyze the impact of the integrated agricultural package programs introduced to the farmers on various outcome variables in Tigray region in Ethiopia by using panel data. In doing so, we used two estimation methods: (i) the fixed effect (FE) estimation model to empirically evaluate the impact of household-based agricultural package programs on farm productivity in Tigray region, and (ii) the propensity score matching (PSM) method to estimate the average treatment effect on the treated (ATT). Our econometric estimates show the following two practical results. Firstly, household-based agricultural package programs have a positive and statistically significant impact on farm productivity in the Eastern zone of Tigray, Ethiopia. This implies that the agricultural household package participant households have higher productivity than the non-beneficiaries. Secondly, the propensity score matching (PSM) estimation result ensures that the ATT is positive and statistically significant for the package participant smallholder farmers. In the end, these outcomes provide governments with some useful guides to promote farm productivity in Tigray, Ethiopia.

연탄재의 순환자원화를 위하여 미연탄소와 광물질의 선별이 필요하다. 일반적으로 석탄은 천연적인 소수성 물질로 자연부유도가 높다. 그러나 심하게 산화를 받은 경우에는 그의 소수성이 약화된다. 따라서 연탄재에 존재하는 미연탄소는 연소과정에서 심하게 산화를 받았기 때문에 부유선별 시 어려움이 예상된다. 이에 고정탄소의 산화가 유상포수제 첨가량에 미치는 영향을 파악하고자 연탄의 출발물질인 무연탄과 연탄재를 비교하여 부선실험을 실시하였다. 무연탄 부선에서는 유상포수제의 첨가 없이도 고정탄소 기준으로 실수율이 약 70%이었다. 그리고 유상포수제의 첨가량이 증가할수록 실수율도 증가하여 500 g/ton 일 때, 실수율이 90%이였다. 한편 연탄재 부선에서는 유상포수제의 첨가 없이는 전혀 부유되지 않았으며 유상포수제의 농도가 증가할수록 미연탄소의 실수율은 증가하여 유상포수제의 농도가 1,500 g/ton일 때, 실수율은 80%이였다. 그러므로 연탄재 부선에서 산화된 미연탄소분의 실수율을 얻기 위해서는 무연탄 부선에 필요한 유상포수제의 첨가량 보다 3배 이상이 필요함을 확인하였다.

Separation of unburned carbon is needed from coal briquette ash (CBA) in order for recycling. In general, natural flotability of coal is high because of its pristine hydrophobic surface. However, hydrophobicity of the coal decreased when it was heavily oxidized. Since unburned carbon in the CBA was heavily oxidized during combustion process, its flotation was expected to be difficult. Flotation for anthracite (raw material of coal briquette) and the CBA was carried out to find out the effect of oxidation of fixed carbon on the dosage of oily collector. In case of the anthracite flotation. its recovery was about 70 wt% without an oily collector. Also, the increase of oily collector increased its recovery up to 90 wt% with 500 g/ton of collector consumption. On flotation of the CBA float product was not obtained without an oily collector. As the dosage of oily collector increased its recovery to 80 wt% with 1,500 g/ton of collector consumption. Therefore, it was confirmed that the flotation of the CBA required three times more oily collector than that of the anthracite in order to obtain the similar flotation result from the CBA and the anthracite.

본 연구는 포유중인 모돈에서 이유 전과 후에 성선자극호르몬 투여 및 예정시각 인공수정이 번식성적에 미치는 영향을 조사하였다. 포유중인 모돈은 대조구, 이유 전 2일 및 이유 후 1일에 성선자극호르몬을 주사 하였다. 성선자극호르몬을 주사한 모돈의 1/2은 발정확인 후 24 및 36시간에 인공수정 하였고, 1/2은 GnRH 주사 후 24 및 36시간에 각각 예정시각 인공수정 하였다.포유중인 모돈에서 대조구, 이유 전 및 이유 후 성선자극호르몬을 투여 하여 발정재귀를 관찰한 결과 이유 후 성선자극호르몬 투여구가 발정재귀율이 높게 조사 되였으나 유의적 차이는 없는 것으로 조사되었다. 성선자극호르몬 투여가 발정재귀 시간에 미치는 영향을 조사한 결과 이유 전 성선자극호르몬 투여구가 발정 재귀시간이 유의적으로 짧은 것으로 조사되었다(P<0.01). 포유중인 모돈에서 성선자극호르몬을 이유 전 또는 이유 후에 투여한 후 인공수정을 실시한 결과 분만율과 산자수는 유의적인 차이는 없었다. 예정시각 인공수정에 따른 산자수는 이유 전 성선자극호르몬 처리구와 이유 후 성선자극호르몬 처리구에서 예정시각 인공수정 처리구가 발정관찰인공수정에 비하여 유의적으로 적었다(P<0.01).이상의 결과를 종합해 보면 성선자극호르몬은 포유중인 모돈에서 난포를 발육시킬 수 있으며, 이유 전 성선자극호르몬의 투여는 발정재귀일의 단축 효과를 기대 할 수 있으나 포유돈에 있어 발정재귀율 개선과 향상된 번식성적과의 상관 관계 정립을 위한 추가적인 연구가 필요할 것으로 사료된다.

