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투기적 병렬 그래프 감축을 위한 대치과정이 지연된 람다 연산식
이용학(Yong-Hack Lee),전서현(Suh-Hyun Cheon) 한국정보과학회 1999 정보과학회논문지 : 시스템 및 이론 Vol.26 No.1
병렬 그래프 감축 모델에 있어서, 투기적 연산(speculative evaluation) 모델은 병렬성을 증가 시키지만 불필요한 연산으로 인해 자원을 낭비할 수 있다. 투기적 태스크가 람다 연산식을 WHNF(Weak Head Normal Form)로 감축할 때, 대치과정은 그래프를 증가시킬 수 있고, 많은 복사과정을 요구할 수 있다. 이러한 투기적 태스크는 나중에 불필요한 연산이 될 수 있고, 이 경우 이러한 투기적 태스크에서 발생한 다른 모든 투기적 태스크들을 종료해야 하는 부담이 있다. 또한 불필요하게 된 복사과정으로 인한 기억 공간을 재사용이 가능한 상태로 만들어 주어야 한다. 본 논문은 WHNF 또는 HNF로 감축할 때 발생할 수 있는 불필요한 대치과정으로 인한 오버헤드를 줄이기 위해 대치과정이 지연된 람다 연산식 형태(DSF : Deferred Substitution Form)를 제안한다. 이 형태는 대치과정을 필수적 태스크(mandatory task)가 수행할 때까지 지연시키기 위한 람다 연산식 형태이다. 대치과정이 지연된 람다 연산식 형태로의 감축을 수행하는 투기적 태스크에서, 대치과정이 존재하지 않기 때문에 그래프의 크기가 증가하지 않고 또한 복사과정을 요구하지 않는다. 따라서 연산식에 대한 대치과정이 지연된 람다 연산식 형태로의 감축이 불필요하게 된 경우 부담이 줄어들게 된다. 아울러 병렬성을 증가시키기 위한 연산 모델을 제안한다. In a parallel graph reduction system, speculative evaluation can increase parallelism but waste the machine resources by evaluating expressions which may eventually be discarded. When a speculative task reduces a lambda expression to WHNF (Weak Head Normal Form), substitution can lead to unbounded growth of the graph size and requires many copy operations. This speculative task may be unnecessary. In that case the performance is affected by the overheads to terminate all tasks to be propagated from the speculative task and to refresh the memory cells to be allocated for copy operation. We propose a lambda form called DSF(Deferred Substitution Form) in which substitution is deferred until a mandatory task will evaluate substitution. In the speculative task to DSF, since there is no substitution, it does not grow the graph and require copy operation. Therefore the overhead can be decreased when the expression reduced to DSF is eventually unnecessary. In addition, we propose an evaluation model for DSF to increase the parallelism.
오도석 ( Doe Suk Oh ),이용학 ( Yong Hack Lee ) 한국산업위생학회 2004 한국산업보건학회지 Vol.14 No.3
The aims of this study are to confirm the improvement by comparison with the excess-rate for exposure level of the harmful factors for working environmental measurement results of 1995~2003 year of automobile factories and to suggest direction for working environmental measurement in future. 1st, the harmful factor continuously issued at A(B; same factory) and C factories during 1995~2003 year was the noise. The total excess-rate of harmful factors for overall processes was 19.4% during 1995~1997 year, 2000~2001 year 9.4% in A(B) factory and C factory was 1.96% during 2001~2003 year. The results of improvement for harmful factors are as follows. 1. Noise; The total excess-rate for overall processes of A(B) factory was av. 24.9% during 1995~1997 and av. 19.7% during 2000~2001 and especially at 2001(13.6%) was very improved. The mainly improved process was the press-process. The excess-rate of C factory during 2001~2003 year was av. 6.1% for overall processes. 2. Manual material handling(MMH) and repeated works; The RWL excess-rate for MMH of A(B) factory was very high during 1995~1997 but during 1999~2001(61.5% → 7.1%)was very improved. The ANSI excess-rate for repeated works during 1995~1997 was 77.2%. The MMH for C factory have been automated and not issued. 3. Dusts(welding fume, Fe2O3 dust, and etc.) and heavy metals; During 1995~2003 the excess-rate for dusts and heavy metals was zero in A(B) and C factories. 4. Organic solvents; During 1995~1997 the excess-rate for organic solvents of A factory was 5.3% and during 1999~2001(zero%) was very improved. During 1995~2001 benzenes(A2) have been detected but not exceed exposure level. The excess-rate for C factory was zero% and benzenes were not detected. 5. The others(specific chemical materials, toxic gases, oil mists, asbestos, electromagnetic wave, vibration, heat, etc.) not exceed the exposure levels except the oil mist and the a few physical factors. 2nd, Until now as the chemical factors have been very improved, the direction of working environmental measurement in future will manage the chemical factors as the basis and enforce the physical factors(noise, vibration, electromagnetic wave etc. and the ergonomic factors(MMH and repeated work related with the CTDs).
용융 Sb-Pb-Ag 3원계 및 Sb-Pb-Bi-Ag 4 원계의 열역학적 성질에 관한 연구
이용학,문남일 대한금속재료학회(대한금속학회) 1992 대한금속·재료학회지 Vol.30 No.4
This study was undertaken to investigate the distribution ratio of silver between metals and slags during lead slime smelting processes. The antimony activities of the lipuid Sb-Pb-Ag system at 1250K were determined by using isothermal and isopiestic equilibrium methods. At 1250K, the equilibrium distributions between the Sb₂O₃ PbO slag and Sb-Pb-Ag metal, and Sb-Pb-Bi-Ag metal were studied. The results are summarized as follows;l) The activities of Sb in liquid Sb-Pb-Ag system at 1250K showed a slight negative deviation from Raoult's law at low Sb concentrations and obeyed Raoult's law at high Sb concentrations. 2) Liquid Sb-Pb-Ag system presents the behaviors of regular solution in a minute error. 3) Difference between the behaviors of silver and other elements during lead slime smelting processes was also discussed based on the thermodynamic data obtained in present investigations.
이용학,전일현 대한금속재료학회(대한금속학회) 1989 대한금속·재료학회지 Vol.27 No.10
The antimony activities in liquid Sb-Sn-Cu at 1423 K were determined by using isothermal-isopiestic method. On the other hand, based on the antimony activities in the Sb-Sn-Cu system which has been determined from the present work, the tin and copper activities were calculacted by use of the method proposed by Schuhmonn. The results are summarized as follows 1) The antimony activity exhibits negative deviation from Roultian behavior. 2) Liquid Sb-Sn-Cu system present regular solution behavior in an minute error. 3) The activity coefficients of tin and copper at infinite dilution in molten antimony at 1423 K are as follows lnγ_(sn)(X_(sn), X_(cu)) = ln 0.57 + 1.0X_(sn) + 1.25X_(cu), lnγ_cu(X_(cu) X_(sn)) = ln 0.41 + 1.2X_(cu) + 1.25X_(sn)