This study was to investigate the effectiveness of pre-weaning injection of gonadotropin and scheduled fixed-time insemination on sow fertility. Sows were randomly assigned to receive gonadotropin 2 days before weaning, 1 day after weaning or none as control. In gonadotropin treated groups, half of sows were inseminated twice at 24 and 36 hours after onset estrus and half of sows were inseminated twice at scheduled fixed-time. Weaning to onset of estrus was the shortest in lactating sows injected with gonadotropin prior to weaning. Liter size was significantly higher in AI groups after detection of estrus, compared to fixed-time AI group. Results of these experiments indicated that injection of gonadotropin in lactating sows could initiate the final follicular development, and has potential to enhance the reintegration of estrus. Further researches are needed to define the relationship between reduced interval of wean to onset estrus and enhanced fertility in lactating sows.

The purpose of this study is to find out the effects of brick paved under-surface soil physical properties which are changed by fixed trampling. Thus, a sandy loam which is known as a profitable soil for plants is used an experimental soil to study the changes of the soil physical properties. It is related to sand bed's thickness & particle size which are settled by experimental variable factors. According to the variation of sand bed's particle size, bulk density and soil hardness at natural dryed soilcondition result in 0.075~2.00mm>2.00~5.00mm>2.00~8.00mm>5.00~8.00mm, and water content at natural dryed soil condition are observed being insensible change rate from the point that sand thickness is 30~40mm and more sand bed's thickness constructed by the variation of sand bed's thickness.

The Educational Restitution Rate is an important parameter that determines the quality of university education. This paper analyzed data from 148 private universities over the 10 years from 2009 to 2018 using data mining techniques in Korea. A significant causal relationship is detected in the fixed effect model as a result of the panel estimation. And the scale of faculty expansion and fund management, which are the university evaluation indicators, and the size of basic funds, respectively, have a positive effect on the ERR, which is within the confidence interval. In the analysis, the more private universities improve the tuition dependence rate, the more decisively positive affecting ERR. As a result of nonparametric regression estimation, when the faculty expansion ratio is reinforced, the effect of economies of scale is detected in some sections, the improvement of the tuition dependence rate, and the result value is generated through the improvement that results are derived at a certain point in time. We hope that the university based on this study can be a basic Indicators for the diagnosis of basic competencies and policy of student-centered education.

The purpose of this study is to investigate whether recent investment in the Korean energy sector has affected the increase in the share of renewable energy and to find this result has an effect on the decrease of carbon emission sequentially. We used panel model and OLS to grasp these relations. The data used in this study are from Foreign investment in Korea power sector for 12 years by the Export-Import Bank of Korea (2004 ~ 2016) as a time-series data, and a panel comprising 17 wide-area regions across the country as a cross-section. The result of this study shows that the foreign investment increased the production of new renewable energy and reduces carbon emissions.

본 연구는 기업의 사회공헌이 재무적 성과로 이어지는지 혹은 재무적 성과가 사회공헌으로 이어지는지에 관해 연구한 것이다.

A Study of the Relationship between Corporate Social Performance and Financial Performance-Analysis by Fixed Effect Regression Method

The Korean economy has achieved the high rates of economic growth during the last four decades through the export-led growth strategy by the government. It is well recognized that the export in the Korean manufacturing industries has been still leading the Korean economic growth. The purpose of this paper is to investigate the importance of industry-specific variables in determining the export performance of manufacturing industries in Korea during the period 1975:1-2010:4 using data pooling analysis. Our main findings are summarized as follows. The effect of markup on export growth is highly significant with positive sign. The rapid declines in interest rates and import prices since the foreign crisis occurred should have resulted in the cost advantages in exporting industries, which in turn could have substantially contributed to export growth. Thus, it may be concluded that the ratio of capital to labor and the ratio of foreign intermediate goods to industrial output are significantly industry-specific determinants in explaining the export performance.

The fixed effects panel probit model faces "incidental parameters problem" because it has a property that the number of parameters to be estimated will increase with sample size. The maximum likelihood estimation fails to give a consistent estimator of slope parameter. Unlike the panel regression model, it is not feasible to find an orthogonal reparameterization of fixed effects to get a consistent estimator. In this note, a hierarchical Bayesian model is proposed. The model is essentially equivalent to the frequentist's random effects model, but the individual specific effects are estimable with the help of Gibbs sampling. The Bayesian estimator is shown to reduce reduced the small sample bias. The maximum likelihood estimator in the random effects model is also efficient, which contradicts Green (2004)'s conclusion.

This paper examines the relative magnitude of trade-creating and trade-diverting effects of some important RTAs using a panel dataset consisting of observations for every five years beginning in 1950 and ending in 1999, taken from Andrew Rose’s gravity model (2004) database. The result of the Hausman test shows that the random effect estimators (RE) are inconsistent on account of the endogeneity bias. Therefore, fixed effect estimators (FE) are more suitable than random effect estimators. To avoid unobservable omitted variables, various estimation experiments were used from country-pair fixed effect, country-pair fixed effect combined with time dummy, and time-varying country dummies. Several features deserve attention. First, the trade-creating effects in five of the ten RTAs (EC, CACM, MERCOSUR, ASEAN, and SPARTECA) are rather striking. Second, it is interesting to see the trade-creating effects decreasing more in some RTAs (EC, CACM, MERCOSUR, ASEAN) if we use more rigorous experiments, that is, in terms of absorbing the effects of multilateral resistance. This could suggest that the trade-creating effects are over-estimated without controlling the country heterogeneity bias. Finally, the EU and NAFTA seem to be relatively less open trade blocs than are MERCOSUR and ASEAN.

We examine the effects of the Basic Elder Pension (BEP) in Korea on self-assessed health for the elderly of age 65 or higher, using two wave Korean panel data. As there could be innately healthy/optimistic individuals, it is important to allow for time-constant individual effects possibly related to regressors,which is, however, difficult as the dependent variable takes on four ordered categories. To overcome this difficulty, we transform the ordered discrete response into binary, and apply Panel Conditional Logit Estimator (PCLE) to the binary model. Since there are three ways to transform four ordered categories into binary,we obtain three PCLE’s in total. To impose the restriction that the same parameters are estimated in those PCLE’s, we use minimum distance estimator. We find that BEP has a small positive effect that is significant: 100% increment in BEP would result in an increment of 3?7% of ‘one standard deviation of the latent continuous health propensity’. Finding a small effect might be natural, as improving health for the elderly would be a hard thing to do.

배경 및 목적: 격자 레이아웃 기반의 AAC 디스플레이가 임상현장에서 높은 활용을 보임에도 불구하고 그림상징의 고정된 배열이 주는 효과에 대해서는 보고된 바가 거의 않다. 본 연구는 복합적인 의사소통 장애를 가진 사람들에게 근거 기반의 AAC 중재를 제공하고자 문장구성 과제를 통하여 상징의 고정배열이 주는 효과를 살펴보았다. 방법: 20대와 30대로 구성된 32명의 정상성인이 연구에 참여하였고 이들에게 고정배열 조건과 비고정배열 조건에서 주어진 문장에 해당되는 그림상징들을 선택하도록 하였다. 실험에 사용된 25 개의 자극어는 명사-부사-동사로 이루어진 문장으로 구성하였으며 두 조건에 동일하게 사용되었다. 피험자들의 과제수행은 정반응수와 반응시간을 중심으로 비모수통계방법을 사용하여 분석하였다. 결과: 두 배열 조건 모두에서 높은 정반응이 보였으나 반응시간에있어서는 유의한 차이를 보였다. 고정배열 조건에서 유의하게 더 빠른 반응을 보였으며 이는 그림상징의 선택 순서와 상관없이 일관되게 비고정배열 조건보다 더 빠른 것으로 나타났다. 노출되는 횟수가 증가할수록 두 배열 조건에서 피험자들의 반응이 유의하게 빨라졌으나 상관관계는 비고정보다 고정배열 조건에서 더 큰 것으로 나타났다. 논의 및 결론: 본 연구의 결과는 AAC 시스템에서 일련의 상징들을 선택 및 결합하여 문장을 구성할 때에 고정된 상징 배열이 긍정적인 영향을 끼친다는 경험적 자료를 제공한다. 아울러 고정배열이상징의 위치를 회상해내는 데에 필요한 인지적 부담을 감소시켜 전반적인 의사소통 속도를 증진시킨다는 것을 보여준다.

Objectives: Despite the dominant use of grid-based augmentative and alternative communication (AAC) displays, the effect of fixed array of graphic symbols has not been thoroughly studied, which makes it challenging for clinicians to provide evidence-based AAC intervention to individuals with complex communication needs. The current study aimed to determine the effect of fixed array symbols on sentence composition. Methods: Thirty-two healthy adults between 20 to 30 years old participated in the study. They were asked to locate three symbols in a fixed array condition and a non-fixed array condition for 25 identical noun-adverb-verb target sentences. The difference in accuracy and response time was analyzed by using a non-parametric two-related samples test and a Spearman correlation test. Results: Although there was no difference in the number of correct responses, participants showed significantly faster responses in the fixed array condition than in the non-fixed condition. Regardless of the selection order, participants located symbols faster in the fixed array condition. As the number of exposures to the located symbols increased, the total selection time in the fixed array condition decreased moderately. Conclusion: The findings support the idea that a fixed array condition may facilitate locating a sequence of graphic symbols in an AAC system by reducing cognitive load in recalling the location of target symbols.

Objectives: Aging is an unconscious and gradual process that can lead to changes in biological systems. Induction of oxidative stress and apoptosis, hepatotoxicity and neurotoxicity are involved in the aging process. Regarding the antioxidant property of black seed oil, the aim of this study was to evaluate the anti-aging effect of Nigella sativa (N. sativa) oil on d-galactose-induced aging in mice. Methods: For induction of aging, D-galactose (500 mg/kg, subcoutaneously SC) was administrated to male mice for 42 days. Animals were treated with D-galactose alone or with b lack seed oil (0.1, 0.2, 0.5 mL/kg, intraperitoneally (ip)). Additionally, vitamin E (200 mg/kg) was used as a positive control. At the end of treatment, the malondialdehyde (MDA) and the glutathione (GSH) contents in brain and liver tissues were measured. Also, enzymes in serum, including aspartate aminotransferase (AST) and alanine amino transferase (ALT), were determined. The levels of the proteins Bax, Bcl2, caspase-3 (pro and cleaved) in brain and liver tissues were evaluated. Results: Administration of D-galactose (500 mg/kg, SC) for 42 days increased serum levels of ALT and AST, as well as the MDA content, in brain and liver tissues, but decreased the GSH content. Additionally, the levels of apoptotic proteins, including Bax, procaspase-3 and caspase-3 cleaved, were markedly increased. N. sativa oil (0.1 and 0.2 mL/kg) diminished the levels of the biochemical markers ALT and AST. Administration of black seed oil (0.1, 0.2 and 0.5 mL/kg) reduced lipid peroxidation and at doses 0.1 and 0.2 mL/kg significantly recovered the GSH content. The oil decreased Bax/Bcl2 levels and at 0.1 mL/kg down-regulated the expressions of caspase-3 (pro and cleaved) proteins in brain and liver tissues. Conclusion: Through its antioxidant and anti-apoptosis properties, black seed oil exhibited an anti-aging effect in a model of aging induced with D-galactose.

PURPOSE. To evaluate and compare the effect of impression type (conventional vs digital) and the number of implants on the time from the impressions to the generation of working casts of mandibular implant-supported fixed completearch frameworks, as well as on patient satisfaction. MATERIALS AND METHODS. 17 participants, 3 or 4 implants, received 2 types of digital impression methods (DI) and conventional (CI). In DI, two techniques were performed: scanning with the scan bodies (SC) and scanning with a device attached to the scan bodies (SD) (BR 10 2019 026265 6). In CI, the making of a solid index (SI) and open-tray impression (OT) were used. The outcomes were used to evaluate the time and the participant satisfaction with conventional and digital impressions. The time was evaluated through the timing of the time obtained in the workflow in the conventional and digital impression. The effect of the number of implants on time was also assessed. Satisfaction was assessed through a questionnaire based on seven. The Wilcoxon test used to identify the statistical difference between the groups in terms of time. The Mann-Whitney test was used to analyze the relationship between the time and the number of implants. Fisher's test was used to assess the patient satisfaction (P<.05). RESULTS. The time with DI was shorter than with CI (DI, $\tilde{x}=02:58$; CI, $\tilde{x}=31:48$) (P<.0001). The arches rehabilitated with 3 implants required shorter digital impression time (3: $\tilde{x}=05:36$; 4: $\tilde{x}=09:16$) (P<.0001). Regarding satisfaction, the DI was more comfortable and pain-free than the CI (P<.005). CONCLUSION. Digital impressions required shorter chair time and had higher patient acceptance than conventional impressions.

Statement of problem. Translucency and masking effect of provisional crown and fixed partial denture materials is an important esthetic consideration. But, provisional resin materials differ substantially in their ability to mask underlying colors. Purpose. The purpose of this study was to evaluate the translucency differences of provisional resin materials at various thicknesses and the correlation between the translucency and the masking efficiency. Material and methods. Two polymethyl methacrylate resins (Jet Tooth Shade, Alike) and three resin composites (Protemp 3 Garant, Luxatemp and Revotek LC) were used. Specimens (n=6) were fabricated from each material in 0.3, 0.5, 0.8, 1.0, 1.5, 2.0 and 3.0 mm thickness. The CIELAB parameters of each specimens were measured using a spectrophotometer. The translucency parameter (TP) values and the masking effect $({\Delta}ME^*{_{ab}})$ values were computed and all data were statistically analyzed by one-way ANOVA and the multiple comparisons Scheffe test. The correlation between the thickness and the TP values and the correlation between the thickness and the ${\Delta}ME^*{_{ab}}$ values were also evaluated by correlation analysis and regression analysis. Results. The TP values and the ${\Delta}ME^*{_{ab}}$ values were significantly related to the thickness in all specimens. The TP values were more sensitive to the change of thickness than the ${\Delta}ME^*{_{ab}}$ values. The order of the translucency by brand was different from the order of the masking effect by brand in all thickness groups. Conclusion. Within the limitations of this study, the translucency and masking effect of the provisional resin materials investigated were significantly related to their thickness. The masking effect of provisional resin was correlated with the translucency parameter, but the order of the masking effect by brand was different from the order of the translucency parameter.

PURPOSE. This study assessed the physical and mechanical properties of interim crown materials fabricated using various digital techniques after accelerated aging. MATERIALS AND METHODS. Three groups of interim dental restorative materials (N = 20) were tested. The first group (CO) was fabricated using a conventional manual method. The second group (ML) was prepared from prefabricated resin blocks for the milling method and cut into specimen sizes using a cutting disc. The third group (3D) was additively manufactured using a digital light-processing (DLP) 3D printer. Aging acceleration treatments using toothbrushing and thermocycling simulators were applied to half of the specimens corresponding to three years of usage in the oral environment (N = 10). Surface roughness (Ra), Vickers microhardness, 3-point bending, sorption, and solubility tests were performed. A 2-way analysis of variance (ANOVA) and Fisher's multiple comparison test were used to compare the results among the groups. RESULTS. The mean surface roughness (Ra) of the resin after accelerated aging was significantly higher in the CO and ML groups than that before aging, but not in the 3D group. All groups showed reduced hardness after accelerated aging. The flexural strength values were highest in the 3D group, followed by the ML and CO groups after accelerated aging. Accelerated aging significantly reduced water sorption in the ML group. CONCLUSION. According to the tested material and 3D printer type, both 3D-printed and milled interim restoration resins showed higher flexural strength and modulus, and lower surface roughness than those prepared by the conventional method after accelerated aging.

Purpose: This pre-clinical study aimed to compare the efficacy of L-shaped, loosely packed soft block bone substitutes (BBS, LP group) with that of non-trimmed, compactly packed soft BBS (CP group), both covered with a non-fixed collagen membrane, on augmentation stability and new bone formation in chronic peri-implant dehiscence defects treated with guided bone regeneration (GBR). Methods: In 4 mongrel dogs, 4 standardized box-shaped buccal defects were surgically created in each jaw. Following a 4-week period of spontaneous healing, a total of 32 dental implants were placed, with 2 implants inserted into each defect. Each defect was randomly assigned to either the LP or CP group. Statistical comparisons between groups were conducted using the Mann-Whitney U test. Bland-Altman and Spearman correlation analyses were also performed to evaluate the relationship and agreement between micro-computed tomography (micro-CT) and histomorphometric measurements. Results: Micro-CT and histomorphometric analyses revealed no significant differences in bone width at any apical level between the LP and CP groups. Both groups exhibited similar increases in bone width, although bone retention in the coronal region remained limited. Additionally, micro-CT tended to slightly overestimate bone width (mean difference, 0.31 mm), but showed a strong correlation with histomorphometric analysis (r=0.971, P<0.001), supporting the reliability of radiographic methods for bone assessment. Conclusions: Neither LP nor CP soft BBS effectively prevented morphological collapse in the coronal region of augmented sites when used without additional membrane fixation. These findings underscore the necessity of enhanced stabilization techniques to improve structural integrity and bone regeneration in GBR procedures.

STATEMENT OF PROBLEM: Implant-supported fixed cantilever prostheses are influenced by various biomechanical factors. The information that shows the effect of implant number and position of cantilever on stress in the supporting bone is limited. PURPOSE: The purpose of this study was to investigate the effect of implant number variation and the effect of 2 different cantilever types on stress distribution in the supporting bone, using 3-dimensional finite element analysis. MATERIAL AND METHODS: A 3-D FE model of a mandibular section of bone with a missing second premolar, first molar, and second molar was developed. $4.1{\times}10$ mm screw-type dental implant was selected. 4.0 mm height solid abutments were fixed over all implant fixtures. Type III gold alloy was selected for implant-supported fixed prostheses. For mesial cantilever test, model 1-1 which has three $4.1{\times}10$ mm implants and fixed prosthesis with no pontic, model 1-2 which has two $4.1{\times}10$ mm implants and fixed prosthesis with a central pontic and model 1-3 which has two $4.1{\times}10$ mm implants and fixed prosthesis with mesial cantilever were simulated. And then, 155N oblique force was applied to the buccal cusp of second premolar. For distal cantilever test, model 2-1 which has three $4.1{\times}10$ mm implants and fixed prosthesis with no pontic, model 2-2 which has two $4.1{\times}10$ mm implants and fixed prosthesis with a central pontic and model 2-3 which has two $4.1{\times}10$ mm implants and fixed prosthesis with distal cantilever were simulated. And then, 206N oblique force was applied to the buccal cusp of second premolar. The implant and superstructure were simulated in finite element software(Pro/Engineer wildfire 2.0). The stress values were observed with the maximum von Mises stresses. RESULTS: Among the models without a cantilever, model 1-1 and 2-1 which had three implants, showed lower stress than model 1-2 and 2-2 which had two implants. Although model 2-1 was applied with 206N, it showed lower stress than model 1-2 which was applied with 155N. In models that implant positions of models were same, the amount of applied occlusal load largely influenced the maximum von Mises stress. Model 1-1, 1-2 and 1-3, which were loaded with 155N, showed less stress than corresponding model 2-1, 2-2 and 2- 3 which were loaded with 206N. For the same number of implants, the existence of a cantilever induced the obvious increase of maximum stress. Model 1-3 and 2-3 which had a cantilever, showed much higher stress than the others which had no cantilever. In all models, the von Mises stresses were concentrated at the cortical bone around the cervical region of the implants. Meanwhile, in model 1-1, 1-2 and 1-3, which were loaded on second premolar position, the first premolar participated in stress distribution. First premolars of model 2-1, 2-2 and 2-3 did not participate in stress distribution. CONCLUSION: 1. The more implants supported, the less stress was induced, regardless of applied occlusal loads. 2. The maximum von Mises stress in the bone of the implant-supported three unit fixed dental prosthesis with a mesial cantilever was 1.38 times that with a central pontic. The maximum von Mises stress in the bone of the implant-supported three-unit fixed dental prosthesis with a distal cantilever was 1.59 times that with a central pontic. 3. A distal cantilever induced larger stress in the bone than a mesial cantilever. 4. A adjacent tooth which contacts implant-supported fixed prosthesis participated in the stress distribution.